My car was having problems with high idle
and the speedometer would only work once
in a while. I just replaced the ECM and
everything is working again all except the
high idle. When I start the car it runs at 3000
rpm and when I drive it around it ildes at
2100 rpm. I have no vacuum leakes
anywhere. Please help.
check for codes. google, "how to read gm obd1 codes" could be throttle position sensor or idle air control valve.
It's got a new idle air control valve and the service engine light is not on. Could a blown donut gasket cause the high idle?
Not sure what you mean by "donut gasket", but check for codes whether the light is on or not. Try cleaning the throttle body.
It also occurs to me that since you replaced the ecm, you may have to do an "idle relearn procedure" google it for your gm car.
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