AFs2k

I was driving to get dinner with a few friends. While on the highway, I would let off the gas and the car seemed to go by it's self. We got off the highway and at a stop the car would rev by it's self from 1k to 4k continuously. It was like someone just sitting there reving for no reason. We pulled into a parking lot and checked everything, vacuum lines, map sensor... you name it I had my hand on it at least once.

Well, I needed to get the car home, so I drove it back. F'n scary. And of course there would be constuction going on so it was stop and go with a car with a mind of it's own. Well on the way back the check engine light came on, it was codes p1129 and p0108. I know those deal with the map sensor. I changed it out for a good one... and reset the ecu. I turned the car on and it still sat there and reved by it's self.

I took off the IAC and cleaned it and installed it again. But I didn't get a chance to turn the car back on, because my manifold cracked so I had to remove it to get it fixed. I think the manifold cracked because of what happened. I don't think it was the cause.

I can't figure this one out guys... I need help. Any insight?

Importedpower

Just an opinion, and Ive seen it before on my boosted GS R... turbo's kick a lot of fun "shit" down your pipes and builds up a fantastic layer of this black, sooty carbon in your intake mani. Even with new sensors and such, if the carbon is built up/clogging the intake mani, guess what? its still not going to read for crap. I would pull off the intake mani, since your turbo mani is cracked anyway, you have the free time. I have a parts washer, and i left my mani in it with a tube run inside of it to let it continuously flush out over night, reinstalled, and boom. worked. No promises, but try cleaning it out

oh, and btw, what year?

AFs2k

I suppose it could be crudded up... even if I use 93 or higher octane though? I don't think it'll be because of the intake manifold gummed up though, the map sensor is in the throttle body.

When I pulled the IAC it was clean... This is lame.

By the way, it's an '05.

AFs2k

Intake and throttle body are super clean.

Anyone?

AFs2k

up....

Billman250

What do you mean the manifold cracked??? Cracked because WHAT happened....

Revving by itself is a stuck IAC valve.

AFs2k

I believe the manifold (exhaust manifold for turbo) cracked because of what happened. I mean, revving continuously at every stop light, non stop revving. It wasn't cracked until all this happened.

A stock IAC would cause it to just keep revving to 4k? I figured if it was stuck it would cause it to stay revved in one spot, no? Would that also throw those codes? I mean, they both deal with the map sensor and not the IAC. You'd think maybe I would have gotten one for the IAC if it was really the problem?

Importedpower

i think the mani was probably already cracked, the cause of cracking is heating and cooling, if the car was running steadily then it wouldnt be cooling much, and reving up and down wont cause that either if the car is already warmed up. now driving in 20 degree weather, parking, killing the engine immediately and poping the hood up to look at it might cause it to cool too fast

Billman250

You will not get a code. And yes a stuck IAC will cause idle to go up and down like someone is revving the engine.

AFs2k

Thanks guys.

Guess when I get my manifold back, I'll see if me cleaning it did anything and I'll report back.

You think I should just say screw it and get a new one?