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quzzeeq
quzzeeq 7/11/2010
1992 Ford Bronco XLT 8Cyl5.8L - Engine
Any ideas on how to trouble shoot Idle issues?
My Bronco has always had A high idle, but about two months ago my rear abs light came on and my idle was going haywire and the truck felt like it was going to die at any minute but yet the idle was all over the place. I replaced the speed sensor and it seemed to take care of the problem until I drove a long distance and it has started all over again but worse if I shift into N the rpms go up as high as 3000 then R about 1500 and P the same as N but even higher at times . Any one? Any ideas?
Foot note I did take it to a repair shop at my witts end and of course it would not act up then or on the test drive, he could not find any thing wrong except my throttle body is worn. Could he be telling the truth? No codes came up on the obd2 Im leary of his solution he charged me 90 bucks and said sorry its a discontinued part and sent me on my way. HELP??
5 Answers
  • JunkFixer
    JunkFixer 7/11/2010
    This sounds like a gnd issue. Voltage drop testing of the engine and PCM gnds would be a good place to begin.

    Yes, he could be telling you the truth. A repair kit is available for these old throttle bodies but they are not easy to install. Often, machining is req'd.
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  • JunkFixer
    JunkFixer 7/11/2010
    You sound like you're smart enough to remember the KISS principle (Keep It Simple, Stupid). It's far too easy to outsmart ourselves when going after a problem whose cause is not readily apparent. If you need some direction on performing voltage drop tests or specific gnd locations, just ask. Lets begin by using Occam's Razor, not Occam's toolbox. I'll help ya.

    http://en.wikipedia.org/wiki/Occam's_razor
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  • HouseCallAuto
    HouseCallAuto 7/11/2010
    If you have not yet replaced the throttle position sensor and / or the idle air control, that should be done as it is likely for one of them to be the cause of your high idle. The TPS fails on EVERY 5.8 eventually and there are not always codes set. Same with the IAC.
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  • quzzeeq
    quzzeeq 7/11/2010
    Thank you for taking the time to help, I have found a few places that sell after market throttle bodies as well as one that refirbushies them and tacks on a 3 year w. But I really dont want to have to replace it if I dont have to, I am sure I could do it after all I maybe a girl but I have only owened fords and have mostly done all the fixens for all of them except the heavy duty stuff of course. I will start with your suggestion first thank you. I keep ya posted.
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  • quzzeeq
    quzzeeq 7/12/2010
    Yeah its all better now I think! So Far so good. And yes it was the IAC. I tested it before I bought it on-a-count-of it was a 75.00 part. Like I said all is well for now thank you for all the help everyone.!
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