bronco high idle and truns off when lowered - Ford Bronco Forum
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post #1 of 8 (permalink) Old 11-01-2012, 10:59 AM Thread Starter
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bronco high idle and truns off when lowered

hi guys i have a 1991 bronco when i bought it it would turn off the second u put in drive or reverse,so i put new plugs,wires,oil,fuel filter ,air filter,ignition coil,idle control valve,and new distributor now the truck drives and has no problem going into gear but the rpm's are at 1500 on idle but when we lower the idle she dies in gear like right away i am at whits end i just bought a scanner and am gonna try when it get to house but i also thought i could have a vac leak but i cant seem to find any
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post #2 of 8 (permalink) Old 11-01-2012, 11:04 AM
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Come back with the codes then will talk

1992 Bronco XLT, 351w. 8 inch lift SAS on tons!
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post #3 of 8 (permalink) Old 11-01-2012, 11:32 AM Thread Starter
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ill give it a try will see what the hell happens this truck loves to kick my ass lol
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post #4 of 8 (permalink) Old 11-01-2012, 01:03 PM
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Definately pull codes and see what elec/electronic faults are indicated but usually cleaning the IAC = idle air control valve does the trick, check test the TPS = throttle position sensor for voltage range, either may pop up as a fauilt code.

Just press the gas pedal down when the idle is high and kick the rpms down until you figure it out.....with sensors a lot depends on how old they are so if you don't know or haven't replaced in some time them now is a good time to do so....

The rule of thumb with the IAC is, if you unplug it and the engine stalls it's one full turn of the throttle body "idle stop screw" inward/right located on the right side of the throttle body, it's spring loaded and I would count the number of screw threads protuding on either side of the TB block if you need to put it back the way it was....

Good Luck ~
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post #5 of 8 (permalink) Old 11-01-2012, 07:41 PM Thread Starter
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thanks JKossarides ill post what codes the scanner post
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post #6 of 8 (permalink) Old 11-21-2012, 08:08 AM
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Any update on this one? There are a couple of threads on it but never heard if you figured it out? I have the same issue.
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post #7 of 8 (permalink) Old 11-21-2012, 10:06 AM
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Originally Posted by Big Chief View Post
Any update on this one?
I have the same issue.
Rex/OP lists everything except a new TPS (reporter). ;)

Been thinking about how to go about getting a "TPS report" and just now
came up with this idea... Strip the three wires (or just two) like a 1/2"
and then twist the wire to form a "teat" then solder the little teats.

The trick is to stagger 'em so they won't-never touch each other.

I made three little jumpers but it's just another step installing those that
just seems unneeded?

Test yours using an analog voltmeter and/or an ohmmeter, look for smooth
voltage or resistance operation. It's a potentiometer... is there such a thing
as a 100% all-the-time -smooth- operating potentiometer? LOL :)

Alvin in AZ
ps- Just checked out and a Standard Motor Products TPS
is more money than a Motorcraft. ~$50 ...look under "Fuel/Air"
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post #8 of 8 (permalink) Old 11-21-2012, 03:34 PM
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Junkyard made TPS Test Harness...

My concern is how the OP is lowering his idle which caused the engine to die in gear. I hope he wasn't turning the factory set throttle stop screw...

See these links:

Throttle Position Sensor Testing, Replacement and Adjustment

How to Test and Clean your IAC
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