More on the EGR Bypass Valve....Modify or Leave alone
 

Just been reading an article on Honest John an excellent review Website:
http://www.honestjohn.co.uk/carbycar/
See also
http://www.honestjohn.co.uk/carbycar/index.htm?md=121&

This is admittedly about a Ford Galaxy 1.9Tdi, but I wonder if this would apply to 75 ZT owners who have disabled their EGR or fitted a bypass.

The consequences can be dire...............read on

"On TDIs, EGR valve should open to allow carbon dioxide, which acts as a cooling gas) into the combustion chambers when the engine is under load (>30% boost). This allows the combustion chamber temperature to drop and thus the temperature of the exhaust gases. If it sticks in the closed position the exhaust gas temperature will rise causing a) the turbo bearings to fail and b) engine oil into the induction system. This can cause the engine to run on its crankcase oil until it is either stalled or goes bang. Problems with EGR valves in TDI engines are often the cause of rough running when the valve is stuck in the open position as well. In several cases turbos have blown but the EGR valve has not been replaced. Inevitably the new turbo unit will not last long."

Come on technical bods, lets have some more clarification on this subject!

Left:............................................. ..........Right
choked EGR 40k miles.................................EGR Bypass Tube
http://www.the75andztclub.co.uk/foru...e47005bdc3.jpg

oooer!:o Dunno, but after 10,000 miles I have found no problems...

lets hope my Mobil 1 every 7500 miles keeps dem bearings happy :D

The whole statement seems to have a lot of flaws:

1. How can exhaust gasses (that the Egr lets in to the manifold) be cooler than the intake air?

2."On TDIs, EGR valve should open to allow carbon dioxide, which acts as a cooling gas) into the combustion chambers when the engine is under load (>30% boost)."
The whole idea of the Egr is to recirculate some of the exhaust gasses that are more likely to have a higher concentration of unburned fuel.(If you've ever tried to open an egr, it takes a lot of vacumn!)
Eg. on the over-run or if you accelerate too harshly.(throttle opening more than engine can draw in)

3."This can cause the engine to run on its crankcase oil until it is either stalled or goes bang." Of course a engine runs on its crankcase oil what other oil would it use!!!!
Unless he means the oil from the failed turbo bearings entering the induction system and being burnt, but that wouldn't cause your engine to go bang.
If it was that bad then the engine wouldn't run as the ECU would find it difficult to cope.
The Police would have stopped you way before then, for the amount of smoke you would be pumping out of the exhaust. I've had major bearing falure on a turbo and believe me you'd know about it!

4. Exhaust gasses reaching a temperature that would lead to failure of the turbo bearings. What's he running his diesels on???


The only part of this statement I agree with is that, an egr that is stuck partially open will cause rough running of the engine.


Does this guy know what he's talking about? I doubt it.

Egr bypasses make the engine more efficiant by increasing the amount of air that is entering the engine. It won't cause any of the problems described above. If I thought it would have any detrimental effect I certainly wouldn't have fitted one!


Russ

I must admit other than give it a clean this is a mod that I haven't done on my car. I was hoping to see some dyno evidence that it was worth while first.

What I can say is if you open the egr valve via testbook with the engine running at slow speed it causes very noticeable rough running and does a pretty good impression of a duff maf performance wise, hence why I guess it is only designed to open at high speed where the performance impact is reduced and I believe it is its role to reduce emissions that it is there for rather than any other reason.

One of our members came over a couple of weeks ago and his egr gave all the symptoms of sticking open although testing it via Testbook suggests it was not as it would then close and open on demand without delay

The effect on his car was basically rev it up valve opens let the engine tick over and valve seems to take quite a while to close again so until it did the car ran badly. What was not clear was whether the ECU was keeping it open or if it was faulty, even weirder repeating the exercise on my car once fully warmed up showed my valve was not even being opened in the same way I semi wondered at the time if my ECU does actually open it at all and if so the bypass mod would be pointless!

I assume the vacuum pump opens it and some from of internal spring closes it, I wonder if the spring failed could the exhaust gas pressure force and keep it open for a while?

Certainly in his case blanking it off or fitting a bypass may be worthwhile

Anyone cut one up to see how the valve operates and check what sort of gas seal they have when closed?

Hi
I understood that the EGR valve opened when engine was only under light load,
ie it would'nt be getting nearly as hot as when engine is having to work hard in everyday running conditions anyway.

I don't know who wrote the text but I would say there is some very accurate data on the HonestJohn website as it comes from Manufacturers, Main dealers, Garages & Breakdown Recovery companies.
Oh well at least 260's don't have an EGR to worry about:lol:

That's what I said in the next couple of sentences. I didn't write the bit in the quotation marks.


The Egr valve has a hefty spring in it. When I removed mine I left it to soak overnight in some Gunk and then removed the gunge with a toothbrush.
It cleaned up as new.
I thought I'd check to see if was operating properly and hadn't siezed. so I inserted a piece of copper pipe in the exhaust gas inlet of the Egr and pressed. Didn't move a millimetre!! found that to move it required me to put most of my wieght on to it before it would budge, but wasn't sticking at all.
God knows how much vac. you need to open it?

The Intake mod lets the engine breathe better, but if you dont put in the egr bypass the air is hitting an equal reduction in size later, making the intake mod on its own limited in it's effectiveness, if not pointless IMHO.


Russ

So Much Garbage
 

I have never heard so much garbage talked on this forum about the EGR valve. I am so suprised that droves of R75 lemings are heading for the cliffs, based on half truths and miss-information, to the extent that they are removing a crucial bit of automotive design, in the mistaken belief it is costing them a few HP.

There seems to be this idea that the introduction of a small percentaqe of exhaust gases into the inducted air is going to increase the air temperature and not cool it, as Honest John & others have suggested.

IT HAS NOTHING TO DO WITH AIR INTAKE TEMEPERATURE!

IT HAS ALL TO DO WITH COMBUSTION TEMPERATURES - IN THE CYLINDER!

It is a great pity the majority of forumites do not understand the chemistry of combustion in a diesel engine.

The fuel takes as much oxygen as it needs. At low revs there is a surplus of oxygen, such that the flame temperature starts increasing as the fuel/air mix gets more diluted. Ultimately, this produces Nitrogen Oxides (NOX), which are not only toxic , but are bad for the environment.

The introduction of exhaust gases, which are low in oxgen, dilute the oxygen in the cylinder, thus reducing the combustion temperatures.

The suggestion that turbo bearings etc can be affected by these increased temperatures is perfectly valid. Even exhaust valves could be at risk.

People have suggested that disabling the EGR doesn't affect the MOT emmisions. This is only because they are done at max revs, where most of the oxygen gets used up correctly, so it is low in NOX's

The other misconception is when the EGR valve actually operates. It is supposed to be closed at idle, otherwise there can be erratic idling, which I'm sure a few suffer from.
However under full acceleration (wide open throttle), it should NOT be open also. At cruising where the engine is operating more effeciently then the valve should open, as controlled by the ECU.

So it is quite possible that by removing the EGR, cruising fuel consumption could be compromised.

So why many people are prepared to pay good money for EGR by-pass tubes , for the sake of an indeterminate increaser in power is beyond me. Although I will accept that at wide open throttle, then the marginal restriction could lose a few HP- big deal.

Leave well alone, but clean reguarly.

Colin

Cheers Colin for such an in depth knowledgable reply. Thank god I have not done this mod. No doubt someone will have a different opinion whos knowledge is greater than B**'s and Rovers technical gurus. BTW I will change my opinion if someone convinces me otherwise.

Nearly 40% of the air intake area is a marginal restriction?

NOX emissions are not part of the MOT test on diesel vehicles it is purely a smoke test.(but by the way my tester stated that mine had the cleanest emissions he'd seen in along time)

Fact: Egr systems reduce NOX emissions at the expense of power and fuel ecomony.
They are there to try and reduce emissions, they are not essential for the running of the engine.
There are probably more harmful emissions caused by a malfuntioning valve (which is probably quite common) and poor servicing and maintenance, than the possible small increase in the use of the bypass. After all only 6-10% of the exhaust gases are recirculated the rest goes out of the tailpipe.

The cleanest engines are those that use fuel and air in the correct mix at the right time to enable complete combustion.
Many people who have fitted the bypass have also fitted one of Ron's tuning boxes, so the engine is not in it's original state of tune.
It would be interesting to know the NOX emissions from cars fitted with both for comparison but these days I don't have access to an anyliser.

One thing I can say for sure is the car revs more freely with it fitted and doesn't struggle to accelerate when required as it did before, and mpg has increased approx 3mpg which is about 8%. Which is also good for the my wallet and the environment.


Russ

Any idea on the combustion temps that a non egr car reaches versus a car with a functioning EGR and how it compares to combustion temps on a turbo petrol?

Wouldn't like to comment on the combustion temperature differences between egr equipped vehicles and those without as it is not only down to that. It's also down to any modification, condition and tune of the vehicle.

Exhaust gas temps for a turbo diesel car should be between 650 and 800 degrees C under full load conditions.
The petrol turbo cars should be between 700 and 900 Degrees C under the same conditions.

Turbochargers will start too cook over 900 degrees C

The best way to minimise combustion temperature is to make the inlet charge as cold as possible. If your intercooler is semi-clogged then it isn't going to be as effective.

I've run turbocharged cars both petrol and diesel since they were first available the first being a B type engined SAAB 900 with an mechanical wastegate. (rather than the later variable type). I also currently have a Citroen Activa CT. I've run them in various states of tune and have never had a turbo fail due to overheating.
The only turbo failure that I've had has been due to poor maintainence of the oil by a previous owner.


Russ

Just found some more info. see: http://www.ias.ac.in/sadhana/Pdf2004Jun/Pe1131.pdf

On studies between egr at 0% and 21% open at different loads, show temperature differences of no more than 20 degrees C. to the exhaust gases. The effect on the combustion temperature therefore would not increase to over 900+ degrees C, that would do damage, unless there were other problems.

Egr systems also cause an increase of particulate matter(soot)that can have a detrimental effect on the engine and of expelled exhaust gases.

Russ

Great info chaps, the very reason I started this thread.
Seem to remember a while back someone on here did the Intake Mod and suffered a 3 BHP loss on the rolling road.:p:

More interestingly, no one on here has reported any diesel engine failure with all the available tuning mods...............yet.

Sorry, having done some reading and thinking and driving...I disagree...IMHO natch..:)

Further reading....since it is obviously a hot topic elsewhere too:

http://www.dieselbob.co.uk/tips.shtml
http://www.wynns.be/news.aspx?l=EN&i...iArticleID=826
http://www.aa1car.com/library/egr.htm
http://forum.landrovernet.com/showthread.php?t=62808 (Bless 'em :) Page two is most enlightening!)
http://www.pistonheads.com/gassing/topic.asp?t=243418

None of these mention damage to the turbo btw..

