92 z34 idle problem

[JH]

The first time i start my 92 lumina z34 during the day it will rev up to 3000rpm in park and neutral and start bouncing off the rev limiter. It will usually go away after i drive it for awhile then put it in park but after about 2min it will rev up to 1500rpm and the service engine soon light will come on. I already replaced the IAC and the TPS but it did not fix the problem. If anyone knows what could be causing this i'd appreciate the help.

[dohcfiend]

sounds like it could be an intake leak. i just had one not too long ago. it would rev up to 3-3500 and die. i had a very big leak yours could be smaller hence the car not turning off. what is the code?

[JH]

The code was for the IAC and the TPS I changed them but it still says the same codes even with the new sensors. It will rev up sometimes then you shift it in to drive and you can barely hold it back with the brakes because its reving so high and then all the sudden the rpm will drop so low that it will stall on you.

[JH]

I bought some throttle body cleaner and a new air filter for it to try the fix the idle problem hopefully it will so i won't have to spend a lot of money on it but something tells me i will.

[dykz34]

You might have to do the intake gaskets. It sounds like a vacuum leak to me. I assume you've already checked to make sure all your vacuum lines are intact and in good working order?

[JH]

Yeah when i checked them they all still looked good but i might have overlooked one of them.

[blk92z34getrag]

There are two little itty bitty lines on the left back side of the plenum hooked up to a sensor you may have overlooked. Those will really fuck up the running of your engine if they pop off. I got little hose clamps to hold them on. In fact, I have hose clamps on everything (I redid all of my vacuum lines except the brake booster line, that's just a new stock one).

[bubba81]

does it idle like that at nop or cold?

[JH]

It only revs up really high the first time you start it up during the day after that it idles around 1500rpm in park and neutral but if you let it sit for 12 hours or so and start ip up it will rev up to 3000rpm and bounce off the rev-limiter

[blk92z34getrag]

Hm... I think the Neutral/Park limiter is 4000RPM or somewhere there-abouts... When you first start up the car it is actually normal for it to idle high for a minute or so, it's to help warm up the engine, and reduce emissions. But still check gaskets and vacuum lines.