How to test the MAFs yourself and How MAFs work - Page 36

V8Freak · 15th September 2008, 14:56

The right MAF on my engine is dead (0.03V readings) . The other seems fine . Do you think it is ok to change only the MAF that is dead or do I have to change both MAFs? And another question , for example if a MAF is giving 80% readings and the other is new (100% ) the air-fuel mixture will be made for both banks after the low MAF readings or different for each bank?

MarkQC · 16th September 2008, 17:03

NO, ...just change both at the same time...

TMcNasty · 16th September 2008, 21:49

Quote:

Originally Posted by MarkQC

...just change both at the same time...

x2. V8Freak since both air intakes lead into a common area (plenum)...you won't have a 100% correct side and an 80% correct other side. It'll average out to a 90% correct air intake reading across all 8 cylinders.

The VW MAFS are cheap enough that it's a no brainer to swap them both.

V8Freak · 17th September 2008, 00:37

Quote:

Originally Posted by TMcNasty

x2. V8Freak since both air intakes lead into a common area (plenum)...you won't have a 100% correct side and an 80% correct other side. It'll average out to a 90% correct air intake reading across all 8 cylinders.

The VW MAFS are cheap enough that it's a no brainer to swap them both.

check this thread .. MAFs arrived from London Mike!

quote " I've tried and tested the VW Mafs from David S - sensor code: F00C2G2032
I've also tried and tested sensor code: F00C2G2027

Both alternative bosch sensor parts work in the M5
- F00C2G2027 excellent top end performance, poor low end + stalling issues
- F00C2G2032 very good cost effective compromise but I personally felt bottom end/mid range torque wasnt as strong. Not as smooth.

In the end I had to resort to going back to the orginals - I took a chance with Mike - and it has to be said - it was worth every penny. A noticable difference. Finally I've got a benchmark to compare the
other sensors against. Simply put the alternatives aren't as good. It is worth paying the extra for the correct sensor code: F00C2G2029. Mike this represents greatvalue and thanks for the great service. Hiighly recommend. "

I have tested also 062 from my other car - 525dA and the M5 was running ok .. with some mid range loss of torque.

It is very clear that the compatible 032, 062, 027 are not giving the same readings as 029.
I will go with what BMW specified for this engine - F00C2G2029.

As for the other question I have asked , if one MAF is reading 100% on the left and 80% on the right...

If the air passing through the MAF on one side is going to the bank on that side, I think the ECU will make proportional fuel-air mixture .. 100% and 80% . If the air is going into a common area , I think the ECU will make an average - 90% like you said.

So if one MAF is going bad , the bank on that side will not run leaner, but the whole engine. Is that correct?

What happens if we run with one good MAF connected and the other disconnected? In this situation what are the default MAF values - % of 100% working MAF ? Is the ECU using the same values for the dissconected side as those read from the other good side? Is the engine running richer or leaner? Will it adapt itself using lambda values?

rneedham1979 · 17th September 2008, 02:14

once the air enters the plenum its all a wash. the plenum isn't divided,

ryan

Quote:

Originally Posted by TMcNasty

x2. V8Freak since both air intakes lead into a common area (plenum)...you won't have a 100% correct side and an 80% correct other side. It'll average out to a 90% correct air intake reading across all 8 cylinders.

The VW MAFS are cheap enough that it's a no brainer to swap them both.

Apeman · 17th September 2008, 07:57

Quote:

Originally Posted by V8Freak

What happens if we run with one good MAF connected and the other disconnected? In this situation what are the default MAF values - % of 100% working MAF ? Is the ECU using the same values for the dissconected side as those read from the other good side? Is the engine running richer or leaner? Will it adapt itself using lambda values?

I haven't tried running with one side disconnected, but I did try with both sides disconnected. The engine definitely ran a lot richer, to the point where the engine did stutter at WOT. I checked the fuel flow and it actually seemed to be up something like 20%. The MAFs were recently changed by the way, so should have been in good working order. That being said, I'm currently getting something like 15% lower fuel flow compared to reference values.

Ted · 17th September 2008, 16:10

Just to confirm, is post #354 saying BMW MAFs are better than VW MAFs?

V8Freak · 17th September 2008, 16:35

Quote:

Originally Posted by Apeman

I haven't tried running with one side disconnected, but I did try with both sides disconnected. The engine definitely ran a lot richer, to the point where the engine did stutter at WOT. I checked the fuel flow and it actually seemed to be up something like 20%. The MAFs were recently changed by the way, so should have been in good working order. That being said, I'm currently getting something like 15% lower fuel flow compared to reference values.

I think running with ONE MAF DISSCONECTED OR WITH BOTH MAFS DISSC. enters the same ECU mode : ENGINE RUNNING 15-20% RICHER. Thank you for your reply. Keep you posted with my consumption data after receiving the 029 MAF and installing it

mubarak · 24th September 2008, 20:15

HI ALL:
i tried this last monday..i got 152 in 2nd gear...so i didnot try 3rd gear yet...what do you think..is that good reading

thanks......................................:byee5 5amg

Beetos · 11th October 2008, 05:37

Some data:

2nd gear on rev limiter
25DegC
around sea level
Normal brometric pressure ~1050

Peak reading 142l/h
3rd gear run 138l/h

Sounds about right?