1981-1983 Imperial Automatic Idle Speed System

Imperial Home Page -> Repair -> Fuel -> 1981-1983 Tips -> Automatic Idle Speed System

Tip from Dick:

The AIS motor hangs under the HSA, at the front of the throttle body casting, to which it must be fastened tightly or you will have an erratic idle. It is a rectangular case about 1 1/2 X 3 X 3/4, with an arm coming out of it going to a long screw and turnbuckle arrangement which is connected to the throttle shaft lever at the right side of the intake manifold.

This is where you adjust your idle speed, by the way. You turn the end screw (5/16 capscrew), each turn changes the set point for the warm curb idle by 50 RPM.


Addition from Dick:

Sometimes this hunting up and down in idle speed is because of slop and lost motion in the Automatic Idle Speed system. Next time you experience this, reach under the left front edge of the air cleaner assembly and push on the linkage that goes from the idle speed motor to the throttle shaft in such a way as to take all the slop out of the mechanism. This requires a steady push of maybe a pound or so, and it gets hot in there so wear a glove, or push with a long screwdriver against the idle speed adjustment screw (you have to weave it through the heater hoses etc from near the end of the dipstick). If this smoothes things out, you could try to rebush the joints in the linkage, and make very sure the idle speed control motor is securely fastened to the throttle body, they do work loose over time, adding to this problem. BUT, be advised, the hunting up and down of idle speed is one of the endearing characteristics of this car, and they all exhibit this to some extent if the AIS is working properly. Hunting around from 700 to 800 RPM is not all that unusual.

I was going to see if my spare idle speed motor worked or not. The throttle plate in the car it came out of was seized which caused the car to idle at a high speed. It was rusted bad, I had to put it in a vice and hammer the sleeve out. Relubricated it and it looked like it should work fine.

I went downstairs to get the idle motor. I couldn't remember whether it worked or not. Not!!. I tried a 6v battery on it.. nothing happened. Then I tried a car battery with a 10 ohm resistor is series.. nothing except some sparking when connected ( which indicated there wasn't an open circuit). Next I removed the four screws and took of the cover. Things looked OK except it the gearbox was dirty. There is an opening in the box that lets in dirt. I connected my little 6v lantern battery and could see the motor just barely turn. Reversing the leads it turned the other way. From this I knew the motor was OK and the gear box was seized. I sprayed the gearbox with carb. cleaner and applied 6v, and kept reversing the leads when it stopped. After 10 or 12 times it loosened right up and appears to work fine. I cleaned out all of the old grease and dirt and regreased it. The arm only goes so far each way and then hits a stop. I think the current limiting ballast resistor may have saved the motor from burning out when the gears became seized. This could be what's wrong with yours. You'll have to undo the two screws holding down the idle speed motor and use needle nose pliers and or a screwdriver to pop off the connecting rod. Take it inside and undo the four little screws and take a look. If the motor is bad you can take this one I have here and give me yours in return. I think I can either fix or find a replacement for the reversible dc motor....I found a spare motor just now in my junk pile. There 6v reversible motors made in Hong Kong, about 5000 rpm or 80 rev/sec. So check out the motor and get back to me, it comes off pretty easily.

This page was last updated on August 26, 2001.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club