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Discussion Starter · #1 ·
2001 E46 M3 Vert Manual

I have a minor low idle problem. It seems to happen sometimes when backing out of a parking space and changing from reverse to 1st. And when I am pulling into a parking space. It doesn't happen every time, and I can't easily recreate it.

These conditions seem to be present each time:
Clutch in
Foot off accelerator
Steering wheel turned
Slowly rolling
HVAC on

When this problem first started the engine would often die. Now I just get a very low rough idle. It seems to show about 500 rpm.

I did some research and tried the following things, which I attribute to now keeping the engine from dying.

Tested battery at Advance Auto Parts - It was fine
Cleaned Mass Air Flow Sensor MAFS
Replaced MAFS
Replaced Throttle position Sensor TPS
Cleaned air box including what I could reach of the yellow horns
Cleaned what I could reach of, without removing, the throttle bodies
Replaced air filter
Cleaned idle control valve
Replaced idle control valve
Attempted to reset the adaptive throttle settings using various sequences I found online. I don't know whether they reset them or not.

I know I could have likely taken it to the dealer and had them diagnose the problem from the get go, but that's not my style. I'd like to fix it myself, obviously. Even if it costs a little more money in the end. I haven't been able to figure out how to get the software to hook my computer up to the car yet, and I don't have any friends that can.

I'm leaning towards the alternator. Maybe I should take it out and have it tested. Any other ideas?

I could also give up and take it to the dealer now, or just leave well enough alone.

Thanks guys. This forum has been awesome. And do you think its worth posting this on the other popular M3 forum as well?
 

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Unfortunately there is no concise fix. You've tackled most of the common items... with how much you've spent you could have gotten a tune which we know fixes the issue.
 
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