: slow return to idle (95 sts)



steviebelcher
01-29-04, 07:12 AM
I recently had to have the idle speed control motor replaced on my 95 sts (125K). since that time it seems to take longer for the engine to slow down to idle. it idles very uniformly at about 8-900. it is almost like cruise is engaging. any ideas?

Geno Castellano
01-29-04, 12:47 PM
I recently had to have the idle speed control motor replaced on my 95 sts (125K). since that time it seems to take longer for the engine to slow down to idle. it idles very uniformly at about 8-900. it is almost like cruise is engaging. any ideas?
Was the idle speed control motor adjusted correctly? It's easy to check. With the engine idling, depress the plunger of the idle speed control motor with your finger. At the same time, open the throttle lever slightly to elevate the engine RPM. The plunger will retract due to the elevated RPM. Let it keep retracting until it stops. Unplug the electrical connector at the idle speed control motor to "freeze" it in place at the fully retracted position. It helps to unlock the connector ahead of time and/or have a third hand here. Allow the throttle lever to slowly return to idle. At the closed bore position there should be .030 to .060 clearance between the end of the plunger and the throttle lever and the engine should be idling about 450 to 500 RPM with the AC off. If there's no clearance between the plunger and the lever then screw the plunger in to shorten it to gain the proper clearance. The exact clearance isn't nearly as critical as having some clearance. If there's clearance between the plunger and the throttle lever and the engine is idling faster than 500 or so then find out what's holding the throttle open. It could be the cruise control link is too tight. The cruise link should be adjusted with the throttle in the closed bore position, the idle speed control motor fully retracted and clearnace between the ISC motor plunger and the throttle lever. Make the cruise link just barely taut with slight, perceivable slack by repositioning the mounting pin in the sector. The cruise must be adjusted with the ISC retracted. If it was adjusted with just the key off then it's too tight and will hold the throttle open.