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DISCUSSION => Engine + Driveline => Topic started by: bigalrut on December 23, 2010, 06:05:45 PM

Title: Acceleration issues
Post by: bigalrut on December 23, 2010, 06:05:45 PM

Just experienced acceleration issues in my '91 318is.  The car idles and runs fine except it feels as though the engine is stumbling when I accelerate.  Anyone have any suggestions?

Title: Acceleration issues
Post by: dkbmxer002 on December 23, 2010, 07:05:22 PM

is it like it is "skipping" under full load? usually at speeds above 50? if so thats exactly what mine has been doing. it usually only does it once the car has gotten warm. i am assuming that it is the maf going bad or reading poorly.

Title: Acceleration issues
Post by: bigalrut on December 23, 2010, 07:22:01 PM

Yeah...have you had any luck troubleshooting the MAF?  Mine will also "skip" while I rev up the engine in neutral.

Title: Acceleration issues
Post by: Brian on December 24, 2010, 03:15:46 AM

Check for air leaks around all of the hoses on the inlet manifold side

Title: Acceleration issues
Post by: dkbmxer002 on December 24, 2010, 03:26:06 AM

nope. not much to do as far as i know except replace... but i am sure someone with more knowledge on here can give a better answer.

Title: Acceleration issues
Post by: DesktopDave on December 24, 2010, 07:08:03 AM

Do a stomp test, see if it has any codes stored.  It likely won't, but you never know.  Stumbling like that could be caused by an over-rich condition from a bad FPR or thermo sensor, a lean condition from the O2 or AFM, a flaky coil, etc.  The stomp test might give you a good point to start.

I'd grab my multi-meter & go through the usual culprits:
Cam & crank sensor resistance
Coolant temp sensor resistance both hot & cold
AFM resistance & AFM IAT sensor
O2 sensor volts & resistance IIRC.