MAF mod - Page 3

hogweed · 20th September 2012, 12:48

Sadly I’m not a diesel expert – if this were a petrol engine, I’d say put the car in the garage, lock the door, and get a bicycle… however I can share my own experiences.

When I bought this car, it was clear that it was running very “flat” – I desperately wanted to get rid of the car I was driving, and the guy really wanted one of them, so we did a swap on terms which were advantageous to me…

Anyway, first thing I did was come on here, and got told that the MAF was likely faulty. You CAN buy just the Bosch sensor, and dig the faulty one out and replace it – so I did that. Much cheaper.

Just one thing to say – the performance was revolutionised. Not much wonder you're getting such unheard-of mpg; the ECU’s limp-home mode probably turns the turbo off.

COLVERT · 20th September 2012, 20:28

hogweed ( quote)

Not much wonder you're getting such unheard-of mpg; the ECU’s limp-home mode probably turns the turbo off.

And at the same time engages the pedals and chain drive.

binraider · 3rd October 2012, 22:19

I have been running my cdt (210k miles) for 6 months with the MAF disconnected. The original Bosch one must have been shot, because once i disconnected it the whole car suddenly awoke from slumber.

I dont drive the car that much as i have moved into the center of town, and work from home, but when i go to London every few weeks i make a note of the mpg and it is definitely similar to what it was before - 50 mpg. Mind you i drive like an old man.

I got the MOT done last week and it passed the emissions test without any problem.

I intend to get a synergy/Piersburg once i have done the clutch, but i am not particularly in a hurry.

Singvogel · 3rd October 2012, 22:30

Quote:

Originally Posted by binraider

I have been running my cdt (210k miles) for 6 months with the MAF disconnected. The original Bosch one must have been shot, because once i disconnected it the whole car suddenly awoke from slumber.

I dont drive the car that much as i have moved into the center of town, and work from home, but when i go to London every few weeks i make a note of the mpg and it is definitely similar to what it was before - 50 mpg. Mind you i drive like an old man.

I got the MOT done last week and it passed the emissions test without any problem.

I intend to get a synergy/Piersburg once i have done the clutch, but i am not particularly in a hurry.

50mpg is a remarkable achievement - well done.

If you fir a Synergy2a and a Pierburg you will probably get a bit less - but the car will be more lively and responsive.

Incidentally your car didn't pass an emissions test - because it didn't get one. It had a smoke test. There is no requirement for an emissions test on a diesel and no equipment at an MOT test centre designed to do such a test on a diesel anyway.

Signvogel.

Mike Noc · 3rd October 2012, 22:41

There seem to be a few posts on this thread that have gone missing between the 20th September and 3rd October.

Anyone know why?

Mike

Wayned · 3rd October 2012, 22:44

Quote:

Originally Posted by Mike Noc

There seem to be a few posts on this thread that have gone missing between the 20th September and 3rd October.
Mike

Yep forum crash, they lost a week: http://www.the75andztclub.co.uk/foru...d.php?t=125230

Mike Noc · 3rd October 2012, 22:48

Cheers Wayned. Don't usually visit the general forum.

Mike

vetrox · 4th October 2012, 18:21

I know I'm a bit late on this post but wanted to put my input as I have had a car die due to failed maf. (however this is a petrol car we're talking)

Maf is a vital part of the combustion cycle which tells the computer how much air is coming into the engine, the computer can then decide how much fuel is needed. Without the maf your car will revert to a "default"setting for the Air fuel mix. Some cars are quite happy with this but other cars (toyota celica for example) dont.

The long term damage will be from poor fuel mixture. If its too rich then you are generally safer (can still have problems from too rich mixture) but running a lean mixture (not enough fuel) will cause det/ping which if left unchecked will damage your pistons or cylinders or maybe something else in that area.

However diesels are a strange mystery to me and due to the lower temperatures and their natural lean-ness means you may well be ok and the extra fuel a diesel with no maf pumps in may well cause a performance gain!

Something like this

Oiled air filters have been known to cause maf sensors to fail.

Its normally best to have a working maf...its there for a reason :P most cars will run like a bag of **** without a maf. I have never known a car to run fine without one.

Some cars even have a MAF and a MAP sensor... could this possibly be the case with the diesel?

Theres plenty of info on the google about it.

Mike Noc · 4th October 2012, 20:06

Don't worry you can't damage a diesel engine by running it lean. The MAF isn't used in the same way as it is in a petrol engine, where the ECU needs to calculate the air/fuel ratio.

The CDT doesn't throttle incoming air so it always draws in a full charge. The fuel is injected and uses as much oxygen as it needs to combust. At idle, when little fuel is being injected, the air/fuel ratio can be on the wrong side of 100 to 1 and there is plenty of excess air.

