86gt5.0HO

I have been noticing a high idle problem on my 86 GT once it is warmed up. When the engine is cold it run okay but when it is warm and you put it in park it revs to 1300 and then down to 1100 and stays there. Once it's at 1100 the only way to make it come back down to 800RPM is to either wait a long time (like a few mins) or unplug IAC. When I unplug the IAC it goes back down to 800RPM.

I have replaced the: TPS, IAC, and IAT

So what I can see from this is that something in the car is sending a signal to the IAC when in fact it shouldn't. What types of sensors could cause this? Or could it be the computer?

Thanks

Rick Nagel

Pure5.0

First off if you think it is the computer just unplug the battery for about 20 mins to clear the memory in the computer.

But I would take a look at your fuel pump and vacuum lines. Make sure all line are good and not plugged or cracked. Also check your fuel pump for signs of failing.

Hook up a A/F guage to your car to see if you car is running lean. A lean engine WILL create a higher RPM...but that doesn't mean it is good for it either.

86gt5.0HO

But the problem is the fact that the IAC is opening at idle when in fact it shouldn't. At least that is what I think. It only does this when the engine is warm.

86gt5.0HO

I took the batt cable off over night to clear the memory. But when I went in to town today it started idleing high again just like before. I set the timming and idle properly. I idles good when the engine is cold but as soon as it is warmed up it idles high. The strang thing is that when I unplug the IAC the idle goes back to normal, and when I plug it back in the idle goes high again. So something somewhere is causing the IAC to open when it shouldent. Could the coolant temp sensor do this? Any help is appeciated.

Thanks