joseph ... 4/20/2013
1999 Saturn SC1 Base 4 Cyl 1.9L
Idle's too high
When the car is just sitting,it runs perfect,at around 10,000 RPM,but once the car is in gear and move,it rises up to 20,000 or more,(depeding on escalator and the speed),it wont go back normal until I come to a complete stop and wait 5 to 10 second then it goes back normal.,believe it or not,it even does it when the car just plain coasting,I am sort of a machinac(,but this is one wierd'es piece of junk I have ever been into).,The car has got 140,000 miles, I have check all over the engine,replace the TPS,and IAC,but still not much changes,somebody gave me a suggesting that I may need to replace coil pack,.My questoin to you is it possible that it could be the coil pack ??.
If you have already replaced the IAC (idle air control) valve and the TPS (throttle position sensor) then the issue is most likely related to a vacuum leak - have you tested for cracked or broken / deteriorated vacuum hoses? I'd check for this condition before replacing the ignition coil pack - as this (coil pack) would not really caause the high idle condition.