I just recently built a 383cu. and I am having trouble with the idle. I took it to G-FORCR MOTORSPORTS in Houston and put it on the LT1 EDIT. They changed two rear sensors, and programmed it. The car is still idling at 1400 rpms and won't come down. I can go outside right now and crank the car and it will sound great and idle at 900rpm for about 10 seconds. Then it idles up to 1400 and stays there. WHAT IS GOING ON? Please take time to give me some suggestions. They will greatly be appreciated. Race season is in 4 weeks! This is a new thing for me, I'm used to the carburated thing....lol.

Matt

 

Some helpful info would include the basics, like the year of your car and the extent of the modifications.

What do you mean by "They changed two rear sensors"? Do you mean they programmed out the after-cat O2 sensors used on the OBD-II cars?

Sounds like you may have the throttle stop screw out to far, preventing the IAC motor from controlling the idle speed. Do you have any idea what they set the idle speed at when they programmed it?

The more info you can provide about the car and engine, the better chance you have of getting a good response.