Fast Idle

darksky47 · #1 (**permalink**) 04-29-08, 10:10 AM

what would make the idle go up and down after my car warms up it used to idle at 800 RPM'S now it jumps to 2300 RPM's for about a 30 sec then back to 800 RPM'S then back to 2300 RPM'S over and over. But it drives great besides that.i for got the CEL came on with the trouble code 0411 i cleared it.
It never came on again but the car is still having the idle trouble. If anyone has had this trouble and fixed it what did you do thanks.

wildrage · #2 (**permalink**) 04-29-08, 11:25 AM

PO411 indicates a problem with the secondary air injection system. I had this problem with one of my mustangs, and more recenlty with my 01 sport after I reversed the vacuum hoses going to the check valve.

I don't know if it would cause a fast idle, but the secondary air injection injects air into the cats to make the O2 sensors run lean, typically at idle. There is a pump for this in the driver's side fender not too far from the radiator drain cock. In addition there is a check valve and air valve in the front driver's engine bay.

darksky47 · #3 (**permalink**) 04-29-08, 09:32 PM

Thanks i will look to see what i can find.