2002 Protoge 5. When I start it up in the morning the idle is really high. About 2800 rpm. It stays like that for almost 10 or so minutes untill it finally comes down to normal. Also noticed the check engine light going on and off over the last few weeks. It'll go on for a few days, go off for a few ...and on and on like that.


What could be the problem?

 

I just started experiencing a similar thing this fall on my 2002. When it's cool out and I start the car the idle shoots up to 2400 RPM and like you say after a period of time goes back down. I'm not getting any check engine light however. I also noticed that once the engine is warm and I come to a stop it takes two or three seconds for the idle to come back down. It's a manual by the way. I hope someone has some Ideas to share on this. Thanks.

 

I would say there is a problem with the air control valve. It is likely gummed up with carbon and needs to be cleaned. It is located on the throttle body on the underside of it.

 

the high idle at red lights, where it idles high for a few seconds and idles back down is a sign of a small a/c problem. it isn't anything to worry about but the IAC should also be changed and that will cut it back a little.