The whole EGR debate continues to rumble on.

I for one find it increasinly frustrating that there are so many people out there determined to by-pass them or turn them off etc when manufacturers spend so much time and effort getting them into vehicles to help reduce emissions with minimal impact on engine performance and so on.

I've just done some test work out in Italy on some diesel engines for emissions and fuel economy and also engine power and the results that I had with a "by-passed" EGR valve or failed unit as is would be viewed are amazing.

With the EGR valve working as it should the results were as follows:

CO - 0.306 g/km 41.3% of the limit for Type approval for this vehicle.
NOx - 0.323 g/km 82.8% of the limit for Type approval for this vehicle.
HC + NOx - 0.356 g/km 77.4% of the limit for Type approval for this vehicle.
PM - 0.026 g/km 52% of the limit for Type approval for this vehicle (particulate matter).

Then for OBD purposes, we have to fail the system or by-pass it to see if the system falls within the OBD limit requirements in this instance, it's fully open like a by-pass system would be.

The results are as follows (OBD limits are different, but look at what the TA limit comparison is) :

CO - 0.210 g/km 31.2% of limit. So far so good.
NOx - 1.783 g/km 457.2% of the limit - so massively over the limit!!!
HC + NOx - 1.859 g/km 404.1% of the limit - massively over the limit again
PM - 0.161 - 268% of the limit.

So as you can see, on a normal drive cycle for emissions testing the results go through the roof and are almost like running a vehicle from god knows how many years ago. Not to mention that the drivablility of the vehicle falls through the floor to begin with until the ECU "smooths" things out and then over a few cycles, the MIL will come on to show that there is a problem in the engine which is then stored in the memory until taken out and should you get pulled for a road side emissions check (which is starting to happen again very soon) they will be able to access your ECU and find out how far you've driven with a defecive EGR valve or other.

Fuel consumption also suffers on Phase 1 of the test by up to 1 litre in the urban cycle.

Keeping it clean is always a good thing as it improved efficiency, but bypassing it is a real no no in my books. MOT emissions sniffs are just that, sniffs and if you were to put your car through a proper emissions test like the one's I have to witness for type approval, your car would fail the emissions test. for either Euro III which all of our cars are type approved to and they wouldn't even get close for Euro IV.

Yes, they are predominantly there for emissions, but given the lengths manufacturers go to fit them into the engines and callibrate them etc with minimal impact on performance costs thousands and many months of development so I hope you can begin to understand why I and my fellow engineers who deal with engine development get totally hacked off when people start by-passing them all for the sake of a few BHP which you're never really going to notice.

Sorry, my 2p's worth but from where I sit, they're there for a very important reason. I hope you understand my frustration.

Nic

Everyone is entitled to their Opinion Rincewind (Nic) that is what this forum is all about.
You make some very Valid points,
But the modifications I have now made to my car give me 170BHP on the Rolling Road Tests and give the Car the power I like and it deserves.
I personally don't give a Hoot about Emissions (could be because I'm in the states so much),
If I get ripped off and have to pay all these green taxes then I will do as I see fit.
Only my personnel opinion of course, I don't recycle either.
Oops thats me off most peoples Christmas Card list.:D

Nothing listed on E4 either and no MIL Light.
Just sailed through MOT with ReMap, Rons Synergy, Air Intake Mod etc.
I have not de - cat it yet though.:D

I take your points Rincewind, however, many people with the egr bypass have non standard engines anyway. eg. Roverron module. Secondly, most people haven't fitted it for bhp but as a way of reducing smoke levels and to avoid reliability issues of what is, after all, an old-fashioned vacuum operated system that clogs up.

John, you will be lynched by the tree huggers...

Interesting. Anyone else had experience of reduced fuel consumption? My driving style and journey remain the same but my mpg has fallen a couple of notches (not good with current fuel prices!). I certainly haven’t had the +3 that Russ has (and I’ve carried out the air intake mod and PCV filter replacement).

When it gets a bit warmer I’m thinking of putting the original EGR back on to see if there’s any difference.

I know - sorry just having one of those mornings where I could happily grab the nearest person and rip their throat out for asking SFQ's as we call them (Silly Effing Questions as we call them) and some have been emissions related.

I'm not the greenest person out there at all and I do appreciate where you're coming from, it's just one of those niggly points that get's me back up a bit every now and then. I'm the first one (money permitting) in the queue for a V8 monster or whatever.

MOT is a breeze and any vehicle that's been maintained properly will walk it esp on the smoke side as the tolerance is quite high, but an MOT unit is not quite as sensitive as a full blown Horiba lab and AVL smoke meter plumbed in.

I'm going down the Rover Ron route soon but only up to about 150 bhp as I don't trust the bottom end on the 204D2 engine that we have in our cars to take the 170 bhp over a long period of time (hence the reason why Land Rover got the 204D3 engine IIRC that was a bit stronger).

Not getting at anyone, it's just the whole EGR things that makes me growl a bit.

Quote from Rincewind:
"Then for OBD purposes, we have to fail the system or by-pass it to see if the system falls within the OBD limit requirements in this instance, it's fully open like a by-pass system would be."

There are a few definitions I have to point out here:
A bypass system cannot be the same as an EGR held open.
As I understand it, a bypass "tube" completely blocks off any possibility of exhausted turbo gases re-entering the combustion

I'd like to see the emission figures done with the bypass "tube" fitted instead of the figures given above for an EGR valve held open. I'm sure that 457% NOx figure would be no where near as bad.

Finally how many EGR valves actually get cleaned in the car's lifetime by their owners or garages do you think?
Probably less than 10 %

So the 90% of clogged up (and many stuck open) EGR valves being driven
round the country are actually polluting our planet by that 457% NOx figure!!!
It can be concluded then that the device is best removed :shrug:

Oh and well said Zeb in post # 16

:iagree::wot:
Thats exactly what I was getting at!!! and from the information given by rincewind you can see that the particulate matter has increased too(with the EGR open) as I said.

A more effecient tuned engine can provide better economy if you don't use all the extra power!!! (Good fun at times though!). Better economy equals less pollutants released, probably lowering the total emissions by more than the small amount of extra NOx that the bypass would cause.

The small increase in the my fuel economy is a result of the combined effects of all the mods done to the car not just the Egr bypass.

JDC I'm with you on this one. There's lots of people getting rich on the back of recycling and environmental cost and taxes and it's at the financial detriment to the rest of us. The effect of which will make our remaining industries less competetive. The Chinese are building thousands of coal fired power stations with no emmision control (which is possible) to maintain their industrial growth. The U.S. foresaw the effects of environmental cost on it's industrial competetiveness which is one of the reasons it didn't sign up for Kyoto and it's slow uptake on environmental issues.



Russ.

There are some very valid points there if taken in the context of VW Group (as fitted in Galaxy TDi) and Renault diesel engines. Both the VW and Renault 1.9 TDi family of engines are very sensitive to blocked EGR systems. Lagunas and Meganes with the 1.9 and 1.5 DCi engines have a failure rate that would make you think they were fitted with chocolate turbos. But in truth, it is not the EGR system, or lack of one in the case of a bypass being fitted that is to blame. It is more a case of the inherent lack of long-term reliability and low operating tolerances of the particular breed of Garrett VNT turbo that is fitted to these engines.

The M47(R) engine is not hamstrung by this problem. Our Mistsubishi Industries turbo is as reliable as they come. I can recall many instances of 320d's, Lagunas, Golfs and Passats suffering from turbo failure. The Laguna in particular commonly consumes its engine oil through the turbine seals on an expired turbo leading to complete destruction of the engine. I have not heard of a single instance of turbo failure on a 75 or ZT. They have undoubtedly occurred but it certainly can't be considered a common or even infrequent problem.

In my opinion, the design and components of the 75/ZT diesel intake and exhaust system are of sufficient quality and reliability that bypassing the EGR has no detrimental effect to reliability whatsoever. The 320d may have had 150bhp as standard but they are known to be far less reliable as a consequence of the turbo fitted to generate that extra 15bhp.

Mod away fellas!!!

Go to Specsavers
 

To julesbass, Zeb, JohnDotCom, bigruss42

How on earth have you concluded from Rincewind's excellent information that bypassing the EGR has improved things?

His first and better set of readings are with the OBD system fully connected and the EGR working.

His second and worst set of readings have been taken with the EGR disabled, such that it never opens, and thus behaves like a bypassed EGR ie with NO injection of exhaust gases

To me, this only goes to prove that a good EGR system, can offer many advantages, not least of which is the vast reduction in NOXious gasses.

To me it's not an argument to compare you disabling the EGR with power stations in China.
The whole point about NOX reductions, is that they pollute the immediate environment. In areas of slow moving traffic, the engine is at part load and this is when the most NOX gases will occur.
So when you are crawling along, look across to the driver next to you, and just think you might be killing him/her as well as yourself.

This seemingly cavalier attitude at putting two fingers up to environmentalists, seems so selfish it is beyond belief. To even suggest that people are making money out of the green issue, while it is OK for people to peddle half baked and dangerous ideas, is really taking the biscuit.

It is only because of our very lax MOT, that enables you to get away with this.
Try it the USA, where most of the emmisions regs were born. I would think tampering with anti-polution devices would be illegal.

Thankfully, as some you may have read, EGR systems involving partial opening of the exhaust valve during induction are under development. Try disabling that!

And, as already been alluded to, it seems the main protaganists are the toys for boys brigade - enough said.

Colin

olin... I am not sure you and we are even reading the same thread.....I haven't drawn any conclusions from Rincewind's post....as to a cavalier attitude....I would suggest it is not a question of two fingers to environmentalists but it is a question of seeing many many companies hijacking green issues for profit...Prius anyone? When the EGR is closed it still does not behave the same as with the bypass fitted because said bypass does not restrict airflow whereas the Egr most certainly does.

Appologies if I mistakenly included you about Rincewinds post on his testing. However, it would be interesting to hear your views on his findings.
Colin

They provide food for thought, however, I would be keen to have a bypassed car emission tested against one that is standard and serviced as per the handbook. I suspect the differences might not be what people would expect.
My car is more efficient with egr bypass and does better mpg as checked over 10,000 miles. So any adverse increase in NOX etc is balanced by the fact that I am using less diesel in the first place and also, most importantly, releasing less particulates into the atmosphere - which I believe to be just as much of a danger as Nox...

