Hey guys, my girlfriends dad just traded for an 84 crossfire. Brought the car home ( 30 min drive) washed her up and parked her. The next day went out to find the car idling around 13-1500 i believe he said. Which is being caused by both throttle bodies sucking a ton of air from the spot in the pic below. He stuffs a shop towel in each part and the idle drops. So my question is.. is this the infamous worn tb shafts ive read about? IAC? or something totally different?
Hopefully the link eorks! Thanks guys


http://m635.photobucket.com/albumview/albums/jtoombs_vette/1334210780593.jpg.html?o=0&newest=1

 

The main cause of high idling on a crossfire is due to a vac leak. A common location would be from the shaft bushings. If you have a lot of play in them its time to get the rebushed.

 

One other common place to look for leaks is the plenum lid gasket.

I agree with qws; look for vacuum leaks.

 

Is each IAC functioning and not stuck wide open?

One of mine was dead and stuck closed once.

Ign on engine off you should be able to to see them cycle closing and opening to what steps are commanded. Look down the air pathway to see the pindle move.

 

Ok thanks guys. Did the link work? Because that is where both tbs r leaking from. I guess i could try replacing the IAC first but my guess would be the tb shafts worn seeing how common the problem is.

 

I think DCTrumpet on 3rd gen does the TB add on of a bush. But any carb shop can do as well. GM had no bushing in place.

 

The link works. They are pretty much always going to "leak" from there. In other words, you will always hear air flow through those ports. In there, is a pintle/needle valve that is controlled by a stepper motor called the Idle Air Control motor(s). They "throttle" the motor during idle to control engine RPM. When the engine is warm, running efficiently, and at low idle, the air flow through there will be very low...just a whisper, audibly. When cold though, the air rushes through there aggressively and makes a lot of noise.

If you have a vacuum leak, the IAC's cannot control engine speed. Do you have access to a scan tool? If so, you can look at the IAC's in "Data Stream" and see where they are supposed to be. If you see something like 11, 12, etc. then there should be little air flow through those ports. 20+, and they'll be roaring.

The IAC's can get out of whack and resetting them requires driving briefly at speeds over 30 mph.

Try ^that^, look for vacuum leaks, try to determine if the IAC's are stuck or working, and report back.

P.S. I personally don't feel that Throttle shaft wear is that big a problem. Yes, they wear...but that generally doesn't cause GROSS loss of engine speed control as is the case here. I've seen CFI cars that had very sloppy throttle shafts -to the point where the throttle would bind near closed!, and still idled perfectly fine.

 

Ok ill do as u suggested with the IACs and get access to a scan tool. Ill also take a video when i get a chance and hopefully thatll shed more light on the situation. Thanks again for quick and detailed responses