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Guys -

Did a quick search, came up with not much helpful.

My 90 XLT Bronco (351W/auto) idles at about 500 RPM, maybe a bit lower. I would like to bring the idle up to about 7-800 RPM. Sorry for the stupid question, but how do I do that on this truck? Is it a "mechanical" fix (i.e. turn a screw), or does it involve something with the computer?

thanks

nate
 

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The Anti Yam!
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Gacknar said:
If the idle is that low then there is somthing wrong.

Check the voltage on your TPS.
http://fordfuelinjection.com/index.php?p=30

Disconnect the IAC when running, the RPMs should drop. If not you may need a new one.
http://fordfuelinjection.com/index.php?p=39

Check for codes.
http://fordfuelinjection.com/?p=13
Not to hijack, but.........Gacknar are you saying that if I unplug the IAC while the truck is running the RPM should just drop, or should the engine stall out???
 

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The Anti Yam!
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Streetgang said:
Not to hijack, but.........Gacknar are you saying that if I unplug the IAC while the truck is running the RPM should just drop, or should the engine stall out???
Idealy it should drop to 450-400 rpm, but most older engines have trouble running that low so it will probably stall.

Basicly if you unplug the IAC the idle should drop
(if the idle set screw has not been tampered with and there are no other high idle problems like a vaccume leak)
weather they drop to 450 rpm or 0 is of no real consiquince.

The thread starter has a low idle problem, if the TPS is reading correctly and the IAC is functioning properly then when he disconnects the IAC the idle should drop even more. If not then the problem could be a bad IAC
 

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Lick my balls
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Gacknar said:
Idealy it should drop to 450-400 rpm, but most older engines have trouble running that low so it will probably stall.
Basicly if you unplug the IAC the idle should drop
(if the idle set screw has not been tampered with and there are no other high idle problems like a vaccume leak)
weather they drop to 450 rpm or 0 is of no real consiquince.

The thread starter has a low idle problem, if the TPS is reading correctly and the IAC is functioning properly then when he disconnects the IAC the idle should drop even more. If not then the problem could be a bad IAC
Just a tidbit of info some people might find interesting, I have a 55 buick century and the shop manual says to set the idle to 450 RPM. But that is not the most interesting part. The part that gets me is that the manual wants me to turn the idle down to 350 in order to set the timing. The reason for this is that the centrifugal thingy in the distributor doesn't operate at that low of an RPM. That makes sense accept that I've never owned a vehicle that could run at such a low RPM before, and this one does...barely. I was thinking, if your motor is so out of whack that you can't run it below 550, for example, there is no way to accurately set your timing. Also, for those of you who think that it was a low compression or W.H.Y. the motor is a 322 CID and in 1955 it came from the factory with 235 horses, the most horsepower available at the time.

Interesting, huh?
 

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Lick my balls
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Gacknar said:
Interesting yes....


But pointless :goodfinge :toothless
:histerica :histerica :histerica not quite the response I expected.
 

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Lick my balls
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Gacknar said:
What did you expexct? :toothless
OOOOOOOOOOOOOOOOOO, AAAAAAAAAAAAAAAAAAAAAh, that was very fascinating, tell us more.
Something like that. The main point was the 350 RPM, I never heard of such a low idle. Heck, I didn't even know a V8 could idle that low... now go away :goodfinge
 

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Does Ford use a stepper motor for IAC?

Stepper motors use two sets of brushes to turn the motor in quarter turn increments. When u unplug the motor will dictate where it idles.

Turn on the a/c and the IAC will open up, unplug the IAC and idle will stay higher.

Try tearing an old IAC apart and making one u set manually and lock with a jamnut.

If your running (idling) to high, make some jumpers and attach them to the batt. touch them to the terminals on the motor alternating between poles. naturaly -/+ polarity will dictate what direction the motor turns.

a wiring diagram would tell you what terminals are paired.

If ford uses a staight up motor and position sensor none of this applies.

Hope this might help.:toothless :rockon
 
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