Idle and drivability problem

E28 technical advice asked and given! Troubleshooting, modifications and more.
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raztaz
Posts: 73
Joined: Aug 13, 2011
Location: The Mile High City

Idle and drivability problem

Post by raztaz »

I started having an engine idle problem after removing the a/c compressor( not sure yet if that was related or not) when I started the engine the RPM raced to around 3500. That finally went away after repeated starts and stops and I figured it was ok. When I took it out to drive it quit while I was waiting at a light, it started up right away and ran fine all the way home.

Today I took it out and it stopped running at around 40 mph and again started up and got me home again. Looking through Bentleys it looks like the Motronic controls the idle speed. Has anyone had this happen and was the Motronic control unit the problem or something else?
Mike W.
Posts: 27986
Joined: Feb 12, 2006
Location: California Whine Country

Post by Mike W. »

Motronic may or may not control idle speed depending on what model you have, but if it's going to 3500 you either have both a misadjusted TPS and a major vacuum leak or a kinked throttle cable/connection. Electronically it won't idle at 3500.
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