Another Crossfire Question. I have 83 z crossfire. it was in bad condition. supposedly only has 75,000 original miles on it. That's what the odometer reads and it hasn't been tagged since 95. Since I've got it I've cleaned gas tank replaced fuel pump, new fuel filter. New intake gaskets and rebuilt throttle bodies. I deleted all the smog system, I might get some grief for doing that. Put long tube headers on it. I know its a lot to do to a stock crossfire. Should have just rip the engine out and went with something else but I digress. New Map sensor, temp sensor, O2 sensor. Throttle position sensor is set correctly and works correctly according to my multimeter. Timing is set 6 degree BTC. Set gas psi to 13. New spark plugs and oil change. Car drives great but the idle seems to be off still. When started it idles about 1400rpm then after it warms up slow down to 1000rpm. I've noticed the iac on passenger side closes all the way but the one on the driver side is still letting air in. So i bought another IAC thinking it was bad. Well still the same passenger side closes and driver side still letting air in. Decided to jump A and B pin on ALDL to force close the IAC. Nether one closes when i jump A and B pin on. So I take out both IAC then jump A and B pin on ALDL and turn car on. Well you can here the motor pulsing on both IAC but the pintle goes out on one pulse and back in on the next pulse. Im not sure if the computer thinks the IAC are fully extended already. Maybe i need to take it on drive to reset IAC? Are the pintles suppose to be the same lenght? I was told not to force the pintle in or out. Is there a certain procedure for installing IAC? Sorry for being ignorant but these Crossfire IAC are confusing and I feel like this has to be why its idling high still.

 

If the IAC is similar to those used on other TBI systems, the pintle can be rocked back and forth slightly by hand while pulling outward slightly to relax the spring and remove the pintle from the body of the IAC. This will work the grooves on the pintle stem past the rack gears. Those are circular grooves, not threads, so turning the pintle will be of no use. You may find that the pintles need to be removed, the pintle stem and rack gears inside the IAC bodies cleaned and lightly oiled, and springs set to the same (proper) free lengths. It is likely that you will find the IAC stem dirty, and spring with a bad memory (too short):




A short spring will look something like this:



That can be carefully stretched so that the free length is correct, usually 2¼" ± 1/8". Try to keep the spacing between each spring wind approximately equal to preserve the correct and consistent spring rate:



Reassemble the pintles into the IAC units in the same manner, rocking the pintle back and forth while pushing inward. It is a slow process, but it will move inward.

Since both IACs are wired in parallel, the ECM cannot step them individually. Pulsing one IAC pulses both, in either phase (direction).



Because of that, both IACs must be clean, lubricated, and operate reliably. It is best to set the pintles on BOTH of the IAC units to the same (measured) length before installing and connecting them. Measure the depth of the recess in the throttle body and set the lengths equally, about ¼" shorter than the depth in the IAC bore. Reconnect everything before turning on the ignition.