I have now done nearly 20,000 miles with mine.
i have less smoke since removing it,
Ask Kandyman and julesbass who have previously experienced driving in my Wake of smoke,
now hardly any at all.
My MPG is far better than before and I have no faults being logged on T4 and as said have just passed MOT.
As to the Green issue, if I wish to put two fingers up to it so be it,
and frankly I don't give a dam.
In the US which I am in more than out, you would be so surprised at Modifications etc carried out.
Older vehicles can choke you to death following them with the black NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- coming out.
People over there regardless don't give a Dam about Green Issues where I go and will continue to run Air con everywhere 24 Hours a day even when not in, all the lights and flood-lights left on, cars that drink Fuel quicker than you can fill up over here.
They almost riot when it hits £1.23 per Gallon!
The US only Tax fuel at 39 Cents per Gallon!
So like a large Majority of people,
I buy the Things,
I use the Things
I will do what I want with anything within the Law of that Country.
And that is that.


PLEASE NOTE THIS IS IMHO AND DOES NOT REFLECT ANY VIEWS OF THE CLUB

On the contrary, altoghether too much said in my opinion, Colin.

Surely, if you wish to make a valid point or continue a balanced discussion,it is better to do so without making a sweeping and unjustifiable statement which will probably alienate the very people you are trying to convince?

I quite like having toys :) and, whilst the comment may have been meant to allude to a particular mentality (and imply a limited intellect) such stereotypical and sexist perceptions are in the eye of the beholder...;)

This Subject/thread does provoke strong feelings in People with their cars,
and the Green Issue in general.
After all it is their pride and joy next to their Homes, Wife, Children and Jobs not possibly in anthing like that order. :D

Colin, I certainly aren't one of the toys for boys brigade. The only reason for me fitting the EGR bypass and the Synergy was to help the engine be more fuel efficient, not to be some kind of "Boy Racer".
The effect of better fuel consumption reduces the emmisions from the car including the amount of NOx. I'll admit that the amount of NOx will be increased with the bypass than if the EGR were in place but would be nearly if not totally offset caused by the mpg inprovement with the added bonus of less particulate matter (soot and smoke).

Poorly maintained or faulty Egr valves are going to be far worse for the emissions than fitting a bypass ever could.

As stated earlier it would be very interesting to do a comparison between cars and see the overall effects, as Zeb said the results may take people by suprise.

By the way the statement I made about China had nothing to do with the Egr discussion.
Do you always twist things round to suit you own ends?

I suggest you re-read Rincewinds post in particular the paragraph just before the second set of figures. I think you'll find that it says: "Then for OBD purposes, we have to fail the system or by-pass it to see if the system falls within the OBD limit requirements in this instance, it's fully OPEN like a by-pass system would be." ?????

By fitting a bypass it completely closes off the pipe from the exhaust by blanking it off preventing the induction of exhaust gases into the manifold.


Russ

:wot:
Absolutely Sir!!!!!

In a world living with Genocide, child labour, industrial pollution and flagrant breaches of international human rights treaties, it is frankly laughable that people have the temerity to be personally offended at my use of an EGR replacement pipe. And for the record, my car is noticeably better on fuel and has far less smoke with the EGR replacement fitted. Less fuel used and less particulate matter produced. It may be robbing Peter to pay Paul as far as the Green lobby are concerned but the fact that it still produces far less greenhouse gasses than even the smallest petrol engined 75 can only be a good thing.

And that being the case, surely you have to care about the environment as well.

It's all getting a bit too heated for me. Anyway, is anyone interested in my EGR replacement experiment or not!! :)

Let's keep this on topic please folks, tangents leading to polluting the planet by other means is bound to cause friction so let's leave that conversation for the social forum. This is a technical discussion regarding EGR valves so keep to that please.

Yes, I'd be interested to know how you get on with the mpg experiment with the egr valve and bypass!

As I've stated on other threads, there are so many variables that affect mpg. Type and size of tyres, engine tune (including setting of Synergy if fitted), condition and maintenence, driving style, type of roads, wether you use cruise control , or just variables in manufacture.
What works on one owners car, may not work, or even have a negative effect on another.

I can only vouch for what I have experienced with my own car.

Russ

Russ,
I have re-read this several times, and I cannot come to any other conclusion. Perhaps the author could clarify it, but I read it as having to bypass the system, not in a mechanical sense, but that the control to the EGR is disabled, such that no exhaust gasses are introduced in the cylinder. In other words, without having to remove the EGR completely, it simulates the bypass much as removing the vacuum from the M47R's EGR, which is what many protaganists advocated before the introduction of the by-pass tube.

I have to assume that the second set of results, is trying to demonstrate the effects of no EGR, which will show up on the OBD. If not, why then the does he quote the figures.

If you still don't believe that, lets ask the man himself.

Colin

Precisely, one would hardly buy a Rover 75 diesel if one were a "boy racer".

I was finding this thread very interesting and it was providing food for thought and a greater understanding of how our cars work.

However, if somebody chooses to tar me (and many others) with a certain brush and place me in a given pigeon-hole based upon no evidence whatsoever, other than having had the temerity to fit an EGR bypass then I must wonder if their hitherto apparently objective comments might not now be viewed in a different light.

Might we please avoid the somewhat personal attacks against an arbitrary group and return to the objectivity which made this thread the interesting read it was please?

Given time for reflection, an apology might be appropriate, if not forthcoming as well I think.

OK Paul but this is not a court of law it is an internet forum. Discussions are as they might be over a pint in the pub. Slightly heated with a modicum of frustration thrown in for spice. Let's all keep some perspective please.

Fair enough Mick, but where I drink, people either have the wherewithal to back up what they say, or the good grace (or sense of self preservation) to back down. The alternatives being unthinkable. :jedi: ;)

Don't you find though, purely general terms, that people will say much more from behind a keyboard than face to face? :shrug:

Oh No I'm far worse face to face believe me.
As long as I know what I'm arguing about to be correct I won't let go I'm afraid. :D

As in going to a local school to complain and have a Constructive discussion on Ba Ba Green Sheep I ask you.
The NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- things around here are either Black or White never yet seen a Green one even after the Russian Nuclear Disaster. :D
I actually had my Granddaughter ask WHERE The green ones were, so Off I stormed.
At the Parents Teachers meeting I in the end managed to get them, with backing, to proper facts, not Politically correct Garbage!!
Rant Over Sorry,
Back to Thread.

Or perhaps I should have said (without managing to confuzz myslef) we bypass the EGR system in a number of ways so that it doesn't work full stop.

The OBD limits have a much higher limit than the figures used for a "standard" European drive cycle. The numbers that I quoted for the second test are a long way under the OBD limits but after the calculation in relation to the legislatitive EUIV limits, you can see how much above the limits the vehicle is.

Having witnessed many emissions tests on diesel and petrol vehicles with EGR, the results speak for them selves. As I've said, I'm not exactly Mr Green (lord knows I'm not having poured more fuel than I've ever poured into a car whilst doing the European and American brakes testing on the new Aston Martin DBS - 2.9 mpg anyone??? and loved every single second of it!), but I hope that people can understand a little about why EGR's are so important to a vehicle in todays engine installations. If they were really as bad as people perceive them to be then manufacturers would seek other alternatives, but as they don't really affect engine performance that much, why bypass them?

Lively debate though isn't it!

I admit to not fully understanding the workings of the EGR valve, but I can't find anywhere in this thread where the tests actually use an EGR BYPASS, as sold by Wingy, and fitted to many owners' cars, including mine.

The tests seem to be with EGR "disabled", or "disconnected", but still in place. Do the tests referred to include any with a bypass, as I thought part of the idea of the bypass was to remove the lump of metal partly blocking the pipe?

Forgive me if I've missed something.

Thanks

Malcolm (aka "confused of Tring")

I suspect that the perceived wisdom of impartial readers of this forum will have changed. As one with no axe to grind either way, mine certainly has.
I recently removed the EGR valve on my ZT-T and found the huge build-up of crud (five years old, regular dealer service, obviously never been cleaned). So I cleaned it (not difficult) and then pondered whether or not to get the by-pass and avoid the chore for the future.
Having followed this thread, I have decided to stick with what I've got.
If it ain't broke don't fix it - just clean it.
Di.

Thanks for your clarification Rincewind.
I am man enough to apologise for any wrong conclusion that I may have reached by my mis-interpretation of your statement. From it I had gathered that the Egr valve was open allowing exhaust gas into the manifold in the second table. I was concerned however that the amount of particulate had increased as I thought that with a rise in nox this would have reduced?

The things that bother me are that with the EGR bypass fitted the car runs smoother and pulls better(even with the Ron box turned off) and that the fuel consumption has improved.
Emmision issues aside the average +3mpg that I have experienced equatates to an improvement of around 8% which is by no means an insignificant amount. I have also witnessed a reduction in smoke.

From the posts others have found this too. This cannot surely be a fluke. Either the egr system on our cars were faulty in some way (mine seemed to be free enough with no sticking or bad seal) or that there may be a genuine improvement by fitting it when combined with the other modifications.

At least we can gather from this lively (and hopefully) informative dicussion that evryone will have their own thoughts on this, to which they are entitled. Gather your own conclusions, should I or shouldn't I, it's completely up to you, it's down to personal choice.

Personally I'm very happy with the improvements and the change in performance that these modifications have given the car. Especially the improvement in mpg.
If it has increased some emmisions slightly then so be it, but there again I don't sit in commuter traffic, or run the kids 300 yards to school in a whopping big gas guzzling 4x4.

And anyway will anyone give a monkey's in 100 years time to any of this .....

Think about it;)


Russ

At the weekend I removed and cleaned my EGR valve. It was the usual 4-year old build up of crud! I decided to disable it by blanking it off (with a "custom-made" cut-out piece of tuna-tin lid!!) and blanking off the vacuum tube. I also cleaned my MAF snsor and PCV valve. I haven't noticed any discernable difference in the few miles I've done so far but if there is any significant improvement/detriment I'll be sure to let you all know.

Well Im going to get an EGR bypass, purely in the interests of economy and performance. Look at the restriction that the stock EGR valve has and you will see why. Its a fact that increased airflow leads to increased efficiency and performance.....and thats enough for me.

Also after having seen the amount of crud that accumulates inside the egr, id rather blank it off thank you very much.

Who's Rinceweed :sissy:???

Name Corrected Nic,
to protect the Innocent. :D:D

Honest John is talking rubbish. He has no proof at all and any engine that relied upon the egr system for reliability is a liability.

Here are the facts which make nonsense of his waffle:

a) Exhaust gas recirculation was introduced in about 1996 as a NOx and HC reduction strategy. Presumably therefore, manufacturers all redesigned their engines to 'need' a functioning egr system to be reliable? I don't think so! The reduction in temperature is not significant for engine / turbo reliability, it is simply the way the NOx reduction is achieved. If significantly higher temperatures were generated with no egr system, the cooling system (water and oil) would take care of the excess heat. (Has anyone noticed their temperature guage reading higher since removing the egr valve)

b) It ONLY operates on part load - above 60% it is disabled which is the very time the engine is working harder. Yet do owners towing caravans (when average load is much higher) suffer from reliability problems?

c) As far as disabling v removal is concerned. the reason for removing it is because the valve assembly obstructs the airflow. So disabling it is not the same as removing it.

d) Find me anyone who has had a problem with their Landrover Td5 (egr bypasses have been on sale for years for these), TD4, 75, ZT, BMW who has
had a problem that can only be explained by a non functioning egr system.

