I have a 383 in with a fairly hot cam. I can’t seem to turn the idle down. Fallowing the procedure for adjusting the idle, I have backed the throttle screw out all the way. I still idle at about 1800 in park /neutral and 1200 in gear. Is this a sign of a bad IAC valve?

Any ideas or suggestions are greatly appreciated.

Could this be a chip programming issue? I did have one burned for my cam and injectors.

Thanks,
Jim

 

Alright, seriously guys come on. Some must have run into this issue before. I've tried adjusting IAC to no avail. I'm not recieving any error codes. How can a trim down the idle to a more respectable rpm?

Even if you don't know, just shot out ideas so I can continue with a more guided work.

Thanks,
Jim

 

At least specify the induction...

BTW, which cam do you have and have you had the PROM tuned for it?

 

we need more info about your combo, but youve got more air entering the engine than you suspect and leaking or non-sealed intake gaskets,throttle body gaskets and vacuum leaks or disconected vacuum hoses are major suspected sources for that extra airflow
while the IAC may be bad its easy to check and ID seriously doubt that alone would allow a 1800rpm idle speed

 

yeah, sounds like a vacuum problem to me, hook up a vacuum gauge

if its an improperly tuned ECM, maybe the computer is telling the injectors to give too much fuel

 

Hello everyone,

Thank you greatly for the feed back. Your right, specs would prove to be most helpful; please see below.

Engine Make: 383 SBC, 10.5:1;
Heads: Trick Flow 23° aluminum, 195cc, 2.02” In. 1.60” Ex;
Camshaft: Cran Cam Partr # 08-503-8, Grind # XR276HR-12, 108°, Duration @0.05 224 In. 230 Ex., Lobe Sep. 112;
TPI: AS&M LTR, Accel manifold;
Exhaust: SLP headers, 3” cat-back;
Misc.: 3.23 rear end, 30 lbs/hr EV1-Type injectors, pro-built 700R4 w/ 2000 stall converter, custom chip for cam

From what I gather, it is either a ecm-chip issue which would be resolved when I get the car tuned, or I have a leak (which I also suspect because I hear it when the car warms up). How do I locate a leak because I have been un-able to do so by sound?

Thank again for all the help.

 

yeah the way I find vacuum leaks is clean and easy with no mess. get a propane torch,


(DONT LIGHT IT) just SLIGHTLY open the valve so its allowing gas to flow at a low voluum,start the engine and let it idle at the lowest speed you can then place the tip of the UNLIT torch at any suspected vacuum leak and listen for the rpms to increase , and watch the tach, gas flowing into a vacuum leak will increase engine speed. and wont make a mess or harm anything

 

I appreciate the responces. Hopefully if I have a vacuum leak I be able to find and fix. Aside from that, I guess I would just be surprised if a small leak could pull that much air to increase rpm. I will just have to check everything from the intake manifold on up huh?

Any other thoughts?

Thanks again guys.

 

if you have any kind of leak wont you need to replace the intake gasket no matter what?