70351cmustang

Just bought a 88LX 5.0 5spd (speed density) and have a problem. When the car is cool it runs fine but once it warms up it has an idle problem. When coming to a stop sometimes the rpms drop to 500 or below,but the car does not die it may do this 2 or 3 time then clear up on its own. I have tried to rev the motor up when this happens but the rpms will drop again. This doesnt happen all the time,so i dont believe it to be a gasket or vacuum problem. So far the tps is set at 1.19 volts at idle,is this too high?? Have already done complete tune up (cap,rotor,wires,plugs) and have installed a new IAC. Anyone with any ideas??

gmkilla

I know on my car the voltage at the TPS should be .6, thensmoothly increase to over 3 volts, if my memory is working tonight, i think 1.19 is way too high, but i could be worng be cause i'm a mass air guy, but other than that i really dunno what to tell ya, no ideas now...but i'm tired
killa

roundman

that's too high a voltage with the throttle closed. it should be only .98 volts with throttle closed back against the mechanical stop screw. you probably need to pull and clean the throttle body good, especially on the back side of the butterfly. then pull and clean the IAC with some carb cleaner. reinstall both and then reset the TPS to this voltage, and then disconnect the negative battery cable for at least 10 minutes to clear the KAM in the ECU and reconnect it and see how it idles then.

70351cmustang

Got it figured out guys...Thanks for your help. Here is what i done maybe this will help some one else out. Start car let it reach normal operating temp. Then disconnect IAC (idle will drop) then adjust idle screw under throttle body set it to 850rpm reconnect IAC (idle will rise) shut car off. Next turn key to on position and set TPS voltage (I set mine to .975). Then turn key off and disconnect the battery for about 15 min. Reconnect battery and drive it like you stole it!!! Hope this helps someone else out..