Whatever your views on pullution/green issues, the egr bypass is effective at reducing smoke (particulates) and by improving fuel efficiency, CO2 as well. Personally I see these two pollutants as being more important than NOx.

Ron

Did I mention the trusty maf sensor?

Used by the ecu regulate exhaust gas recirculation in addition to fuelling. (On many engines it's only function is egr control)

What happens after as little as 30k miles? It goes out of spec, ruining the emssions anyway.....

No doubt it is this unreliability and unpredicatbility that is the thinking behind switching to a lambda sensor to measure the exhaust oxygen level or the use of the heater plug tip to measure cylinder temperatures.

Ron

It would be interesting to look at egr valves from other types of vehicle. I have no plans to remove mine but it is obvious to me that the design of our EGR does provide a significant breathing restriction.

Would it have been so much more difficult to put the valve and accuator on the pipe providing the exhaust gases rather than directly in the line of fire of the airflow from the air filter?

It also seems to me that if the egr has a build up of carbon deposits then so too will the inlet manifold and the backs of the inlet valves, none of which is going to contribute to maximum economy or performance.

Andy

To RoverRon

Ron,

I am very suprised that you of all people have fallen into the same trap as many others.

To avoid elongating each reply with your statements, I will address the points in your post.

A/ EGR systems have been around for a lot longer than that. I first saw them in the 70's, albeit on petrol engines, where yes, they caused a bit of pain getting gummed up, but in those days they were less sophisticated and could not be by-passed. The cars that did have them, were only those that were sold to the then USA emmision requirements. The introduction of EGRs to diesel engines IS relatively modern, but the issues remain the same.
I am afraid you, amongst a lot of others, appear to have not understood about this temperature issue. It only relates to the instantaneous flame temperature and not the average temp of the engine. Surely you must know that a petrol engine running too lean, can burn out exhaust valves, with the engine temp perfectly normal. So, to try and make an issue of no EGR doesn't give rise to increase engine temps is extremely misleading.


B/ Yes I agree it is only on part load, but as you well know is dependant on many factors, such as throttle position, revs etc. So the amount of recirculated exhaust will vary according load. If caravan owners are working their engines harder, and the EGR is effectively off, what is your point about reliability. As you well know, the turbo will be providing partial to full boost, the products of combustion are different, so there is no issue with heat, flame temperatures, NOX etc, reliability is no different.

C/ It is obvious that disabling it is not the same. However, for the purposes of showing what happens to none functioning EGR systems or seeing what happens without it, it clearly is an easier option. Where I will take issue with you, is on this so called obstruction. It is all very well to measure the total areas and conclude that there is this 30% or so obstruction. As you should well know fluid mechanics don't work like that. It's a bit like saying a 3 bladed wind turbine can't be as effecient as a multiblade one. But it is. You might as well say a carburettor obstructs the airflow, but of course the air speeds up through it. If we were talking about a normaly aspirated engine, where ram air was vitaly important, then yes I would agree with you. But we are not. The turbo starts to work fairly early, so a minor obstruction is not going to make a huge difference.
Has actually anyone done a dyno test, at all engine revs, with the EGR in place and working. Then immediately removing it, replacing it with the bypass and repeating the tests. The reason I ask this, is becuse there seems a lot of talk, eg "The car feels different etc, etc ", which I quite frankly don't trust - ie a placebo effect.

If such tests have been done, and verified, then they should be published for the whole world to see, then at least some of the arguments could be stiffled.

D/ Again, how on earth can that be verified - where's the back up data?

It's all very well to say that you prefer to curb CO2 and particulates in preference to NOX, that I'm afraid is an invalid statment - perhaps a conflict of interests perhaps?

Colin

Sorry about the un-intentional name change Rincewind, but it was getting a bit late.:o

Ron, thanks for reinforcing the points I was trying to put across in my previous posts.
Especially the one concerning the reduction of particulates, for those concerned with the environmental effects of fitting a bypass.
Because it's very difficult to reduce NOx without an increase in particulates, it's a balancing act.
For those who don't know what the harmful effects of these are, I suggest you have a look at:
http://www.arb.ca.gov/research/diese...ft_3-01-06.pdf

Your products and those you have helped develop, do you credit and in my opinion the results that myself and others have experienced, should speak for themselves.


Russ

And who do you think helped Wingy develop the bypass? Guess !


Russ

Yes I did test it for him, but I have no commercial involvement. and am sorry that Colinw thinks I'd sell or recommend any product to make a few quid knowing it to cause damage.

Ron

To Colinw.

Julesbass started this thread on the reliability issue so that's the basis of my reply.

Yes, the exhaust gas displaces O2 and reduces flame temp to reduce N0x
and no, I haven't overlooked the flame temperature's part in NOx formation. Its just not relevant to engine / turbo reliability as part of the egr system because it has little effect on overall engine (& turbo) temperature.

If it did have the effect HJ claims, manufacturers would have:

a) modified the engine / turbo to cope with a malfunctioning egr system due to faulty maf sensor.

b) Made the maf and egr valve service items.

c) Caused the MIL to come on and stay on if the ecu detected incorrect egr
operation.

d) Printed a warning in the vehicle handbook regarding the importance of correct operation of the maf / egr system for engine reliability & warned against tampering with it.

Ron

Well as Stated I have one, Including a ReMap and A Brilliant Rover Ron Synergy Unit, a Rover Ron Turbo Spring Mod, Air Intake Mod MK2, New MAF, Upgraded Air Filter, 170BHP on Rolling Road Tests. Etc Etc.
It can keep up or exceed the 160's 180's etc with its Great Torque.
The Point?
I'm very, very Happy. I am not a Boy Racer.
I get Brilliant Performance, Great MPG, a lot more than many on here without the Mods,
I travel 40,000 Miles a Year and have no Complaints what so ever.
At the End of the Day whilst it is legal to do so I shall continue to drive (cat off next) with all the Declared Mods.
On a Vehicle Weight/Emissions Traffic Check Station, Manned by Police, Ministry and DVLA etc outside Chester,
I enquired about these Emissions, with the Officers there in Charge of checking the lorries and Cars (ex Job does help) I was told:
"If your Vehicle meets the MOT figures as Set down for your car and is does not have excessive smoke, we will always Pass it. Yours has nothing to worry about and is easily inside said printed figures for your Vehicle".
Not sure what I would have done if it had failed.
I rest my Case.

We are fortunate in this country to still have the freedom to make mods.
In Germany unless a product is TUV approved it can't be fitted.
Even bikers suffer because they may not use a make, type and size of tye not TUV approved for their bike.

Needless to say gaining TUV approval costs thousands. We probably have the French to thank for stopping the Germans making TUV approval mandatory across the EU!

Ron

Well, that's one small merci we can be thankful for ;)

Clearly, I couldn't possibly be a party to anything illegal as far as my car is concerned so I'm pleased we are not yet quite the Police State some would have us be.

6000 miles now with the EGR bypass, amongst other mods and very happy with it :D

I'm not a boy racer either, in fact I go faster in my zimmer frame.

Gets popcorn

http://img337.imageshack.us/img337/6...popcornci8.gif

Well that's a different subject, removing the cat, John
Think I'm right in saying you would have to refit it every year to pass the MOT tests. I couldn't be doing with messing round like that.

lively thread isn't it?

Any views on the subject?

Russ

Hi Jules, the Cat Removal makes no Difference on the MOT for Diesel at all, with it fitted or Not.
Work that one out?
I'm sure someone with the Technical Answer will be along shortly.

I have been following this thread with interest and I can clearly see and understand the points raised both for and against. (my Egr is clean and connected by the way) My understanding of the reason Egr’s were devised and installed is to help reduce emissions. Does a free airflow coupled to a clean Egr reduces the particles expelled. Or are the reductions achieved due to the EGR bypass? When MOT testing almost every emissions test failed for excess black smoke can be linked to dirty filters and a pass achieved with no work on the Egr. This would lead me to believe the former.
The argument for particles has been put but what about the gases? Please read the article below then take a minute to weigh the major affects this would have upon the world if we all disconnected or bypassed our Egr’s, when measured against the small personal gains we achieve.

Although I am not a tree hugger, I am somewhat concerned for future of my kids and generations to follow, by people’s attitude towards emissions and the effects that they have. IMO we seem to adopt the attitude that the death of our fantastic planet or the deaths of the people on it won’t happen in our lifetime therefore it’s not our problem.

By the way just to fuel the debate, consider this. When compared to the gains achieved solely from the Egr modifications, you would probably achieve better gains and lower emissions by using modern premium brand tyres, with the correct pressure, coupled with the tracking correctly set.

By the way I agree with the views regarding the tosh written on the honest site (he should think up another name) answers on a postcard please.

Ron,
I didn't mean it like you read. I meant - as you are involved in selling products to improve/correct performance, it is difficult to give an unbiased view of the NOX versus particulate/CO2 argument. Your'e allways going to favour improved performance.

No way would I ever suggest that you promote something that is instrinsicaly unreliable or would cause damage.

To be honest, I had forgotten your involvement in the bypass tube - so that's another yellow card then.

Now back to your response:- Yes I agree with most of what you say, particularly as it is couched in terms of a wish list of what should happen.

So, having said that, wouldn't it be more beneficial to put our collective minds together, to try and make an EGR valve which not only satisfies the need of the extra BHP lobby, as well as us environmentalists?

Of course I know what your'e going to say. The motor industry has poured countless billions into this endeavour, but hasn't really come up with very much that is easily implementatble. I have even read that Propane injection is one thing tried, as well as the exhaust valve cam, partially lifting the valve to send some of the exhaust straight back.

So, how about an EGR, which is capable of injecting the exhaust gas, after it has been scrubbed, by allowing it to go thro' some form dispensible filtration, such that it is clean gas, which then can be injected much like gas conversion systems do. This will achieve all our aims, reduced NOX's, easily disposed crud and maybe just maybe a few extra HP

I know this is brainstorming a bit, but it's better that the two camps always agreeing to dissagree.

Colin

Many engines have the egr valve connected directly between the inlet and exhaust manifolds so there is no obstruction of the intake air path. Rover's L series is like this and features a water cooled heat exchanger which serves double duty as an exhaust gas cooler and as it is plumbed into the heater circuit, a slightly quicker heat output from the heater.
It is a pity BMW have not adopted this method.

