Failed MOT Today - Emissions

[johnbe60]

Hope someone can help...
Annual MOT today...
Failed on a couple of items...
One they couldn't fix was high emissions...
I have a 2.0 CDT...
Love this car...
They said it just needed a fuel additive and it should pass...
Told them to go ahead and do what was required...
They put in fuel additive and drove it on dual carriageway for 15mins...
It failed again and emissions went up from 3.7 to 5.0...
They said the engine was overheating and fan not coming on...
Don' remember having that before....
Anyone got any ideas to reduce emissions...
Also unplugged the MAF sensor a year ago...
All the best :}

[David Lawrence]

Hope someone can help...
Annual MOT today...
Failed on a couple of items...
One they couldn't fix was high emissions...
I have a 2.0 CDT...
Love this car...
They said it just needed a fuel additive and it should pass...
Told them to go ahead and do what was required...
They put in fuel additive and drove it on dual carriageway for 15mins...
It failed again and emissions went up from 3.7 to 5.0...
They said the engine was overheating and fan not coming on...
Don' remember having that before....
Anyone got any ideas to reduce emissions...
Also unplugged the MAF sensor a year ago...
All the best :}

Basic point but can you actually see the smoke by eye yourself?

If you can then the smoke is probably too high as usually they are pretty clean.

My usual routine before an mot is to use shell diesel for at least a tankful before the mot (as it happens i now use only shell fuel all the time anyway). If you are filling up at morrisons or similar then that wont be helping. Worth checking if your air filter is clean as well.

I then get the engine hot, on a brisk motorway run, then drive the last couple of miles to the station in high revs to blow out any soot from the pipe.

Never had it measure any higher than 0.8 on the print out they give you. It is usually lower than that though.

A couple of things about what they report to you sound a bit questionable. Never heard of a cdt overheating either. overheating? Fan doesnt come on? Hmm. I dont think my fan has ever come on because the engine was hot enough. Only time it does come on is when i run the a/c.

If you can see smoke yourself then fair enough, you need to investigate, but if you cant see smoke, go for a test somewhere else.

[Mike24]

I may be mistaken, but doesn't unpluggingthe MAF result in overfuelling and consequently higher emissions? Did you unplug the MAF before or after the last MOT?

[johnbe60]

Basic point but can you actually see the smoke by eye yourself?

If you can then the smoke is probably too high as usually they are pretty clean.

My usual routine before an mot is to use shell diesel for at least a tankful before the mot (as it happens i now use only shell fuel all the time anyway). If you are filling up at morrisons or similar then that wont be helping. Worth checking if your air filter is clean as well.

I then get the engine hot, on a brisk motorway run, then drive the last couple of miles to the station in high revs to blow out any soot from the pipe.

Never had it measure any higher than 0.8 on the print out they give you. It is usually lower than that though.

A couple of things about what they report to you sound a bit questionable. Never heard of a cdt overheating either. overheating? Fan doesnt come on? Hmm. I dont think my fan has ever come on because the engine was hot enough. Only time it does come on is when i run the a/c.

If you can see smoke yourself then fair enough, you need to investigate, but if you cant see smoke, go for a test somewhere else.
Thanks...
I can't see smoke and normally use Esso or Asda for diesel...
Would putting MAF sensor back improve it???
Took MAF sensor off as stalling when pulling away from roundabouts/lights...
John

[MrDoodles]

Sadly it sounds like you'll actually have to fork out on a new MAF! ;)

A word of warning though, don't be tempted to get a cheap Chinese one off eBay, as you may as well go into the back garden and set fire to the money you were going to use to buy one with! ;)

ONLY go original Bosch, which I'm sure that fitting and followed by a "Italian de-coke" will sort your emission problems! ;)

[Mike24]

I am currently awaiting delivery of a new MAF from the Mafshop. It's for a series 5 BMW and will not fit as a complete unit ,but the insert can be fitted into the existing body. This reduces the price by about £50 but voids the warranty. If you decide to take this option it can be found here
http://www.maf-shop.com/product_info.php/info/p57_MAF-Air-Mass-Flow-Meter-Bosch-BMW-0280217533-13621433566.html

[daznkel]

Might also be worth changing the PCV filter, if not done already. Only a few quid from DMGRS or the bay. :D

[johnbe60]

After much discussion and mis direction by Kwik-Fit I followed what was said on here and then went to a Garage (recommended) and passed within the hour...
Seems different styles of doing the test....Grrrr...
Won't be going to Kwik-Fit again....
Thanks everyone for your support....
Lesson learned is to have a service including cleaning injectors, replacing Air, Oil and fuel filter and giving it a hard run down the motorway prior to MOT...
Also using good diesel (Shell V-Power Nitro+)....
:duh::duh::}

[Darcydog]

Interesting thread.

Not at all surprised at the muppetry you experienced at Kwik Fit.

A friend with a Land Rover had problems with this lot - they constantly failed his LR because they were putting in the year as for the "Prefix" lettering when his LR was circa 20 year older and had the Letter as the "Suffix" of the Registration.

He said trying to make them understand was like talking to the mentally retarded.

[Darcydog]

Also using good diesel (Shell V-Power Nitro+)....


After being highly sceptical of these "super" fuels - I am now a convert. Have been filling up on and off with Shell V-Power and did notice quieter running, and more smooth running. In particular the diesel "shimmy" when you turn the engine off is not noticeable at all on V-Power. But it is just noticible now on this Sainsbury's stuff.

It was never as bad as on my sons 1.9 Astra and that car is just three years old! - and he put me on to V-Power as his car club rated it highly

Have filled up last two tankfulls with Sainsbury's fuel because it was "there" and quite cheap.

Boy do i notice the difference.

She will be having a tankful of V-Power very soon.

[bubs]

I didn't think the emissions were measured on a diesel for the MOT, just thought they went by smoke level

[DMGRS]

That was my understanding too - just smoke level (and of course the visual cat check).

[Little-George]

Shell diesel was mentioned, brilliant stuff wont use anything else, with a teaspoon of 2 stroke oil to a full tank. ( controversial that one is) but works for me every time.