jer4251

iTrader: (6)

just got done putting in replacement injectors and cleaning up the top of the engine. car wouldn't run prior to this. now when the car starts the engine starts revving up really high so I have to shut it down. any idea what could cause the engine to just want to take off at idle? maybe someone messed with the throttle body setting when it wouldnt run for them??

Tuned Performance

iTrader: (92)

Start with checking for vacuum leaks followed bye setting the minimum idle speed with the iac commanded in.

jer4251

iTrader: (6)

will it be ok with the engine cold? I cant run it long enough to warm it up. Im thinking I have a bad IAC valve, or its stuck all the way open. cause the car wants to rev up like were taking off in a plane. I get maybe 3 seconds of run time before It sounds like its going past redline.

Tuned Performance

iTrader: (92)

That sounds more like a big vacuum leak other than the iac being stuck open. Jump the aldl a to b and unplug the iac and try to start and see how the rpm is. Its going to be difficult to start cold if the iac is all the way in on a cold engine you may need to hold the throttle cracked off idle to get it to run.

jer4251

iTrader: (6)

jumped the aldl plug,unplugged the iac and it starts up and wants to take off still. ive traced all the vacuum lines and cant find anything wrong with them. tightened up all the plentum runner bolts. figured I had a leak there but all seems good. removed he iac and it was cruddy but was able to push it in and it moves with some force.

Ransford2987

Are you sure every vacuum connection is installed on the intake plenum? If you think the throttle body was messed with, check the position of the throttle blade during start up; or just hold it shut. If you still have a ramping idle after that, it has to be a vacuum leak, right? How else would enough air get into the system and cause the rpms to rise, unless you had a leak on the intake somewhere? Granted you are at idle, but still...

jer4251

iTrader: (6)

I don't know whats going on with this engine. im going to replace the iac sensor tomorrow. if that doesn't do it ill tear the intake apart again and start over.

jer4251

iTrader: (6)

IAC valve did no good. I don't feel bad replacing 23 year old sensors by any means but somewhere along the line It sound work correctly.

started it up to attempt to move it and it chirp'd putting it in reverse to back it up, had to shut it down and yank the parking brake to not go through the front of my garage door. it cant be sucking in soo much air that it wasn't to redline like its doing.

this thing is driving me crazy!! could the ecu be jacked up? not sure what else to look for. it ran but barely before I did the injectors. i'll have to tear it back down and redo it and see if that helps or if I missed anything,...

mmadden55

You have a massive vacumn leak somewhere, either that or you have a cruise control module that is yanking the throttle open.

jer4251

iTrader: (6)

started taking the upper plenum off and found my issue.

HUGE vacuum leak!!! you guys nailed it. although it wasn't a vacuum line as those were all correctly hooked up. I couldn't see this with the upper plenum on. she runs!!!! now on to plugs and wires.

Brycegibler

hey guys, i have the same problem i have a 1992 fire bird formula with a 305 tpi and the idle is crazy, I don't know what to check next i have replaced the iacv and reset it and hooked it up to a scan tool and it works fine, i have replaced the throttle body gaskets and left intake plenum because i could see a chunk of gasket missing there and still no luck i was thinking a huge vacuum leak somewhere but i taped up the throttle body ensuring no air could get in. If it had started then there would obviously be a vac leak but it did not this makes me think it could be the tps? I did test the tps and it was way too high so i bent it a little to appropriate volts and no luck. maybe if i buy a new one it will work? The throttle blades should be straight up but they are at a slight angle with a slight gap letting air in, the idle screw is backed down all the way so the blades cant go any further to straighten out, I am at a loss and need help. Any help would be greatly appreciated thank you.

mmadden55

sounds like you already found your problem, the throttle body.

Brycegibler

Yeah that's what Im thinking, thank you.