Erratic Idle

[SHOguy 92]

Well Got my 91 back together now after fixing the transmission (I hope). Fired it up to see how everything works and it runs so rough "blap blap vlap" and the idle bounces from 1000 to 2500 rpms. Under load it seems fine, but it really can't idle, any ideas? It has only 1 front exhaust stud and is leaking really bad, I had it quieter before so I'm gonna try and get it better secured today, but could a big gap up front cause it to be that bad?

 

[SHOguy 92]

Would an exhaust leak up front cause it to run this horrible?

 

[SHOguy 92]

Looked at it some more, still bounces between 1000 and 2500ish. it starts at 1k and is running very rough going from like 800-1200 then starts jumping from 1000 - 2500 and will just keep doing that. And sometimes it will all of a sudden make a beeline for redline and you have to turn it off. This is with the car not in gear and not depressing down on the pedal at all. Anyone?

 

[1993MTXSHO]

sounds like it could be the IAC. Idol air bypass, its on the intake manifuld right near the throttle body.

 

[SHOguy 92]

Hmmm, I know that can be cleaned but how and with what solution? Funny thing Is I had this car running a week ago fine with no 5th gear or reverse so I dropped the tranny and fixed it, and now it does this, but I suppose like everything else it can go bad instantly too.

 

[SHOguy 92]

Ended up being the cam position sensor, so happy I found out what it was, now I gotta order another. Man that is the worst noise I have ever heard coming from a healthy motor.