'93 Allante stalls at idle with a\c

drivestregis · #1 (**permalink**) 07-27-04, 11:05 AM

1993 Allante with Northstar, of course. Engine stalls when car is in drive (with brake engaged) and a\c is on. I have changed idle control motor. Mechanic says no codes are coming up and can't figure out cause.

BeelzeBob · #2 (**permalink**) 08-02-04, 03:51 PM

Is the idle speed control motor working and adjusted properly??

To do a quick check open the hood with the engine idling in park with the AC off. Hold the throttle open slightly with your hand on the throttle lever so as to elevate the engine RPM to 2000-3000 or so.... Simultaneously depress the plunger of the idle speed control motor with your finger......it should start retracting. Allow it to fully retract until it stops. "Trap" it or "freeze" it there by disconnecting the wire connector at the idle speed control motor. Slowly return the throttle lever to the closed bore idle position...i.e..release it onto the fixed stop on the other side of the throttle body. The engine should barely idle at about 450-500 RPM. If it repeatedly stalls or just will not idle then possibly the throttle body needs to be cleaned and/or the closed bore air rate adjusted. When the throttle is at the closed bore position there should be about .030 to .060 inch clearance between the throttle lever and the plunger of the idle speed control motor. There absolutely must be clearance between the idle speed motor plunger and the throttle lever...but not too much.

Does the AC work OK...????...i.e....are you sure the AC compressor isn't seized and stalling the engine when the AC is turned on...??? Elevate the RPM and turn on the AC so that the engine does not stall and see if the compressor is turning and quiet.