another strange occurance

[gw84]

very rarely this happens to my car. When I start the car, the engine races up real high and then slowly comes back down to normal. It usually only takes it about ten seconds to return to normal idle. If I put the car in gear while it's doing its high rev thing, the car lunges forward and usually dies. Because of this I usually just let it rev high for the few seconds, wait for it to calm down and return to normal. Does anyone have any idea what is wrong here? It only does this about once every two or three months. I am so confused on this one.

[richtazz]

A racing idle that settles down is usually a bad or sticking IAC (Idle Air Control) motor. It's a small stepper motor that works similar to a choke on a carburetor, regulating the amt of air allowed into the engine at idle and part throttle.

[gw84]

how much do they generally cost to replace?

[richtazz]

The part is about $40, and it is ver easy to install. It is mounted to the throttle body with 2 screws. Make sure you clean out the passage it is in, so if there is carbon build-up, it doesn't make the new one stick.

[gw84]

thanks, I'll look into that