Renix idle speed anamolies '89, 4.0 L

[Ecomike]

A very interesting thread. I've gone through a lot of this troubleshooting with my '90 4.0 AX-15 and have made it drivable. It does, however, have 2 distinct idle speeds, 650 RPM and 1000RPM. Temp, drive time, etc. seem to have no effect on which one I'll get. For example I'll drive it to work (highway driving, the engine gets good and hot) and sitting at the light I'll have 650 RPM one day and 1000 RPM the next. I ultimately gave up *(&*&(_ around with it but if anyone else has ideas I'm open.

The best thing to do is carry a multi meter around with you, and when it acts up, changes, pop the hood and take the same readings, O2 sensor readings, TPS voltages, MAT and CTS voltages, and MAP voltages, but mainly TPS, MAT and ground to battery negative post back voltage readings to look for a voltage change!!!