A correctly operating egr system of the above type should have no impact on performance since it will close as soon as you accelerate. However, regardless of how good the egr system is, whilst a maf is used to provide control of it, it will never be guaranteed to work trouble free.

Mondeos & Jags suffer from judder at 1800rpm due to the egr valve, or more likley the maf sensor. So owners fix the judder by disabling the egr system. This happens on the L series and BMW engines as well as countless others.
Yet no one experiences engine or turbo reliability problems, to get back to the orginal topic.

As far as a new system goes, any that could be devised will need a more accurate control method such as a lamda sensor and possibly engines with these will not suffer from egr related issues. Time will tell.

In conclusion, the egr system currently in use is fatally flawed becaue of its dependance on a 100% working maf sensor. Therefore you may as well disable it or remove it once 30-40k miles have passed unless you are prepared to fit an OEM maf sensor every 30-40k miles and keep the egr clean and leak free.

LPG fumigation does work on diesels but isn't worth the trouble and expense on small engines. On trucks, apparently it is, giving much reduced emissions and better fuel economy.

Ron

No, it not tested for.

Its only a simple oxidation type intended to get rid of the obnoxious diesel smell (partially burned HCs) . It does little if anything for the emissions hence its not tested.

Many L series owners fit decat pipes becaue they are a simple bolt on fitting.

Ron

Hi,Tigerchubs, hope everythings o.k your end.

Regards,

Russ

Yes, in the UK you can make modifications, it's Europe where the problems start as Ron has pointed out very well!

The TUV are just a test house they are not quite the same as a type approval authority - it's a difficult subject to write about.

A simple TUV mark is not necessarily a route to approval. What you're looking for is a "E" mark on a component. The TUV do the testing to the relevant legislation and then it's people like RDW in Holland and us (the VCA ) in the UK that approval things for sale. No E mark, no sales. In the EU this is manadatory, the TUV are just a testing organisation.

In the UK, it's type approval engineers such as myself that have to ability to say if a product is fit for purpose to the relevant legislation and only then can a product or component be put on the market to be sold with an E mark, in a nutshell, if anyone wants to apply for an approval on a component so that it can be sold in Germany, France, Italy or anywhere in Europe it has to come through a relevant authority.

A vast majority of the time anything from the TUV comes through us at the VCA and we check that it's all be tested correctly then we issue the certificate. If it has an E11 approval mark, then the VCA have issued it.

I'm trying to find time to write about it all and get something published so people can begin to understand what we (Type Approval Authorities) have to do in order for anyone to get their products to market.

Nic

171BHP / 313lbft
No EGR
No CAT
No smoke (as such)
MOT pass with very low emissions
better throttle response
better MPG than standard and I have had the car from new
tried and tested on the road, not in a discussion/lab
Very happy bunny


just my point of view of course.................(gets flak jacket)

:iagree::wot: Almost same as me. :lol:

Just out of curiosity, and I'll fire up a new thread if necessary, could people tell me what they think an emissions test consists of. By that I mean, where do all of the numbers come from, Be they CO2 etc or MoT.

Anyone in the auto industy that does the tests, or are familiar can't answer - that's cheating!

Just curious that's all no finger pointing or owt like that!

Nic

Diesel smoke transparency on full throttle, the average of a few runs.

Hi Ron,
to clarify, are you saying that the catalytic convertor on the diesels does not reduce / eliminate the NOx produced?

Kearton

I just thought the engine was accelerated up to a governed speed when up to Temperature,
The Smoke density is then measured, engines that are emitting very little Smoke and return a metered figure around 1.5m (to-1) on first acceleration Pass, if it fails Two more attempts are allowed. The Cat on a diesel does not effect this one bit so removing CAT is no problem, and as I don't like CATs thats fine with me. :D
The average of these three attempts should then be below 2.5m for Non Turbo cars and 3.0m for turbo charged cars.
You also receive a Print out of readings from most MOT stations now.
A Diesel car in the UK should fly through this easy Test if car serviced and Maintained.
Now Nic will tell me my Summary is a load of old Cobblers!

On a slightly dofferent track.
An Interesting thing when at my Brothers Garage was, he said my CO2(g/KM) were reading at 177 G/KM on his Computer Readouts (certified systems) so I'm told, and yet my Registration Documents say 190 G/KM which means my car should be in a Lower Tax Band.
If I send off Print out would it be reduced?
Nic can you explain that puzzle for me please?
or is this another way the Government are ripping off the People. :(

It's sole purpose is to oxidise any partially burnt fuel (HC) to get rid of the orrible diesel smell of yore, thus making the diesel engine more acceptable for use in cars and for other road users.

As an oxidising catalyst, it would actually make NOx worse if it was able to reach high enough a temperature.
(It is the oxidising effect of excess O2 (+ high temp) in the combustion chamber that converts Nitrogen into NOx.)

Ron

I think the testing method used has changed. When my 96 Relay camper was tested in August, it was just revved up 3 times very briefly - didn't sound to even have reached max rpm either. It wasn't held at govererned speed as used to be the case.

Ron

You tell us please!

It seems to me that a roadside emissions test is not necessarily the same the MOT test. Ie. MOT is smoke (particulates), whereas a roadside one could be
CO, CO2, HC, NOx.
I'd guess that for petrol vehicles they are looking for signs that the cat / lambda sensor are working, and for diesels, particulates.
I.e there is no point in looking for emissions the driver cannot put right by changing the cat or sensor. (& in future, the particulate filter)

Ron

If a diesel car does fail the MOT emissions, a can of Wynns (the type that is put neat straight into the fuel filter) works a treat.
Far more effective than the products that get diluted in the tank.

My sister's old 600 GSDi (80K miles) usually fails every year (think she drives it to carefully!)
Can of Wynns sorts it out every time, now we tend to put it in BEFORE the test just to make sure she passes;)

I know people who have had a huge bills from a garages to get it to pass the emissions.............that's probably all they did to it.
(costs about £7 a tin)

Now the 'particulates' have settled, but not wishing to fuel the debate again,
those of a technical disposition, may wish to peruse the document linked below.

In a nutshell, it would seem that maximum effeciency AND high values of EGR ARE possible. So if anybody is into re-mapping, we could ALL be very happy bunnies.

http://www.ornl.gov/~webworks/cppr/y2001/rpt/122004.pdf


Colin

First up before I delve into how emissions tests are conducted, here are some test results from a diesel engine with a catlyst and then the results afterwards are the same vehicle with no catalysts (like a de-cat).

Test with catalysts.

CO - 0.149 g/km 22.1% of TA limit.
NOx - 0.311 g/km 79.1% of TA limit.
HC + NOx - 0.335 g/km 78% of TA limit
PM - 0.026 g/km 44% of limit.

Test with no cat (de-cat).

CO 2.014 g/km - 299% of TA limit (a smidge over!)
NOx - 0.317 g/km - 81.3% of TA limit
HC + NOx - 0.537 g/km 125% of TA limit
PM - 0.032 g/km 64% of limit.

So as you can see, not having a catalyst increases the results by quite a bit.

Right, the fun bit. Here's how you do an emissions test on a vehicle to get the CO2 figures, fuel con and smoke numbers etc.

Firstly the car is coasted down from 135km/h to 0 in neutral on a flat surface with minimal wind and done in pairs, say north south and so on. Usually about 20 pairs to give statistical accuracy to see how long it takes the car to slow between timing gates. 125 - 115, then 115 - 105, 105 - 95 and so on all the way to 0. The time taken for each 10km/h gate is then fed into a calculation that gives me the power absorbed by the vehicle at given speeds so that a set of dyno co-efficients can be created to "mimic" driving on a real road in a lab. This takes up to 4 hours a derivative depending on weight, engine and gearbox configurations.

From there these numbers are fed in to the road dyno in a lab. These dynos cost upwards of £300,000 depending on what you want, 2 wheel or 4 wheel dyno. This dyno forms part of the emissions lab with a drives trace and all linked up to in excess of £1.5 million of exhaust analysers with "bags" to sample the entire drive cycles from the vehicle (a little more complex than an MOT sniffer!).

A car is then pre-conditioned over a given drive cycle (I'll explain in a sec) and then left to "soak" for minimum of 6 hours so that the oil and water temps get to within + or - 2 degrees C of the soat temp which has to be between 20 and 30 degs C.

The car/van etc is then placed on the dyno after the soak without firing up and the analysers are hooked up to the exhaust pipe(s) and the dyno is set to the given road load conditions for the vehicle being tested.

Depending on fuel there are then a series of tests done.

For petrol, you have to perform a Type I, Type II, Type III, Type IV, and Type VI test (I'll explain more) A type V test takes 80,000 km to do and ages the exhaust/catalyst to determine deterioration factors for the Type I test.

Diesels have to to a Type I test only and smoke test.

Right, Type I test.

vehicle is driven over a test cycle. Part 1 the Urban cycle which covers 4km and a part 2 Extra urban that covers 7 km and the whole thing takes 1180 seconds to perform. All of the gears are used and in the part 2 the vehicle gets to a maximum or 120km/h and at the end of the test the bags are analysed to give you the final figures for CO, NOx, HC, PM etcs. This is the test that produces the figures for the tax bands for the car an also the Fuel con figures that are published.

From start to finish the test takes approx 30 mins from vehicle check, drive and anlyser results.

For a diesel engine, filters are placed in line with the dilution tunnel that the gasses pass through so that the particualtes can be collected and measured. There are 4 in total, 2 for part 1 and 2 for part 2. These are weighed pre and post test to find out how many particulates are produced over the drive cycle.

A petrol and diesel engine both have to do this test and I have to monitor the drive cycle and make sure that the driver stays within the speed tolerance band during the test.

Type II test (petrol only)

This is what you guys know as the MOT test. The test is conducted after the Type I test. The gas anylsers are programmed to read the gasses at idle and then fast idle to create the CO and Lambda figures for the car at a given oil temp. These numbers that are recorded end up on a wall in an MOT test station.

Type III (petrol only)

Crankcase ventilation emissions. This test is done to make sure that the engine is sucking and not blowing. Test points are fitted to the manifold and crankcase breathers to make sure that the engine is doing what it's supposed to do at idle, and then at 50 km/h 3rd gear under no load, load and extra load all done by the dyno.

Type IV (petrol only)

Verifiying evaporative emissions from the vehicle - takes 24 hours and the vehicle is driven over a Type I test and then sealed in an emissions chamber to monitor what if anything escapes from the fuel lines, tank etc. The max limit of emissions is 2g in 24 hours!

Type IV test (Petrol only at the moment soon to include diesel)

-7 deg C test. Car is preconditioned on a drive cycle then kept at -7 to pull oil and water temp down to -7 then using the same drive cycle as Type I test the car is emissions tested.