So the MAF is used for smoke limitation, good power and economy with the ECU using the signal to calculate the available air for combustion to determine the maximum amount of fuel that can be injected. Anything less and the air/fuel ratio becomes pretty meaningless with a diesel engine.

Mike

Wayned · 4th October 2012, 23:06

Well the MAF has to be fitted for a reason, I would not be happy running mine with it disconnected.

3rd October 2012, 22:19	#23
binraider Regular poster 2002 Rover 75 CDT Saloon Join Date: Sep 2010 Location: Diss, Norfolk Posts: 66 Thanks: 76 Thanked 6 Times in 4 Posts	Running without MAF I have been running my cdt (210k miles) for 6 months with the MAF disconnected. The original Bosch one must have been shot, because once i disconnected it the whole car suddenly awoke from slumber. I dont drive the car that much as i have moved into the center of town, and work from home, but when i go to London every few weeks i make a note of the mpg and it is definitely similar to what it was before - 50 mpg. Mind you i drive like an old man. I got the MOT done last week and it passed the emissions test without any problem. I intend to get a synergy/Piersburg once i have done the clutch, but i am not particularly in a hurry.

4th October 2012, 20:06	#29
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Don't worry you can't damage a diesel engine by running it lean. The MAF isn't used in the same way as it is in a petrol engine, where the ECU needs to calculate the air/fuel ratio. The CDT doesn't throttle incoming air so it always draws in a full charge. The fuel is injected and uses as much oxygen as it needs to combust. At idle, when little fuel is being injected, the air/fuel ratio can be on the wrong side of 100 to 1 and there is plenty of excess air. So the MAF is used for smoke limitation, good power and economy with the ECU using the signal to calculate the available air for combustion to determine the maximum amount of fuel that can be injected. Anything less and the air/fuel ratio becomes pretty meaningless with a diesel engine. Mike Last edited by Mike Noc; 4th October 2012 at 20:20..

20th September 2012, 12:48	#21
hogweed I really should get out more....... Vauxhall Insignia CDTi; MG TF 135 Join Date: Jan 2010 Location: Norn Iron Posts: 2,958 Thanks: 942 Thanked 378 Times in 297 Posts	Sadly I’m not a diesel expert – if this were a petrol engine, I’d say put the car in the garage, lock the door, and get a bicycle… however I can share my own experiences. When I bought this car, it was clear that it was running very “flat” – I desperately wanted to get rid of the car I was driving, and the guy really wanted one of them, so we did a swap on terms which were advantageous to me… Anyway, first thing I did was come on here, and got told that the MAF was likely faulty. You CAN buy just the Bosch sensor, and dig the faulty one out and replace it – so I did that. Much cheaper. Just one thing to say – the performance was revolutionised. Not much wonder you're getting such unheard-of mpg; the ECU’s limp-home mode probably turns the turbo off.

20th September 2012, 20:28	#22
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	hogweed ( quote) Not much wonder you're getting such unheard-of mpg; the ECU’s limp-home mode probably turns the turbo off. And at the same time engages the pedals and chain drive.

3rd October 2012, 22:41	#25
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	There seem to be a few posts on this thread that have gone missing between the 20th September and 3rd October. Anyone know why? Mike

3rd October 2012, 22:48	#27
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Cheers Wayned. Don't usually visit the general forum. Mike

4th October 2012, 18:21	#28
vetrox Regular poster Not yet :( Join Date: Oct 2012 Location: Dover Posts: 37 Thanks: 0 Thanked 0 Times in 0 Posts	I know I'm a bit late on this post but wanted to put my input as I have had a car die due to failed maf. (however this is a petrol car we're talking) Maf is a vital part of the combustion cycle which tells the computer how much air is coming into the engine, the computer can then decide how much fuel is needed. Without the maf your car will revert to a "default"setting for the Air fuel mix. Some cars are quite happy with this but other cars (toyota celica for example) dont. The long term damage will be from poor fuel mixture. If its too rich then you are generally safer (can still have problems from too rich mixture) but running a lean mixture (not enough fuel) will cause det/ping which if left unchecked will damage your pistons or cylinders or maybe something else in that area. However diesels are a strange mystery to me and due to the lower temperatures and their natural lean-ness means you may well be ok and the extra fuel a diesel with no maf pumps in may well cause a performance gain! Something like this Oiled air filters have been known to cause maf sensors to fail. Its normally best to have a working maf...its there for a reason :P most cars will run like a bag of **** without a maf. I have never known a car to run fine without one. Some cars even have a MAF and a MAP sensor... could this possibly be the case with the diesel? Theres plenty of info on the google about it.

4th October 2012, 23:06	#30
Wayned Avid contributor Rover 75 Join Date: Sep 2012 Location: Somerset Posts: 214 Thanks: 0 Thanked 0 Times in 0 Posts	Well the MAF has to be fitted for a reason, I would not be happy running mine with it disconnected.