QuestionI have a 88 deville and a 89 eldorado both with 4.5L engines. I get an intermittent code E030 - IDLE SPEED CONTROL CIRCUIT PROBLEM, on both vehicles. This only occurs when the outside temperature gets COLD 40's and below and never happens during warmer weather or when car has warmed up for a few minutes and then restarted. If I drive the car with the service engine light on the fuel economy is not good .. then after a few minutes its seems to correct the problem and fuel economy is restored. ECM input tests pass and ISC motor extends and retracts.. its must be something that the cold weather affects. What causes it to only happen in the COLD, and any ideas or what might need to be changed?
thanks
AnswerERROR CODE E030 for an 89 Eldo is: RPM ERROR TO GREAT.
There is NO EO CODES for an 88 Deville. You may be seeing an E30 code ?.
E30: ISC Circuit problem.
Either vehicle can have these codes due to:
1. Incorrect TPS settings and or intermittent TPS failure.
2. Incorrectly adjusted or faulty ISC motors.
3. Incorrect BASE idle speed settings.
In most cases it is a fault within the ISC motors, But NOT ALWAYS.
autohelp
It's called TEMPERATURE SENSITIVE and is a real PAIN to diagnose.
Most probable fault is the