Type V test is done to determine the deterioration factors that allow me to do a calculation for the emissions from Type for an aged catalyst as it would over it's life time - either done on a track, ir dyno (80,000km soon to become 120,000 km.

Smoke test for diesel - this is usually done after a drive cycle. The analysers again monitor what's going on with an additional pipe for smoke absorbtion. The free accel test similar to that in an MOT detartmins the smoke figure that goes on your car. There are usually 10 to 12 accels. The first few are to "clear the sytem" then the final 6 results are taken for calculation purposes. Then these figures are correlated with the engine power test that will have been done on an engine test bed at given rpms to sort the engine power and torque figures out. The numbers are then linked to steady smoke and at the end of a lot of number crunching the smoke figure is produced and homolgated for the car - for us with our MG's and Rovers, this is prob on your VIN plate as either 1.00 for a 116 engine or 1.33 for a 131 engine.

An MOT sniff and smoke test is a generic on that has a huge tolerance band of around 3 I think so pretty much any well maintained vehicle is going to pass and it's not done in the smae manner as the emissions tests that I have to do.

This is only the tip of the ice berg and given how many vehicles a manufacturer produce, every engine and gearbox has to be tested to produce the figures. I've missed bits out as I could take forever to write it all out for you.

When printed out on A4 in a usual 12 point font, the legistlation for emissions is just over 1 inch think and I have to know it pretty much inside out.

So as you can see, what you get in an MOT is nowt compared to what I have to approve for the industry.

So winding this all back to the whole EGR de-cat debate, if I were to take a car with an EGR bypass, or EGR and cat bypass, do a proper emissions test on it, it would fail the emissions test regardless end of story no quibbles about "it runs better, better mpg less smoke etc", it would simply fail. The emissions test in an MOT station is a basic health check and nothing else. Nothing is tested under load or with a reference fuel on with clean filters ever time or on a massive HORIBA or AVL emissions kit and dyno costing millions of quid!

So John, your car measured at 177 g/km CO2 is done on a static rig an not over 1180 seconds using all of the gears on a dyno etc. Your car was homologated to a given figure for the type approval of the car, so you couldn't lower your tax bracket based on one test, it would have to go into an officially approved lab.

Phew, my fingers hurt.

Having said all of that, it won't be long before I get one of RoverRons boxes and strap it to the car as I want some more bhp and torque to play with! I will however, be leaving the car and EGR in place.

Hope that helps answer a few questions.

Nic

Colin, very interesting reading, it proves that it can be done.
No doubt that cars built in the future may utilise this, and this is a very good thing too, I'm all for it, although I feel to do this on a Rover 75/ZT would be next to impossible.

It wouldn't just be a case of re-mapping the ECU. You'd have to completely redesign it, the manifold would have to be altered to incorperate a throttle valve, the actuators for this would have to be wired in and configured with the ecu to work correctly. and a heat exchanger fitted to the egr inlet to reduce the temp of the exhaust gases.

For those who are looking at things from an environmental point of view, in particular the use of re-newable fuels as a cleaner alternative, may find this recent report into the possible health effects from emmisions using rapeseed oil as a replacement for diesel fuel disturbing. (it's only an extract you have to pay to get the whole thing)
http://www.springerlink.com/content/j2450768j54xr5t5/


Russ

hmmm. what a good thread to come back to. last link is pretty disturbing.

Best summary: enjoy it while it lasts. Its just not worth worrying about the different perceptions of the developed world when there are a thousand times the density of humans coming on stream just sampling the joys of the Carbon economy for the very first time. We haven't a hope.

From the contributors so far, 'it' will variously be perceived as car, fuel, or planet. As the wizened old scottish one from Dad's Army said: 'Weeeee'rrrrre doooooomed...' Last one out please turn out the lights.

Is that wizened as in wise or wizened as in wrinkly?:)

Andy

So those measurements are not what I'd call real world, though that's not to say I disagree with them and I've never claimed that removing the cat or disabling the egr system doesn't have an effect on emissions.
But my argument is simply that the majority of diesels with more than say 50k miles on the odo will to some extent, have a malfunctioning egr system due to maf deterioration.

In other words, if the 'powers that be' were concerned about the emissions deviating from theoretical, they would have required the egr system to undergo specific testing during the MOT, and require manufacturers to include it in routine servicing, make the maf a service item etc.
(I can understand them not checking for the presence (or effect) of a cat as they would never think that anyone would remove it!)

Engines are becoming more complex to meet stricter emissions regs and the M47r in BMW cars has swirl inducing flaps in the intake manifold (which have been known to break off and end up in the combustion chamber), others have flaps in the exhaust system, fuel heaters, intake air heaters, etc.
Ron

Cor...lummee guv....lots of angry chest beating going on on this thread, and I suspect that the site has been invaded by a BMW owner?

I stand with ZEB, Johndotcom, RRon and Ti Rich here.

If you havent done the modification to your car how can anyone possibly say it doesnt work?

I have followed the path of darkness and fitted the EGR along side RR mods the result is indesputable...

More grunt
Better MPG
Less Smoke
Clean MOT pass
Wider power band
More Low RPM grunt

and no.... it hasnt blown up yet...despite the fact that it has been provoked to do so.


:sissy:

I understand what you mean about real world, but these results are taken from a vehicle that I homolgated for manufaturer 4 weeks ago. The results are taken from the ful blown 70/220/EEC emissions directive that everyone has to take when manufactuing a vehicle. The results come from the drive cycle that is a totally repeatable test.

Now you might say that they're not real world, which in one way they're not. If we were to take a real world result, they would be much higer than that as no one drives to the required drive cycle.

The point that I'm trying to get across is that an MOT test is a health check only and the EGR/CAT systems do not function the same as they do under a legislative testing proceedure. If you were to have the same test done for an MoT, your test would cost around £300 to £400 every single year to find out if your vehicle is still operating within the tolerance allowed under conformity of production rules.

Becuse the engine is in a different condition at an MoT, you'll never know what you're engine is putting out of it's exhaust.

And correct, there engines will deteriorate over time, which is why we test the way we do to inculde deterioration factors in the results for aged catalysts, EGR and any other part of the emissions system requirments.

Nic

Nic

i don't think that anyone is disputing that fact that the mods don't work, the debate is on what an MOT test is and how it is affected by EGR's, cats etc and then the full type approval testing proceedures and looking at the comparisons between the two.

(I think)

Nic

I understand your current debate with Ron...I was refering to the thread in general...considering its such a tiny issue in the scope of things....I mean...mine still passed its MOT cleanly and surely there are worse polluters than the humble CDTi...with or without EGR bypass.

Mine is not to dispute superior knowledge here Nic...I just think the thread is over heated.

But then who am I to judge?

Sorry Jamie, long week, didn't mean to "snap" as it were.

No worries Nic...no offence taken. ;)

So you might as well do the mods - egr bypass and decat!
No one will know, no one will ever check.

If you've tuned the engine, then they are probably beneficial.

As Jamie says, if there is less visible smoke and less fuel is used that tells me the (important) emssions are reduced.

Ron

Ps
Some BMW owners believe that BMW have spent so much money developing their cars that they are perfect and can't possibly be improved upon. Yet its funny how others are proving them wrong....
I suppose if the egr bypass was £500 they might be more inclined to believe it worked!

[QUOTE=Jamie-Biker in a suit;115781]
.I just think the thread is over heated.

QUOTE]

AArgh more global warming...

R

(by the way, I also agree the EGR bypass DOES do something that can be qualitatively felt too!) But surely the point re: the above is that BMW have a different set of legal and environmental responsibilities that they, as manufacturers, must obey. We can bend the rules and can be more singleminded in selecting the factors we wish to play up on, if we so wish.
BMW could never market something like the EGR bypass.

Excuse me!, who is proving who wrong? I don't think a small group of so called enthusiasts (that's my polite name) is any fit state to even suggest that they are following the path of righteousness. Damn arrogance.

Colin

I thought it was whether an EGR bypass would blow up my engine.................





Oh, and it hasn't done, at least not yet

[QUOTE=Roverron;115797]LOL...Ill go and turn some light off then..:D

Like I said.....definately over heated.

:iagree::wot: I think we've established that it won't, not on our cars anyway, which is what the concern of the original post was all about.

Russ

I'm not sure who you are calling arrogant, but I hope its not me!
I'm sure you meant those BMW owners with their head in the sand.

For the record, I was refering to those BMW owners who have actually tried Dave's EGR bypass for themselves and found that it does do what he claims, which is what those of us on this forum have also found out for ourselves.

I've been through all the arguments for and against covered in this thread on a BWM forum some months ago. But in the end I realised I was flogging a dead horse due to the arrogance of a vocal few.

The silent majority of that forum's membership must have been bemused at the pig headed arrogance of a few of their community who were quite offensive in their comments. Yet none would actually try one for themselves, though the ring leader eventually had the temerity to ask for a 'free' one to 'evauate' when I challenged him to put up or shut up.

Ron


.

I've never heard of anyone on any forum blowing up as a direct result of a disabled egr system. The L series boys have been disabling theirs for years too and previously mentioned, Landrover TD5 egr bypasses have been in use for years.

As for turbos that do fail, these tend to be VNT types which do not have a wastegate to control & protect from excessive boost pressure. So my theory is that its surge / overboost spikes combined with poor servicing, and possibly deficiences in the oil supply that kills them.
(One particular Garret one used on the Freelander Td4, Renault DCi and some BMW's, a GT1749 I think, seems to be prone to failing, so maybe its just a troublesome model)

Ron

Ron, Sorry poor choice of words there.

What I meant by that was, whatever is happening to the other makes of cars shouldn't really concern us as 75/ZT owners.

I don't think that the EGR is responsible for these problems. I totally agree with you that there is more likely to be a flaw in the design, in the maintenance, servicing schedule or a combined effect that is causing them.

Russ

Sorry ColinW I have picked you up on this once already in a previous post but it looks like I was too subtle. Stop being rude to people. Your point of view is valid and welcome, as are those of us who have the egr bypass. Yes, we are enthusiasts, you might have thought of a title which you would prefer to use - you have made your opinion of us very clear already.....but it is just an opinion....Arrogance does not come into it, the fact that we are not conforming to your view of the world is one of the things that makes the world a better place..... we are free to disagree.....but we do not need to be insulting about it. :)

I am so pleased that it isn't just me who thinks this is the case.

I also tried to make that point earlier in the thread in a restrained manner but was completely ignored.

Well, I will say here, for the record, and in less subtle terms, that I agree wholeheartedly with you Zeb.

The thread does not benefit from such rudeness and it seems to me that the arrogance is being displayed by ColinW and nobody else.

