In addition to previous posters suggestions, double check and make sure that u purchased and installed the correct IAC for your specific model, year, etc. It's not likely that an incorrect IAC would have the same connections but I've seen it happen and the problem really sounds like your IAC. Also take a look @ your Mass Air Flow sensor. Usually a bad MAF would just cause the car to stall but a dirty one might cause it to freak out. Lastly, you may have a bad fuel pressure regulator. You can check it by attaching a fuel pressure gauge to the schrader valve on the fuel rail and turn the ignition w/o cranking the engine. Your psi should be about 40-43 psi. If it's higher it could be your FPR letting the fuel pump go nuts, hence the high idle.
Friday, June 13th, 2008 AT 3:56 AM