Idling at 1700-2200?? Help!

[Melvin_91GT]

Good afternoon all. I've recently started having some problems with my idle (only when the car is up at operating temperature) surging up to 1700-2200 and not coming back down. It will even do this while the car is in gear and seemingly "drive itself" if I let off of the throttle. Any ideas what could be causing this?

Just last weekend I did a complete tune-up (plugs, wires, oil, air filter, cleaned TB) in the hopes that it would solve the problem. The only thing that I forgot to do and will be doing later today is making sure that the TPS voltage is set correctly. Could this be the problem? Or, is there something else that's causing this.

It's really annoying, especially at stoplights when the idle either stays above 1500, or, drops to it's set 800 and then jumps back up to near 2000.

Thanks for the help!!

 

[Venom4.6]

IAC valve could be stuck open. Take it off and clean it with Carb Cleaner. Also clean the seat on the TB. Check your throttle cables and TB operation.

Here’s how to properly set your idle:
1. get engine to operating tempurature. turn off ac, radio, etc.
2. disconnect IAC (idle air contol soleniod) wiring harness. if engine stalls turn throttle stop in one full turn and restart engine.
3. set throttle stop to desired idle speed (rpm)
4. set throttle position sensor anywhere from .96 to .99 volts. loosen the mounting screws and lightly rotate the sensor till the voltage is within range (use a mutimeter to check as your rotating). you may have to drill out the mounting holes on the TPS to reach the desired range.
5. turn off engine. disconnect negative battery cable for 15-20 minutes. tap the breaks to ensure all capacitive power is lost. This will reset the computer to factory defaults.
6. reconnect IAC. then connect battery cable.
7. restart engine and drive for about 15 minutes so the computer can relearn any settings that have been changed since factory.
8. if problem persists, inspect for mass air meter problems and possible vacuum leaks.
A quick check also is to turn the key to the on position but not starting the engine. then check your voltage on the tps.

You may have to perform this procedure a couple times till the rev down is correct.
The first time i did this my engine would take about 7 seconds to rev down from 2000 rpm. This was due to the throttle position sensor being out of time(range). Careful when tightening the screws back down because it will want to rotate in that direction.