MAF mod - Page 2

Jules · 19th September 2012, 22:40

I don't believe 60MPG with MAF disconnected for one minute!
It will be overfueling at certain rev/engine loads and underfueling at other loads.

MAF's are not there for fun.

We get 47.5 MPG pretty regular from our ZT 131. (good Bosch)
As an experiment with no MAF it dropped to 30 ish with irregular mapping.

Mike Noc · 19th September 2012, 22:47

Quote:

Originally Posted by Mark2000cc

I would love a definitive answer to this, does anyone know for a fact that unplugging the maf causes damage?

I don't know the definitive answer, but if there was any chance of engine damage in the event of MAF failure the safe option would be to shut the engine down.

As the designers added a back up map if the MAF fails then I'd take it as read that the engine can run quite safely in this mode.

Also there is no danger of a diesel engine being damaged by running too lean so the MAF is there more for smoke limitation and of course economy.

Mike

BigRuss · 19th September 2012, 23:07

I did post up some findings about running with the maf disconnected a while ago, the damage will only be to your wallet, as the back up settings are too rich, performance will also be affected.

The maf is there to give the right fuel air mix, without it connected or replaced with a maf more suited to another vehicle you cannot expect it to give the same as a in spec original Bosch maf.

Russ

Unclefista · 19th September 2012, 23:48

Quote:

Originally Posted by Jules

I don't believe 60MPG with MAF disconnected for one minute!
It will be overfueling at certain rev/engine loads and underfueling at other loads.

MAF's are not there for fun.

We get 47.5 MPG pretty regular from our ZT 131. (good Bosch)
As an experiment with no MAF it dropped to 30 ish with irregular mapping.

56.7 or .9 brim to brim from home to Manchester airport and back last week (dash said 60, which is why i refilled to check) thanks in no small part to the 50mph limit on the M62

If it was overfuelling to the extent you've seen surely it would be smoking even slightly ? Absolutely no smoke from mine that i can see, not even any deposits on the bumper.

I'll be buying a replacement as soon as funds allow, it's been low on my priorities list, but now the other jobs are done, it's next.
When I do, I'll check the mpg, I do the airport run regularly.

Mike Noc · 20th September 2012, 07:09

Quote:

Originally Posted by Unclefista

56.7 or .9 brim to brim from home to Manchester airport and back last week (dash said 60, which is why i refilled to check) thanks in no small part to the 50mph limit on the M62

If it was overfuelling to the extent you've seen surely it would be smoking even slightly ? Absolutely no smoke from mine that i can see, not even any deposits on the bumper.

I think it makes sense if you drive with an extremely light right foot then you can get good mpg even with the MAF disconnected.

The diesels always draw a full charge of air into the cylinders, there is no throttling, so there is plenty of air available for combustion as long as you keep the fuel injected to a minimum.

Agree if you drive normally then at times you will be overfuelling the engine with the MAF disconnected, but drive very lightly and won't there always be plenty of excess air, no smoke and good mpg?

Mike

Singvogel · 20th September 2012, 09:41

Quote:

Originally Posted by Mark2000cc

I would love a definitive answer to this, does anyone know for a fact that unplugging the maf causes damage?

In my post I was thinking more about damage to the wallet rather than the engine.

I am astounded at the reported mpg figures without a MAF.

I too would like to know what permanent damage to the engine (if any) could be caused.

Singvogel.

paddyflan · 20th September 2012, 09:54

Apologies if I seem to be hijacking this thread but thought my question fitted the subject.

I have fitted a MAF compensator (£40 ebay) rather than replacing my not so efficient Bosch MAF . Now getting 55-57 mpg (as indicated on the instrument cluster) on a long journey with greatly improved lower down torque. Is it ok to run with that fitted without having any detrimental effect to the engine. Also do I need to disconnect this prior to an MOT?

Paddy

Quote:

Originally Posted by Singvogel

Pinebob is right.

Your car is now performing on the default settings, which give better results than the clapped out MAF that you had connected.

With a new MAF it should be even better.

