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Finally Running! Warm up idle?

82GLT

82GLT

Member
Joined
Jun 17, 2016
Location
Gresham Oregon
Warm up idle;
Pre rebuild the car didn't do a warmup idle just sat at a set idle 900/1000 and warmed up itself and now post rebuild its all set and when it starts cold it'll sit at about 450rpm which causes me to hold it at 1500 or so until its at operating temperature then goes back to 900/1000

Any ideas why its idling lower when its cold and not visa versa?
Idle set at operating temp 900/1000 RPM at 12?
 
Check harness plug for idle air valve. One wire might be disconnected, causing the valve to close. Another possibility is that the plug has fallen off. When my previous '82 242 Turbo had the plug become disconnected, it'd "idle" at 200 rpm when cold, then have a slightly high idle around 1100-1200 rpm when warm. During the cold idle, it'd never die, just would run at a very low rpm compared to my old '83 245 Turbo, which I had at the same time. Reconnected the plug while working on it one day, and it started running normally.
 
Any idea where it might be or look like?

John242Ti said:
Check harness plug for idle air valve. One wire might be disconnected, causing the valve to close. Another possibility is that the plug has fallen off. When my previous '82 242 Turbo had the plug become disconnected, it'd "idle" at 200 rpm when cold, then have a slightly high idle around 1100-1200 rpm when warm. During the cold idle, it'd never die, just would run at a very low rpm compared to my old '83 245 Turbo, which I had at the same time. Reconnected the plug while working on it one day, and it started running normally.
Click to expand...
 
I'm not a kjet fellow, but the idle air valve in any car has to be near the throttle plate. It's purpose is, as the throttle plate closes, the idle air valve opens to act as a bypass around the throttle plate to ensure the motor still receives enough air to idle.

They're also commonly referred to as idle air control valves. Usually has a length of 1/2" or 3/4" rubber hose going from the intake side of the throttlebody to it, and then from it to the back side of the throttlebody.

Don't know if this is it... but this will get you looking.
IACvalve.jpg
 
Apparently kjet used 3 port and 2 port variations. That pic is from Dave's site in reference to wire harnesses and has another couple of pics that may prove helpful.
 
All of the kjet idle control motors I've ever seen are three contact motors. The constant idle system as volvo calls it was used on the 1982 n/a kjet engines in the US and on the turbo. It is exactly the same system on both cars just different location of parts on the engine.

The high idle from the constant idle system is determined by the engine temperature sensor. If that circuit has the wrong impedance then the control unit won't think your engine is cold. So you don't get a cold high idle. It is either a bad or wrong resistance sensor or there is some other issue with wiring or the controller.
 
^Typically, when they fail, they fail in the absolute zero range, temperature-wise, so "idle" is 3200 rpm, not the 200-500 rpm the OP is seeing. Also, if the wrong sensor is used (say a 1981 sensor with a 1982-85 box), it'll work OK, but the engine will tend to hang at a higher rpm when shifting for a second or two, then drop back down. Using a 1982-85 sensor with the 1981 box is no problem. Done that before on turbo cars, since they don't have the AC idle bump feature, instead they run at 900 rpm all the time, like a California-spec 1981 non-turbo 240 with Bosch ignition.

-J
 
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