Hesitations at acceleration

[Jim Lepage]

My M50TU has some hesitations (flat spots) at acceleration. It's happening when I start from idle to redline. If I start accelerating at high RPM it's not doing it.

What could do that:

-bad vanos unit ?
-bad O2 sensor ?
-bad crank sensor ?
-bad cam sensor ?

[Charlie]

MAF sensor. They tend to take a shit.

-Charlie

[omar85]

MAF sensor. They tend to take a shit.

-Charlie

what he said. read the codes if you can.

also check simple things like your spark plugs.

[Jim Lepage]

what he said. read the codes if you can.

also check simple things like your spark plugs.

Spark plugs and fuel filter are new. I'll check for the codes.

EDIT: I'll try to clean the MAF ( http://forum.e46fanatics.com/showthread.php?t=335561 ) and search for cracked hoses (vacuum leak).

[Jim Lepage]

I cleaned the MAF with caution with contact cleaner and it's now running very rough (vibrations) at idle and from idle to 2000 rpm. I don't see a big difference if the MAF is plugged or not and it's also smelling very bad.

Do I need a new MAF ?

[rThor432]

^^If there isnt a big difference between plugged in and unplugged, then it is very likely that your MAF is bad.

[e30s52]

Get a new one or test with a know good one.

[Jim Lepage]

Ok thanks for helping.

[e30s52]

You can try back probing it to to see if the voltage is in specs.

[BimmerTim]

If you need a MAF, I have a known working one that I could ship to you.

If you are interested, PM me.

[Jim Lepage]

If you need a MAF, I have a known working one that I could ship to you.

If you are interested, PM me.

PM'ed...

[Jim Lepage]

I'm at work and just received a MAF I found in a local scrapyard. My concern is the guy sent me a M52 MAF (Siemens 1 703 275). Will it work on my M50 ?

[e30s52]

I'm at work and just received a MAF I found in a local scrapyard. My concern is the guy sent me a M52 MAF (Siemens 1 703 275). Will it work on my M50 ?

The m52 maf will be obd2 I think. I dont think it will work. Try realoem and compare part numbers.