i am having an issue with an rpm surge. it revs itself up to about 1500 and does this repeatedly. it does it in neutral and when it is in gear anyone know what the problem could be?

 

more info would help, year of car ? engine ? transmission ? any mods or work done recently ?

 

it is a 1994 camaro z28 lt1. it has no recent mods. last thing that was done was straight pipes but it started before that. no other mods have been done in a while

 

Sounds to me like it could be a malfunctioning IAC.

 

that is the same thing that i was thinking but i have already replaced that. it was replaced while this problem was going on. could it have anything to do with the spark in the distributer?

 

I've been researching trying to find the cause of a similar surge on an LT-1 Vette that I'm looking at. Another thing to look for would be a vacuum leak, either a line, fitting, or a gasket. On corvetteforums.com (a sister site to this one), one suggestion was to spray some starting fluid at different areas of the engine, like the intake manifold gaskets, around the fuel injectors, vacuum fittings, etc. It was also suggested to wedge something (screwdriver) in your throttle arm or wedge the gas pedal to have the engine run at a consistent 1200 rpm's. The engine wants to be off-idle to best find a vacuum leak. If you spray the starting fluid and you can hear the engine speed up, then you found a leak. You want to go slow, spray one spot and wait, then go on to the next.

 

Try the IAC valve, new plugs and wires. If that does not help, the Opti may be at fault. The PCM gets the RPM signal from the Opti, and when the Opti gets corroded internally, this signal gets erratic causing the PCM to think the RPMs are dropping. The PCM reactsby signaling the IAC to compensate by openingwider for no good reason.

 

i have already checked for vac leaks and i cant find one anywhere. i have replaced all plugs and wires and the surge is causing a missfire. im runnin out of stuff to check that would cause a problem like this. i was going to jus put a msd ignition package in it and see if that will do anything but i do not want to spend $500 if that is not going to fix the problem.

 

It is not your ignition... Listen to the people saying IAC... It's either that or your MAF. In my case, it did the same thing and it was my MAF sensor so try that

 

i meant the distributer package. i have already replaced the IAC so i guess i will try the MAF. THANKS