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post #1 of (permalink) Old 02-28-2000, 08:58 AM
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High RPMs in Park


Just in these past couple of months, I have noticed that my whenever my Bronco is in park or neutral, it runs at around 1200 RPMs, no matter whether the engine is cold or warm. In drive and all other gears, it is consistent at 900 RPMs. The thing that worries me is the horrible chunk the transmission makes each time I shift between drive and park/neutral and vice versa. It is especially bad when I am in a parking lot, and I shift from drive (900 RPM) through Neutral (1200 RPM) to Reverse (900 RPM), and back. I am not sure whether this is normal but it sure is annoying. I think there is a problem with the engine as opposed to the transmission, but that is just my opinion. Any input is greatly appreciated. Thanks

1992 FS Bronco 302
E40D transmission (ATF changed less than 6000 miles ago)

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post #2 of (permalink) Old 02-28-2000, 12:31 PM
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Re: High RPMs in Park

Agree, your high idle speed is probably whacking that trans pretty good.
Have you tried taking off the IAC (Idle Air Control) motor and cleaning it out, along with the mating holes in the Throttle Body?
If you haven't, that's where I'd start. BTW, if your IAC is integral valve/motor (motor housing crimped over the Aluminum valve body), then be carefull when using Gumout or other solvent not to get it up the shaft into the motor. Keep the valve end down when cleaning, so that doesn't happen. On some of the older ones you can pull 2 screws and separate the motor from the valve body, but I think yours may be too new for that.
The cleaning is simple to do if you haven't done it already, and the gasket usually stays on the Throttle Body, so just put it back on after cleaning.
May or may not be your problem, but its an easy and common place to start.

post #3 of (permalink) Old 02-28-2000, 01:27 PM
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Re: High RPMs in Park

I'd first make sure the usual tune-up stuff is in order(timing)and check for vacuum leaks. My 86 was doing this and I found a small vacuum hose knocked off at the plenum chamber. Or, could be a stuck Idle Air Control valve too.

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post #4 of (permalink) Old 02-28-2000, 06:11 PM
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Re: High RPMs in Park

Thanks for the input - I just parked my car at work today and it was at 1400 RPMs in park.... doh!

post #5 of (permalink) Old 03-01-2000, 12:31 AM
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Re: High RPMs in Park

btw, 900 in drive is high. I think the specs call for 600 - 100. At least for the F.I. 302 engine with AOD. Mine idles at just about 600 in drive.

post #6 of (permalink) Old 03-06-2000, 01:44 PM
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Re: High RPMs in Park

I'm not familar with your year motor/injection set up....but do you hear a noise when you turn off the motor? .....from under the hood I mean? On my 86 Tempo (since retired) I had the same symptoms.....the idle speed motor (what ever the real name is for it) had siezed. I pulled it apart and the gears had blown apart. When ever I turned off the engine the idle speed thingie would go to the "off" position....then it stopped. Actually when I started it up the thing was constantly trying to adjust the idle but since nothing was moving the little motor was wailin' away to no end.....but I could not hear it because of the running engine.

Just a thought


Figures don't lie ....... but liars sure do figure.
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