It happened so suddenly. It was friday night while cruising that I noticed my 03 Mustang GT started to hang on the idle at 1400 rpm for a long period of time, and would only go back down once I stopped and sat for awhile. First thing I though was the IAC, so I replaced that and no avail. Then I cleaned the MAF, and throttle body really well. Still, nothing. I had it hooked up to the scan tool tonight and while in the Idle Speed test mode, I can manually adjust the IAC, and it behaves as it should when I change the %. It idles really well at 50%, and also comes right back down to idle when it is kept at 50%. Once I exit that troubleshoot mode, the hanging idle comes right back, and the values of the IAC come down quite slowly from a rev along with the rpms. I am at my wits end here. Also, at idle, my TPS value is at .98 volts. I think that is right where it should be.
My mods are: Accufab Throttle body and Plenum, BBK cold air intake, full exhaust, H-Pipe, Flowmaster after the H-Pipe, and an SCT Eliminator Chip with unknown tunes on it from the previous owner.
Here is a video of it running with the IAC Value set at 50%
And here is a video of me driving. I take foot off the footfeet, push the clutch in, and coast to a stop. You notice it hangs for quite awhile, then drops down to below idle range before catching up to where it should be.\
My mods are: Accufab Throttle body and Plenum, BBK cold air intake, full exhaust, H-Pipe, Flowmaster after the H-Pipe, and an SCT Eliminator Chip with unknown tunes on it from the previous owner.
Here is a video of it running with the IAC Value set at 50%
And here is a video of me driving. I take foot off the footfeet, push the clutch in, and coast to a stop. You notice it hangs for quite awhile, then drops down to below idle range before catching up to where it should be.\