I think the question is how many M47R engines have blown up at all regardless of the state of tune. The answer is not many at all - in fact does anyone know to one?

ANY engine can blow up regardless of being standard or not. It does appear however that these engines are in general very strong.

It all has to be put into perspective and the fact is that ANY tuning can increase the risk of a failure BUT the risk appears to be VERY small. For the total transformation of how the car drives I for one am happy to take the risk.

To Zeb & Raistlin

My, you are sensitive souls. I can assure you if I really was trying to be rude, I probably would be banned from this forum.

However, I get very iritated - as much as you do- when factual reports such as posted by Rincewind, are looked at with a completly different perspective to the truth. By which I mean, it was viewed by one or two, as supporting the disconnection of the EGR and it wasn't till I persisted in getting Rincewind to explain this, that it was eventually cleared up. One member did have the guts to admit he got it wrong.

Another thing, I offered, what I thought was a concession, to put our thinking caps on, and perhaps come up with some form of halfway house, where the environmentalists, and the bypass brigade, can each have a bit of the cake. Virtualy no response.

How many read the contents of the link I put up.? One to my knowledge. If others had actually read it, then you would have seen that the alteration of injection timing, to 12 deg BDC, had a dramatic effect on emmisions. That's why I suggested that anybody into re-mapping might like to have a go. I know that's asking a bit much, but at least it should have sparked debate.

I've got some ideas which I am exploring. Which, if I can find time, I will try & implement. Not for any commercial gain, just out of interest.

So you see, when people criticise, without offering anything in return, and the only goal they seem to have, is power at any cost, is there any wonder I get frustrated.

Colin

On the contrary, we just happen to be two members who decided to voice what many other members think (going by my PM inbox).

In addition, neither of us chose to drop to your level, merely trying to point out that you were not doing justice to your cause.

Why not just assume that your argument stands upon it's own merits and avoid the rudeness and sarcasm?

Rincewind is immensely respected by everybody around here. Paying lipservice to his posts is certainly not something that the vast majority of forum members are guilty of.

However, the data you speak of is homologation data required by the DoT for type approval and determining taxation classes of a new vehicle. It is not part of the MOT test for diesels so it does not come into the consideration of somebody wishing to replace the EGR valve with a goal of increased performance/less smoke in mind.

The point of this thread is whether bypassing the EGR valve will damage our engines. If you want to start a separate one about whether it will damage the environment, you are very welcome to do so.

I get frustrated with something every day but as I said above, the discussion is about whether or not fitting an EGR bypass will damage our engines. If any forum member wishes to replace his EGR purely for power gains and couldn't give a damn about the environmental impact, that is his/her business and nobody elses.

Colin, Yes I did appologise for my mis-interpretation on the second set of figures.
If fact as Rinceweed said himself he could see why, and I quote:
"Or perhaps I should have said (without managing to confuzz myslef) we bypass the EGR system in a number of ways so that it doesn't work full stop."

But in no way does that alter or discredit the points that I was making.
That these modifications are there to increase the torque of the engine which can improve economy. (It's got very little, or nothing to do with going faster.) The effect of which can only be a reduction of the overall total emmisions.
Yes I agreed that the levels of NOx would rise, but the level of particulates would fall . Which is backed up in the first couple of paragraphs in the link you posted.

I agree that it is possible to design an engine and it's systems to reduce both types of emmision, but as a realistic proposition ( both economically and practically) for our cars, that would be unlikely.

I would try the modifications yourself as listed, then you could perhaps comment on the effect that these have from a point of personal experiance rather than one of theory.

You would get most of your money back if you re-sold them should you find that they didn't work or meet your requirements.


Russ

Nobody is paying lipservice to Rincewinds report. It stands on it's own merit. Also we are all aware that those tests having nothing to do with the MOT. They demonstrate what the EGR system is doing to remove NOXious gases. If you or anybody else wish to ignore it, then that's your perogative. It clearly suits your argument if it is ignored. But sure as eggs are eggs, it will come. So then what?

What's the point. The 'Bypass brigade' wouldn't take part. Even one of our own moderators voiced this quite clearly- he couldn't care a damn. That's a sad thing in itself, in as much that it seems to have clouded judgment to the point that nobody is even considering the possibility the're other ways.

If you yourself have sufficient engineering knowledge, as I'm sure you have, then is it not possible to enter into some meaningful discussion about how to achieve both our aims?

Colin

Colin, I fear the only way to achieve power increase and reduce emmisions would be (dare I say it) to go and buy a more modern diesel...then there would be no owners club, no forum, no discussions and we would all be driving around in little chinese tin boxes partially built from metal that was stolen from our churches and schools.

Exactly.

Russ

P.S. I will be unavailable to comment for a few days , so don't think I'm ignoring anyone.

It makes no difference to my argument. Its not tested for in the MOT and even if it does become part of the test, it will not be retrospectively applicable so will have no impact on our cars.

I think its exceptionally narrow minded and incredibly arrogant to take the stand that the club members are so unintelligent that they have somehow been brainwashed by one person's opinion and views. Everybody makes their own decisions and so far as they don't break the law of the land, they must be respected. Democracy and freedom of speech in action.

I'm no engineer and my understanding of diesel engines and the M47R in particular has been self gained rather than taught. The EGR bypass tube available to us is of a basic design but it does its job perfectly.

The one way I can see to improve it would require a remap to the ECU to recalibrate the values for total volume and flow rate of the intake air ducting. You could then retain the EGR system but increase the diameter of the EGR valve and the intake manifold itself by an amount equal to or greater than the volume of the EGR valve piston. This would maintain the re-burn of noxious gasses whilst continuing to increase the volume of induced air.

In my opinion this approach would be prohibitively expensive due to the small market for this type of device but it would definitely increase engine performance whilst maintaining lower emissions.

You're absolutely right!
However, there's a lot of us out there, who are sort of lumbered with what we've got.
The M47R engine is basical quite good, suffering as it does by the BMW constraints. I do understand, despite what some might say, that if some of it's latent power can be released (for those that want it), then yes, that is a good thing.

My only reservation is it should'nt be at any cost

So, getting back to the original discussion - I think there should be a poll, to see how many people would:-

A/ Have a bypass operation
B/ Leave well alone
C/ Happy with bypass
D/ Would disable EGR
E/ Change back from bypass or disabled EGR
F/ Unsure

So how about it?

Colin

Sounds like a good idea - especially if people would explain their reasoning. Then those of us for whom mechanical engineering is wizardry, would have a range of ideas to directly compare.

I think it should be a completely separate thread to this one though.

Who is this Rinceweed character? He keeps popping up and making an appearance - does anyone know what he drives?? :sissy: ;)

Nic

Not everybody has read Pratchett I guess Nic ;)

There is a difference between being a 'sensitive soul' and expecting good manners from people.....the rest of your points are unrelated to your lack of them..;)


On a happier note, the thread itself is absolutely fascinating:)

I know, thought I'd lighten the mood a little (he he)

Presumably Rinceweed drives a weedy 110 version of the R75 :)

I have followed this thread, sometimes with amusement, and sometimes with despair.

Reading many of the comments by the more "environmentally enlightened" members does, however, make me a little angry.

The UK is becoming legislation crazy regarding environmental issues, be it vehicle emissions, home fire emissions, second-hand tobacco smoke, etc. etc. Yet we still suck up to our "friends" across the pond, who are probably the world's worst when it comes to protecting the environment, soon to be overtaken no doubt by the Chinese.

The effect of all of Europe's environmental legislation has the significance of a spot on a fleas compared to what these two countries are doing, so if some of you are really interested in protecting the environment, go and lobby your MP's to make noises where it counts, and leave the poor motorists alone.

One Jumbo jet taking off from London airport does more damage every day than all the guys on this forum who have modded their cars do in a year.

OK, that's my rant over.

Mick

I think that Rinceweed drives the worst car on the planet - the Vauxhall Vectra!!!!!!!!!!!!!!! :sad3:

Oo, I shudder at the thought!

In Response to Colin's Comment on a Mod's View to the Environment.
As I have mentioned on a separate relevant Thread, My views were not that of the Club and were of a Personal Nature, not that of a Mod/Club representative or Spokesperson.
As a Mod obviously I have to hold back at times, but the debate on "Green" issues or "A good Excuse for more Tax taking for a Con" by the Government is one which many people agree with.
Everyone is entitled to their Opinion, as long as is not put across rudely or to offend.
The reason for my delay in responding was because I was off on another 747 trip to the States (13th this year) and with also a 40K annual mileage etc I know my Carbon Footprint is massive, but also as Stated thats up to me and I Pay for these things so I use them as I see fit for my Enjoyment/Work Requirements.
That may not be very Politically correct, but Thats me, if you want to save the Planet I am not going to complain about your efforts, it is after all at the moment allowed to have free Speech.
Go to India, China and America and tell them.
If the whole of the UK gave up all Emissions/Global Warming causes it wouldn't make one penny of Difference to the World as we are still one of the Smallest in % caused.
For that reason alone I will not join any Recycling, cutting down Power etc. A personal Choice.
I live right on the Coast and would be one of the First to suffer, and have Children and Grandchildren also, but Look after them by ensuring they get a Good Education, University and a well Paid Job so they can make their own decisions and pay for them.

out of interest, what do you tell your grandchildren re: the above?

I show them Where I go What I do and Why,
I have shown them both Programs and Films from both Points of View (plenty available in the US to back both Arguments)
I also show them that if the Biggest Polluters in the World did something it might make a noticeable difference.
It helped with the Fact that a Presentation at schools here shows that
the Removal of the Amazon Rain Forests causes more damage to the Ozone by its removal,
Than the Total output from Road Vehicles in Europe!
Food for thought, even I didn't know that.
Public Transport that is More Costly than running a Car, when you see any.
We have a Massive off Shore Wind Power Site, which can never pay for its Costs in its Lifetime and has yet to ever reach 50% of what they said it would do. (and One of the Country's Biggest).
Its forever breaking down or is Switched off for two different reasons.
1. To much wind above what they can Handle.
2. No wind at all so know Power.
Nuclear is the Only answer I and they Believe, I don't know if they have learnt that at School or not as its one area I have not touched with them.
They are then left to their own minds to make up,
but with the extra Tax Gimmick you would have a Hard Job convincing anyone,
as its Just a Rip off which is not used correctly when Raised.

Here our Councils who ask you to separate your Rubbish (Recycle?) only have a 45% take up and as they are then putting it into Landfill (a Joke in its self)!
because they have "mountains" of Tins, Paper, Card etc which is not wanted anywhere because firms are overrun with Recycled Waste and are still purchasing "New" as it has now become Cheaper.
Yes I know the World has gone nuts.

