I have this problem with the idle and read other forums and see that Mits has this common problem. My car when started revs high to about 3k and goes down. After the engine heats up the erratic rpm's kick in, bouncing from 1200-2000!! I have tried numerous things like replacing the Airflow Sensor, The TPS and as a result of this problem now another transmission!! Only have 114k on the vehicle and plenty of MAJOR things have been replaced. New tune up, Head Gasket....I have a manifold crack and was told this problem could be caused from the O2 sensor....think that might be it?? If anyone could help, would be greatly appreciated. If at all could you be detail as to any other problems it could be. Thankx.

 

IAC maybe?

 

I have tried the IAC and it wasnt that.....anything else?? give me a couple things that it could be.

 

a bad MAF?

 

i replaced tps, mass af sensor......anything else??

 

I had to replace the intake manifold gasket on mine and that solved my high RPMS.

 

Well is there a way to test if infact it is the Gasket??Like sprayn throttle body cleaner around the housing to check for leaks?? and will it fix the fluxuating rpm's the bounce up and down? i appreciate your time

 

You can try that to see if stalls out any, I didn't get any luck with that cause mine was on the bottom so I couldn't really spray there easily. The way I found mine was by having my friend use a smoke tester which is kinda like a fog machine and it showed that there was a leak coming from the underside. It just basically pushes smoke through the intake when the car is off and if there are any leaks you can see the smoke coming out. If you don't have anything like this you can take it to the mechanic to have them do it. I think the ones around here charge about 75 bucks to do it, just general service charge. If they do find a leak, change it yourself, its really not that hard, and the gasket cost about 15 bucks and I think they wanted to charge me like 250 bucks to put a new one on.

 

Oh and the fluxation is probably due to your engine trying to compensate for this extra air thats coming in somewhere when it shouldn't be. Mine did the same thing with the bouncing and stopped once I put the new gasket on.

 

Well 15 bucks isnt anything compared to what ive spent. I will try that and see what happens. Thanks for the advise i will get back to ya when completed.