MAF what symptoms would make you condemn...MAF..

[Kakaire]

the massive Airflow Meter. I am tracing a rough Idle/slight ingine vibration and idle hunting at startup from cold and in stop and go traffic.

I have read the archive for three months so far, but looks like I am not getting a fix. Background: Ma baby was in an accident early feb this yr messed up alot of stuff from front pushed all face to the motor. I managed to replace God knows how many expensive parts up to the windscreen. Now I am stuck with this rough idle and a stickly rev btn 1000-2000 rpm.

Baby won't rave smoothly until after 2000 rpm all she does is baa baa baa baa baa until rave metre hits 2000 something.

So far I my indy did.

A head job, replaced water pump, timing belt, afew roker arms and all valves, distributor cap and rotor, fuel filter, complete ignition lead set (Used), new plugs, fuel tank pressure regulator, radiator, condenser, bumber, bonet etc. He has also adjusted the MAF, but behavoir wont go away and becomes worse in stop and go traffic at end of the day all plugs are covered in carbon.

Someone please help as now I stongly want to replace the MAF with a new one though want to spent this money justifiably cos you know how much it costs.

Lastly in ma country I don't have a dealer and have very limited diagnostic resources.

thx.

[shogun]

Maybe this helps
http://shrubbery.student.utwente.nl/sean750/MAF_v12/MAFtroubleshooting.htm

[emw525E34]

Hi Kaka,

Firstly, in your M20 engine its called the AFM not a MAF. Its a different technology and not compatible directly without some serious modifications. AFM is air flow meter and its uses a vane type flap with a carbon resistive track to change the resistence.
MAF is used by M50 engines and above, it uses a hotfilm to measure "air mass" rather than air flow volume. Similar but different enough not to be compatible.

My sedan uses AFM. If you are very adventurous, you can open up the AFM and try to "clean" the carbon track and its copper slider contact. This is rather dangerous becuase a small mistake can break it. Best to find a used AFM and recondition it. This way, you always have a spare.
Mine ?. I switched to 535 AFM and hooked an Apexi SAFC2 to control it. It is difficult to do and "Very adventurous" in my younger days about 3 years ago. This way, my Apexi is just like having a dynamic chip tune with the buttons so I can control torque and fuel consumption levels the way I wanted. More power/torque more fuel it burns, less power and less fuel. Good Luck.

[Kakaire]

Maybe this helps
http://shrubbery.student.utwente.nl/sean750/MAF_v12/MAFtroubleshooting.htm

Shogun the link you gave me is wonderful, it talks about the same exact issues am having thanks so much. Right now am looking for a new AFM to have mine replaced and over the weekend I am gona try out the given trouble shooting idea.

Emw, man thanks for correcting and giving good ideas. bless..

[shogun]

o.k. AFM:
cleaning the AFM, look from item 9
http://paulaxford.com/bmw730i/index.htm

[uscharalph]

o.k. AFM:
cleaning the AFM, look from item 9
http://paulaxford.com/bmw730i/index.htm
Very informative, Shogun!

[Kakaire]

Thumbs up Shogun... looks like I am gona be busy over the weekend.

[8 POTS]

Think MAF is buggered! things look bad from what i've read.
Can somebody please give a opinion.
Could car drive normally with full performance, then just loose all power and refuse to do anything except idle eratically at the side of the road, only to recover fully and come alive again after few minutes?

Please tell me you think it's fuel pressure problem and not MAF.

[shogun]

I put my money on fuel pressure.
What about the fuel tank. If that happens, open the fuel lid/cap. If you hear hissing, then you got it.
Check the valve in the fuel return line.

[8 POTS]

Not tried the fuel tank to listen for hissing. But I hope u right. My opinion is that if it was the MAF it would not be 100% fine at times. It would be rough constantly? Car is with mechanic and he says he think it is MAF but not sure. I have doubt in his diagnostic capability. Should probably take it to BMW dealership but in my country it costs a fortune to have a BMW dealer touch your car once the maintenance plan has expired! (as i am sure it is in most others). I will have him check feul pressure valve, pump and filter etc just to make sure he does not replace expensive MAF if not needed. Thanks for response.

[SRR2]

Does your car have a camsaft position sensor? Because your symptoms sound like one of those that's on the way out. They're Hall-Effect sensors (basically an integrated circuit) and have a reputation for going intermittent and failing. Lots of E39 owners carry a spare in the trunk -- that's how bad they are.