YES I KNOW SHOULD START A NEW THREAD AGAIN. :D

Is there not a very large element of hypocrisy when motorists start voicing their 'green' views?
If a motorist was really concerned about the environment, would he/she not drive the most compact, fuel efficient vehicle that they they could.
The Rover 75 & ZT are large heavy cars, the diesel engine installation dates back probably 10years, the tourers and automatic models are significantly thirstier and even more polluting. But let's face it we have an emotional attachment to our cars which overrides everything else.

My conscience is clear on the 'green' issues of tuning because if I didn't / couldn't tune my engine (something I've been doing for 30odd years) I'd just buy a more powerful, off the shelf, but probably, equally polluting vehicle.

I also don't accept that a functioning egr system is necessary to ensure reliablility of the engine or turbo. It beggars belief that when an egr system malfunctions due to maf issues or is disabled by the owner, damage will result.
I have seen no evidence that this happens on any engine and certainly no L series or M47R engine has suffered.

If you believe the scaremongering, then leave the egr system alone. .

Ron

Sorry Rincewind, owe you another piece of humble pie.:o:o:o:o:o:o
Tried so hard not to make the same mistake, then ended up doing it all over again!!!!!!:banghead:

Appologies,

Russ

Still trying to get my egr bypass. No respones from Dave at all??? Anyone got one they dont want?

He's working away and has had family illness to contend with so hopefully you will get a reply in the New Year.

Ron

I know he will sort later, he is a Bit Preoccupied at the Moment sad to say.
So please be Patient. :)

Sorry Ron, see you have already responded, Must read all messages first! :D

Well I know which Flow path I would choose if my body was made of Air molecules.
I'd say this is a 30% restriction, but hey ho you would think the EGR designers would account for the engines air demand when full power required.

Left:............................................. ..........Right
choked EGR 40k miles.................................EGR Bypass from Dave (has he emigrated?)

http://www.the75andztclub.co.uk/foru...e47005bdc3.jpg

I think he's back but he's not talking to me (nor even dare email it seems) since he left everyone, me included, wondering what was going on.

Apparently, he has had family problems (her in doors has thrown him out doors) and a new job which involves overseas travel.

Hopefully he'll respond if anyone wants to contact him

[email protected]

I'm really sorry he's got problems but it would have been sensible to simply say he was going to be away for a couple of months and put an autoresponder message on his email rather than just 'disappear'.

Ron

Always sad to hear these things.
It's always a life balance between spending time with your Passion and the wife!!!
Should be the other way round I know.
Glad I bought 3 bypasses from him when I did (only one left now & it's spoken for)

I notice that Dave is now selling the bypasses on e-bay again:
http://cgi.ebay.co.uk/MG-Rover-75-ZT...QQcmdZViewItem

Just in case anybodys after one.

Russ:D

Looks like he's back in action then!

Ron

This doesn't add anything to the debate as to whether the bypass damages your engine and/or environment, or not, but I just thought I'd say it anyway...

My 2002 CDT, with 166,000 miles on the clock, recently passed its MOT and the tester said that smoke was negligible, really really low. This is despite having a Rover Ron Synergy box set on 10, a setting most likely to be smoky. I wondered why this might be, then recalled that I did the EGR bypass some months ago. I presume it's that which has brought the smoke down so low.

As to NOx emissions, I vaguely recall reading some years ago that EGR valves reduce them in young engines but either don't so much, or are no longer necessary, in older engines. Is this so?

Tend to agree with your sentiments Johhny, and to date there is no evidence on this forum that bypasses have done any damage.

Different scenario altogether if EGR Valve left fitted (unserviced) for life of engine:
A fully stuck open EGR however in my opinion wouldcause some long term damage in that a constant flow of 15% hot exhaust gases going through the inlet would coke it right up to the point where the inlet would "close up" with carbon and suffocate the engine.

with respect for the item and not wanting to scaremonger (I've had one and its great), surely we know that it may be 30,000 miles before any negative feedback arises? I too had massive smoke reduction at MOT time. But the key bit for discussion surely is the raised temperature in the head over long hours of motorway cruising?
I naively equate the standard EGR as something which effectively decreases the capacity of the engine when power is not needed, through its introducing inert gas (i.e. it just helps fill the chamber but doesnt combust) at these low demand times. Less burnable air means less fuel needed so computer supplies less. So its a double whammy - fuel saved and NOx reduce as temperature is kept lower as the combustion going on is proportionately lower for the size of the space.
Is there any sound engineering precedent for equating the effect of the greater stress put on the combustion chambers in these periods of low-stress running!? (forgetting environmental and fuel consumption factors which are irrelevant for this discussion - I'm interested in longevity for a car I might have from 80k to 180k or longer)

Ron mentioned grinding out some of the obstruction in the standard EGR - and I've done this yesterday with removal of the jagged 1mm-high 'join' between the alloy tubes, around the inner circumference. I'm now interested in which bits of the brass and stainless steel are reduceable. Has any one got a duff one they can attack to see which bits are hollow and which bits might be capable of bit of reduction....?

I toyed with this when I cleaned my EGR but "bottled it". I, too, wondered how much was removeable but more-so, what cavities would be left. Not wanting to start this heated debate going again, but surely if there were holes/cavities left in the wall of the "doctored" EGR then that would be almost as disruptive to the airflow as the obstructions being there in the first place? That's basically why I bottled out of the grinding and cuttinghttp://www.the75andztclub.co.uk/foru...ons/icon11.gif.
And then there's the bypass being sold for people not as tight-fisted as me. I do like to have a go myself!!

the alloy casting (existing EGR) is made up of two tubes end to end that come together around the perpendicular valving sections. They aren't very neatly joined but its fairly obvious that it is all solid and easily gas flowed to gain a few percent more cross-sectional area. On a crude time:benefit analysis of narrowing the walls of the alloy, it doesnt appear to be worth bothering.

Its the small brass bit that seems 'ripe for the picking', if one know what it did or didnt do!

There was lots of talk about egr valves when I owned my Mitsubishi Pajero, some people recommended using a blanking plate others did'nt, I did purchased a blanking plate for the egr valve but never used it, instead I went onto ebay and purchased a valve cleaning kit.

Process took about 3 hours soaking the valve in different chemicals and oils etc, when the final process was finished the valve looked like brand new, cannot say whether or not it made my truck perform better but the amount of gunk and crud that came out of the valve must have been detrimental to the performance of the engine in some way I would think.

Well I'm driving many Hours a Day, today a return home trip all Motorway of 300 odd miles and did the same to work this morning getting there and never had any ill effects (except on my wallet!)
I've now done about 23000 miles with it with nothing bad to report.

They've been fitted to Landrover TD5s for years with no ill effects.

I'm sorry, but I still cannot see how there can possibly any higher a thermal stress on the engine under the conditions when the egr system is in operation which is light load, part throttle only.
The flame front may be hotter as there is more O2 present but the relatively minimal amount of fuel present means the 'size' of the flame is small.

If pistons were melting and valves burning under these conditions how would they cope under full load when the turbo is forcing in even more undluted air in and the egr system is not operating?

Ron

Also the HOT gasses from the turbo can't be that hot when they go through the EGR valve and then into the PLASTIC inlet manifold if I'm not mistaken!! This assembly would surely melt before before valves or pistons;)

I really cannot understand, despite all that has been discussed on this thread, that you still do not understand, that it is the instaneous combustion temperatures that are so destructive, and NOT the average exhaust temperature. Also the small amount of exhaust gas which is injected by the EGR, is hardly going to raise the temperature of the incoming air.

So please, I don't mind you singing the praises of the EGR bypass, but please do it with some technical credability.

Colin

Colin you can't say that without eveidence to back up your assertion.

Where is your proof of this destructiveness?

As I said, the instantaneous flame front temp may be hotter with no exhaust gas recirculation but the flame itself is not as 'large' or 'aggressive' (fierce) on light load due to the minimal amount of fuel injected.

Put simply, Colin, you conveniently overlook then fact that it requires fuel as well as oxygen to produce heat and there is just not enough fuel for damaging conditons to exist.

When the fuel is turned up, the egr system is switched off so why don't engines suffer damage if driven at 85-90mph when the load is moderate and the egr system is not functioning? (or when towing at 50mph for mile after mile, or into a head wind etc etc)

You are flogging a dead horse trying to convince me that common sense and gut instinct that comes from 30years of tuning is wrong! So there!

Ron

i did over 35k of M6 driving to n from glasgow in my 600LDi without any problems , it had one of ron`s tuning boxes and the EGR blanked

Colin, I'm afraid, is confusing temperature with energy.
This is akin to confusing volts with watts and an elementary mistake.

We all know high voltage isn't lethal or damaging if the current and hence power is very low. (Tasers, static, cattle fence, spark plug HT leads etc)
The tiny amout of power is easily dissipated over the body without causing damage.

Its the same in the combustion chamber. The flame front temperature may be higher but the heat energy is small due to the minimal fuel quantity injected. The combustion chamber walls and piston can easily dissipate the small amount of extra energy. If they couoldn't the engine would go into meltdown under full throttle when not only is there 5 times more fuel injected, but no exhaust gas being added.

Ron

I've also graduated to a 75 from a 600 diesel, and I too disabled the EGR valve on my 600. In my case it was because it turned out to be the cause of a long-standing running trouble, where whenever I went over 80 mph or so, suddenly it would feel as if there was a dab on the brakes, the check engine light would come on and no further acceleration was possible. I spent ages (and a fortune) trying to diagnose the problem, particularly as it was somewhat intermittent, but after disabling the EGR valve the problem never came back, so I concluded that that was the culprit.

Out of curiosity, how effective was Ron's tuning box for the 600? I had had a Superchips rechip long before Ron came out with his device, as well as a much enhanced intercooler (courtesy of Allard), and the car really flew.

On a Trip to Germany I was doing speeds of up to 130MPH Indicted for many, many miles and as previously stated no ill effects, Still clears MOT fine, and no other Problems on my Regular services. I have done over 80 odd thousand miles from new in this car, it is driven very hard and only just 3 Years old.
I more than some have many Mods including a Custom, Remap A Synergy Box, Ron's Spring Mod and MK2 Air Intake Mod etc.
I have seen nothing wrong caused by any of this and only thing left now is De-cat when mine dies!
Rolling Road Tests show 170BHP so where is any evidence to show this Damage, Overheating or Anything Else?
I think Ti Rich has gone slightly Further than me, also with no Problems, and a Lot of cars never even had the SGR Valve if I'm correct.
It works, Its your Choice if you use it, and at the End of the Day unless you can find concrete written Poof of the Problems you State, then I suggest you don't do it to your Car and don't talk about unproven thoughts of your own!

If you can Indeed prove your Comments and Statements then please share and display with us, I submit my car for any Tests to disprove any damage caused, and My mileage Logs will back up my Driving Times and locations.