st fluctuating idle, fluctuating idle Options

[rapid36]

hey guys my 94 celica st when hot or cold will fluctuate its idle. it will bounce up and down about 200 rpm and when listening to the exhaust it sounds like it misses every once in a while. i bought new spark plugs, spark plug wires, front o2 sensor, fuel filter, and i took out the throttle body and cleaned it all up. well mainly the butterfly i didn't try taking off the IACV and cleaning it. As a side note i do not have any check engine lights on, and yes it does work.

Any ideas on what it could be?

[HaysoosKreesto]

I am the farthest thing to a reliable source for this advice, however, let me at least try to give you some ideas.

It sounds like the computer is having trouble knowing how much fuel to add to maintain idle. Flashing the ecu might work, but it could be that some type of sensor is too dirty, malfunctioning, has come loose after 20 years of life or needs replacement. O2 sensor only inspects the exhaust manifold to see if the mixture of fuel and air is running richly or leanly, so probably not the sensor your looking for.

Perhaps the fuel filter is dirty and struggling to give gas efficiently?

I don't think any compression issues are present, but it can't escape my mind, maybe check?

https://www.youtube.com/watch?v=8oJyRHaqksM

This is a kind of terrible, kind of funny but actually very similar video to your problem, perhaps check it out.

/edit: sorry, I forgot to mention that the video actually is about a honda, but the concepts are the same. He checked the car for leaks in the air intake system, contacted the dealership and produced nothing. He eventually found it to be a cooling issue. Replacement of the coolant and rad cap, burping the system and problem was solved. Not something I would of thought about, but check it out.

This post has been edited by HaysoosKreesto: Oct 31, 2014 - 1:58 AM