? Duff MAF - The Unofficial BMW M5 Messageboard (m5board.com)

BenS · 13th October 2009, 22:52

Dear All,

My old M5 has just failed it's MOT due to excessive emmissions and running rich. My mechanic has changed the O2 sensor, but it has made no difference. Apparently he does not think it is the MAF. Come to think of it, the old girl has sometimes been a bit rough on cold mornings and even more thirsty than usual............ (the car that is.)

What do you think? Sounds like failing MAF to me.

Thanks,

Ben.

davidoli · 14th October 2009, 01:38

The MAF would be a definite suspect Ben , assuming that all of your coil packs and spark plugs are functional .

Have you pulled a plug and checked the colour ?

I may have a MAF if you decide to go that route .

D

BenS · 14th October 2009, 10:48

Thanks for your reply. Have not checked plugs myself, as the car is with my local indepenent specialist. He says that he does not think its the MAF but I am not sure how he has tested it.
Thanks for offering to help out. I will let you know we get on.

Ben

Sub8 · 14th October 2009, 15:07

Coolant temp sensor?

BenS · 15th October 2009, 00:06

Thanks for the suggestions. My mechanic now thinks it is a "relay" and has ordered the part from Germany. Says he is 99% sure the MAF is OK.

Watch this space...........

Ben

davidoli · 15th October 2009, 09:48

Fingers crossed Ben .

Was it a fuel pump relay ?

D

BenS · 19th October 2009, 23:44

Thanks everyone. It was a relay for the O2 sensor. It is all fixed and MOT passed!

Have just spent £2300 getting the car ship shape including fitting KW2 suspension. By the way, the KW seems fantastic. Not had a chance to fully test yet, but on a quick test drive it was great. I will post later when I have lived with it for a while.

Ben

davidoli · 20th October 2009, 00:57

Fantastic news Ben ........ Thanks for the update ...... I love a happy ending !

D

AfricaOffroad · 20th October 2009, 15:30

On a similar theme, have any of you guys cleaned the MAF unit using one of these aerosol can products?
Mine is not giving any trouble, but I'm wondering if a spray cleaning wont sharpen things up a bit?

Robinson · 20th October 2009, 15:47

Quote:

Originally Posted by AfricaOffroad

On a similar theme, have any of you guys cleaned the MAF unit using one of these aerosol can products?
Mine is not giving any trouble, but I'm wondering if a spray cleaning wont sharpen things up a bit?

I did it, not in the M5 but in a SEAT Alhambra with VAG TDI engine. This engine was rather lazy lately but after the treatement it recovered the punch that I remembered it once had. I can imagine that cleaning the MAF wire will work ONLY if it is dirty and the dirtyness is soft enough as to be removed by the solvent. There are cases with a deteriorated wire or internal electronic fail that need a diferent treatement.