Questions and Answers

Ford Bronco Idle Sticking Too High Q. My 1995 Ford Bronco, 5.8 liter EFI 117,000 miles, P/S, A/C and cruise control, is idling to fast, about 1,200 rpm. I can kick the throttle and make it come down but all I'm doing is making the butterfly valves in the throttle body jam shut. There is still vacuum in the throttle body trying to open the butterfly valves.

So when I step on the gas and let off normally, the vacuum holds the butterfly valves open just enough to make it idle high. When I disconnect the idle air control valve it idles fine, about 700 rpm. I've replaced the idle air control valve and sensor twice. So I know they are okay.

So for some reason the CPU is telling the idle air control valve to create too much vacuum in the throttle body. Weird thing is when I start it, it idles high for 20 seconds then idles down on it's own to where it should be. Vary little vacuum in the throttle body. But as soon as I step on the gas pedal, the vacuum goes up and stays there.

It's kind of hard to hold her back at stoplights, keeps wanting to climb up onto the car in front of me. Well, any suggestions would be helpful!

Thanks,
Jim

A. The first thing to do is check the PCM for any codes. That will help by giving us a starting point for troubleshooting. Lacking any codes, you will need to go through a rather lengthy diagnostic procedure to pin point the problem.

Your best bet is to go to the local Public Library and in the reference section get the Motors manual for your vehicle. It will have the procedure and diagrams you will need to troubleshoot this problem.