I reset my IAC, reset TPS voltage to .540 but yet, my car still tries to idle at 900 RPMS...in OD. When i did the IAC it barely idled i had it so low, then finally died. So i figured that i was good to go and did the TPS. It ran fine for the 1st startup and drive, then after i shut off the car it will idle up to 1000/900. Seems like no matter what i do, it idles at 900, sometimes it will idle at 600 (+/- 50 rpms). I took the throttle body off to replace the bolts (some were old and broke off) and cleant it with MAG1 Throttle Body Cleaner. Help someone the 1,000 rpms in drive sucks big time when trying to stop.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR

 

Branz,

The ECM will not step down to target hot idle speed (650-700RPM) until the coolant temperature sensor is at or above 176°F. Up to that point, the idle will be higher. Also, if you have the heater controls set to DEFROST or BI-LEVEL the AC compressor is supposed to run. Whenever the AC is supposed to be on, the engine will idle about 100RPM higher.

Another thing to remember is that if you have installed a higher slip/stall speed torque converter the idle speed will be slightly higher.

If all those conditions are solved, teh IAC might be sticking or there may be deposits in the IAC air passages holding the IAC pintle off the seat. You also need to be sure the TB gasket is not leaking and the throttle plates are not binding and sticking open. A frayed throttle or cruise control cable can also stick in the housing and hold the throttle open slightly. Make sure everything is clear and free-moving, and that the throttle plates are correctly aligned in the bores (not binding).

If all of those things are O.K., there is not much left to look at but vacuum leaks and a failing IAC stepper motor. You could try to lightly lube the IAC pintle worm gear to make sure it can move freely, but I'm guessing you've already done that if the throttle body was off.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

Actually i didn't directly touch the IAC motor. When i touch things like that they intend to break on me and i become broke. Guess i'll have to inspect the problem a little closer. I only have a Dayco (i think that's what it is, couldn't read the writing) 2000 stall conv. and a 180* thermo so i guess it is possible my car isn't fully warming up in the winter since last winter i had a thermostat stuck closed but open enough to flow coolant, in which case i didn't realize till spring when temps got into the 70's. I will look further into it though, just wondering what would cause the problem or if it is even one.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR