I was worderning if the IAC is suppose to stop spinning when you try to set the IAC? My problem is that I took the IAC out of the TB and hooked it up to the connector, and tried to (not exactly set the IAC), but the problem is that it spinning outward. Is it suppose to do this? I am having hard time trying to figure out why my engine idles bad at idle, but has alot of power when you give is gas. It feels as though there is a miss. Also I get a loud sucking sound from the front of the TB. I check for vaccum leaks and could not find any. I tried connecting the vaccum tube to best way I could figure out. I check the TPI runners for gasket leaks. You can see the engine shake at idle, like it is straving from something. I can not figure it out!!! My idle when I have it in drive tends to go up and down (1000-650 rpm)sometimes. Like I said before, do you think it is a bad IAC, or something else Like a hidden vaccum leak?


Thanks for the help,
RPettway

 

forgot,

I have an 1987 trans am stock 305 TPI engine!

Thanks,
Rpettway

 

If you took the IAC motor off the TB like you said and started the car with the motor plugged in, then yes, the pintle will extend, since you have pretty much opened up the Idle Air passage, the pintle is extending to try to close it off and bring down your idle. You might have damaged the IAC by doing that. I would replace the IAC, set your minimum air, and then check your TPS voltage IAW the article in the Tech Articles section. Also, TPI sucks gobs of air, if you are hearing this sucking sound with the ducting off then I wouldn't be alarmed, and it would not be able to idle correctly since it is not getting any incoming air readings from the MAF sensor. Double check all your ducting once you get everything back together for vacuum leaks, from the TB to the airbox, and set that minumum air and TPS voltage, and see how that works. BTW, why did you take the IAC off and start the car anyway?

------------------
Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

[This message has been edited by Kevin Irving (edited February 24, 2001).]

 

RP, it's very possible you do have a bad IAC, tell ya why...if you're to put power to it with thwe IAC removed from the car, the pintle should extend too far (and fairly quick too) and come out of it's it's seat...and leave you looking for the pintle in the direction you had it pointed , ofcourse *I've* never done this....

But, lets take the IAc out of the equation anyway...reinstall it, and follow the "minimum idle setting" procedure in the Tech Section at www.thirdegn.org,...in you will be extending the IAC valve to the TB seat, then disconnecting the harness...at this point, you'll be blocking off any contolled vacuum leak that the IAC uses to maintain idle RPM's...so at this poinit (IAC extended and unplugged) start the car and see how well the idle is controlled...it's best to do this on a fully warmed up motor.

Now if the engine idles smoothly, the either the IAC is at fault, or another input to the IAC that controls it's setting, is at fault.

If the idle still surges up and down, then the problem lies elsewhere.