ok, fist off what the heck is it? As the name states I would think that it has somthing to do with the idle and how it is set. But in my car it does not seem to do jack squat. In fact the thing is so useless that i disconected it tonight. Turns out that with it hooked up the cars RPM will go up pressing on the gas and if i stop it going up at 2000rpm it will stay. Goes up to 2000 then does not move. Same thing with 1500rpm or any thing else. Goes up then stays. On the other hand if i gun the car till i redline the thing will then go back to idle at 1000rpm But if i gun it and do not redline it the thing will idle at 2000rpm. So after spending !15$! on a junkyard replace i was so pissed that i disconnected the idle moter. The car now idles at 1500rpm no matter what I do to the engine. So again what the freak does the idle control moter do? If i want to adjust the idle i fiddle with the throttle body. If the mother remains hooked up my car idles all over the place. If there is any one that can tell me the mechanicks of what is going on i would be infaniatly gratfull. Specificaly i would like to know the relashinship of the idle adjust screw, that switch on the throttle body, and the idle control moter. What do they do, how they work, and from that i might be able to figure out what is oing on and maby how to fix the thing. Sorry for the long post but i seem to have a rather strang problem opn my hand. thanks in advance.

One observation from me and my used Volvo parts guy. Used CIS motors are almost always junk. Even if they are working when the car gets scrapped they tend to stop working after sitting for a few months. My parts guy does not no why but thats what he has found. I sort of didn't believe him and I went though most of the CIS motors he had. I have got one that lets the car idle at 1500 rpm but it does not do anything. If you have eliminated everything else you are probably best off getting a new one.

The idle control valve (sometimes called the CIS motor or Idle Air Valve, IAV) is an electrically-controlled valve that bypasses a small amount of air around the throttle butterfly. It's controlled by the FI computer. This permits the computer to control the idle speed.

Three things (commonly) can cause the valve to malfunction. First, the valve itself can be NG. The brushes and commutator burn through. On an '84 car, probably with high mileage, this is most likely the cause. The only remedy is a replacement valve.

Second, the idle switch might be defective or misadjusted. This can also occur if the throttle body is varnished up so that the throttle does not fully close. The throttle switch, which "clicks" (turns on) as the throttle returns to idle position, tells the FI computer to start controlling idle. If the switch never clicks, the CIS motor is never engaged.

Third, a crumbling wiring harness might have defeated either the switch or the motor.

When I bought my '86 the idle was not controlled, even with a new motor. It turned out that the PO's meathead mechanic had simply adjusted the throttle mechanical stop to compensate for a bad motor and varnished TB. The result was that the switch never clicked. Even worse, the throttle had been adjusted open, so I had a 2000 rpm idle. A thorough cleaning and complete readjustment of the linkage and throttle stop restored it to perfect (and properly controlled) idle.

Don Foster (near Cape Cod, MA)