Re: M3 stumbling/etc.

["Brad Franklin" <bbb@xxxxxxxxxxxxxx>]

My 97 M3 also does it, but it is not that big of a deal. If you just sit
there and let it idle for 20-30 seconds, you'll notice it will hit a point
where it will instantly clear up. The rough idle probably has something to
do with the ECU programming. I'm no expert on ECU operation (so correct me
if I'm wrong on this), but I believe the ECU starts up in an open-loop idle
mode when you start the car cold. This is because the O2 sensor needs to
warm up to give feed back to the ECU for ''closed-loop" mode. The open-loop
idle mode must not be calibrated well. Perhaps it is programmed to idle
lean, which may heat the O2 sensor faster. Who knows, but the idle problem
with my car hasn't been that big of a problem. Just let it idle for a few
seconds, or just deal with a couple bogs when you pull out, and then it
clears up. Also try turning on the A/C. It boosts the idle a bit and may
help avoid bogging if you're in a hurry to get going. Hope this helps!

Brad Franklin

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