Idle Problem. Please Help
 

My Jza80 TT wont start in the morning unlless I have my foot on the throttle. When it warms up then it will idle at 500pm. It seems like the Idle control valve does not take any commands from the Ecu. Please give me a few guidelines, suggestions on where to look for the problem. Thanks

Do you have a copy of the TSRMs? I'm sure there's a troubleshooting section for the IACV. Imo, the TSRMs are a 'must-have' for all Mkiv Supra TT owners that want to do their own maintenance and modifications.

My car is Jap Specs and Jap Import. I have nothing. My michanic is unable to locate the problem and my only way is to sort out my self with the help of you guys. :(

In that case, troubleshooting will be more difficult. As a first step, I'd suggest finding another Supra owner that lives near you to see if they'd let you swap their IACV temporarily. If that fixes the problem, all you need is a new IACV from Toyota...

have you tried running a diagnostic?

It may be your IACV(idle air control valve), but is there a problem with idling once the car is warm?

I know you said it idles when it is warm at 500rpm but do you notice any flutering at all? Anything different? Is it at all slugish?

Its just kind of odd how the IACV works fine once you are warm but during cold start it doesnt seem to work.

Do you notice any wires loose? Did you have any electrical problems before? I would try changing the IACV first then if that doesnt solve the problem we can trouble shoot some more.

Is there an echo in here?

we won't really know much until he does at least a diagnostic... it very well may be the isc but pulling codes is always a good first step

Agreed...if your Supra's ecu has any codes, it's always a worthwhile exercise to go through them first. Although you didn't mention the check-engine light, please post any codes stored in your ecu and we'll help you make sense of them.