High Idle Problem

[badbradtn]

OK, I've had a high idle problem for about 9 months now. I give up trying to figure it out. My idle will not drop below 1000 rpm, even after it's warmed up. It seems to be better on warm days, cause on colder days it will stay up around 1500 sometimes higher. I used to be able to hit my gas when it was stuck and it would come down, but now even that doesn't work. And on some occasions I'll press the clutch in and it will literally bounce up and down from 1000 to 1500 over and over till I engage the clutch again. I've done all these things below and now I've got nothing else.

I've replaced the throttle position sensor, checked for snags in the throttle cable, cleaned my throttle body, replaced Idle Air Control valve, checked for vacum leaks, checked to make sure the IAC was getting current through the wiring harness and still nothing. The only time it seems to be working fine is when I cover up the hole in the throttle body that leads to the IAC, which I thought would mean my IAC is bad. But I replaced it and I have no change. HELP pleaaaaase

[Brian R.]

Check your thermostat and your coolant temperature sensor. If one of these is bad, your engine may stay cold or think it's staying cold and keeping your idle high. I would bet on the thermostat from what you've said.

[badbradtn]

Brian,
I thought about thermostat and also repalced that, I forgot to include it. But the coolant temp sensor is a good idea. I didn't think about that. Where is it located on the 3.4 Tacoma????

[Brian R.]

Top of the engine just behind the upper timing belt cover and the fuel pipe and next to the upper water hose inlet.