Unplugging the MAF to see if it runs better with it disconnected is a standard test for an 'out of spec' MAF.

It sounds like you have never experienced an 'in-spec' MAF.

Not a good idea to run too long without a MAF - it could cause serious damage to your wallet!

Singvogel.

Singvogel · 20th September 2012, 10:22

Quote:

Originally Posted by paddyflan

Apologies if I seem to be hijacking this thread but thought my question fitted the subject.

I have fitted a MAF compensator (£40 ebay) rather than replacing my not so efficient Bosch MAF . Now getting 55-57 mpg (as indicated on the instrument cluster) on a long journey with greatly improved lower down torque. Is it ok to run with that fitted without having any detrimental effect to the engine. Also do I need to disconnect this prior to an MOT?

Paddy

Hi Paddy,

Should be no problem - all of us who are running the Synergy kits have compensators - either for the original Bosch or the Pierburg MAF, which only works with a compensator.

You certainly don't need to disconnect it for an MOT - it probably helps to reduce the smoke - which is the only emissions test a diesel has.

Singvogel.

COLVERT · 20th September 2012, 10:54

After reading all the above posts it would seem that the MAF is a refinement to an already efficient engine which can run quite happily without it.

A slight but useful addition to economy.

A bit like the double fuel injection cycle which also helps towards better economy by optimising fuel burn.

I join the others in thinking that no harm will come to the engine, just damage to your wallet.

Colvert.

COLVERT · 20th September 2012, 11:10

Quote:

Originally Posted by boofs

With the MAF disconnected the perfomance is same if not better and the fuel mpg is looking the best it has been,
NO WARNING LIGHT SHOWS OR CAN BE DISPLAYED ( there is not any engine warning light that I can see only airbag, ABS etc ),
Best mod by far i have done since owning the car from new,
I wish I had done it years ago I would be pounds in pocket on fuel saving etc,
I strongly recommend this for any one with the same car as me,

Top of the range Rover75 CDTI 131BHP 11/2003 Tourer Auto Conn SE,

Cheers.

I'm not disagreeing with anything you are saying about your car but using the seat of your pants as a method of assessing its performance is not really too scientific.

From various reports it seems that MAF's slowly loose their performance and thus make it difficult to assess, over a period of time, if they are working or not.

You say the fuel mpg is the best it's ever been but you might have had something else affecting performance other than the MAF.

What would help would be the full tank to full tank check to give you a really accurate number of M's per G.

19th September 2012, 22:40	#11
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	I don't believe 60MPG with MAF disconnected for one minute! It will be overfueling at certain rev/engine loads and underfueling at other loads. MAF's are not there for fun. We get 47.5 MPG pretty regular from our ZT 131. (good Bosch) As an experiment with no MAF it dropped to 30 ish with irregular mapping. __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

19th September 2012, 23:07	#13
BigRuss Premium Trader 75 CDT Tourer,2.5 Launch Saloon, Omipro MG/Rover (T4) Join Date: Jul 2007 Location: Liversedge, West Yorkshire Posts: 5,405 Thanks: 1,105 Thanked 1,340 Times in 661 Posts	I did post up some findings about running with the maf disconnected a while ago, the damage will only be to your wallet, as the back up settings are too rich, performance will also be affected. The maf is there to give the right fuel air mix, without it connected or replaced with a maf more suited to another vehicle you cannot expect it to give the same as a in spec original Bosch maf. Russ __________________ Replacement Key Service http://https://the75andztclub.co.uk/...d.php?t=244732 Full T4 Testbook diagnostics available. Diesel ECU repair and replacement. Options enabled or disabled as required. Diesel X-Power 135 and 160bhp, Rover 1.8T 150 to 160 MG 160 V6 to 177 upgrades available P.M. for details.

20th September 2012, 10:54	#19
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	After reading all the above posts it would seem that the MAF is a refinement to an already efficient engine which can run quite happily without it. A slight but useful addition to economy. A bit like the double fuel injection cycle which also helps towards better economy by optimising fuel burn. I join the others in thinking that no harm will come to the engine, just damage to your wallet. Colvert.