Very High Idle

[plowboy34]

Could someone help an old man out that don't know much about EFI. I got one idling super high, I unplugged the IAC and the TPS and it still just screams at idle. Could the IAC be bad that would cause it to do this. Thanks if anyone can help. Give me a carb anyday....LOL I know EFI better just don't know anything. It is a 92 Tempo with a 2.3

[MalcolmV8]

If you unplug the IAC and it's still screaming then your IAC might be stuck open. Remove it and see if you can visually see it suck open. Cleaning it with carb cleaner may help short term to get the little piece inside moving again. In my experience that's always been a very short term fix and it usually needs to be replaced.

[lefty]

vacumn leak...........

[plowboy34]

Malcolm, the plunger inside the IAC is not stuck open but it takes very little pressure to push it open. The local NAPA guy let me look at a new one and it was alot stiffer. Could this be the problem, I wondered if the spring action was weak and the vaccum of the engine was just pulling it wide open. I did clean it about 6 months ago but it wouldn't hardly idle then, was full of carbon and crap. That really did it wonders, but now it probably idles about 2500rpm. Appreciate the info bud.

Lefty, a vaccum leak will not make an EFI engine idle high will it? I had the same thought until I considered that, I know with a carb it will but not sure of EFI.

[MalcolmV8]

I don't think vacuum leaks make EFI idle high, at least not little ones because the ECC will just close the IAC to bring rpms down. Easy to test though, just pull off a vacuum line and see if that spikes your rpm... except yours is already crazy high.

As for the IAC. You have it removed right? Why not just plug up the holes where it attaches to the motor? Fire up the car and the idle will be very high, go plug the holes (with your fingers if its in a safe place) which should cut off that air around the throttle body blade and either kill the car or bring the idle so low it sounds like it may die. That will tell you what if any affect the IAC air flow is having on your idle.

Have you checked for codes? The magic of EFI, it tells you what's wrong with it

[plowboy34]

No I have not checked the codes, I thought you needed a special tool for that. Can it be done without anything special, would love to know how. I will try the plugging hole thing just to see what happens. Again thanks for the info.