4.0 Idle too fast

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Nov 17, 2004 | 08:57 AM

gtsmk

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4.0 Idle too fast

Have '93 Explorer w/4.0 V6 that idles too fast. Starts and revs to 2000 rpm and stays there. Had the control module on top of the air intake changed, and it still runs too fast. When this is unhooked, by simply unplugging the wire, it idles down too low, at about 500 rpm. Is there an adjustment in the system that can be easily done by a novice, or is it controlled electronically? Would like to avoid the garage, if possible. The module cost me nearly 90 bucks, and I need to know if that is the problem again. Any help is appreciated!!

gtsmk

Nov 17, 2004 | 10:50 AM

mrshorty

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From: UT

Any vacuum leaks will cause the engine to idle too fast.

Run the EEC-IV self-tests. The computer does some simple checks of the IAC valve.

Nov 17, 2004 | 03:35 PM

gtsmk

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Can you explain that a little bit better? You are dealing with a real rookie here, but he does want to get better. I haven't run any of these tests in the past, and know nothing about that. Thanks for helping a dummy!

Nov 17, 2004 | 04:57 PM

mrshorty

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Instructions for EEC-IV self-tests (aka pulling codes) can be had under "tests" at www.dalidesign.com/hbook/eectest.html

Nov 28, 2004 | 10:34 PM

daerhldgs2

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sounds as though your Idle Air Control (IAC) is malfunctioning. Go to a wrecker preferrably self-serve and get a few - each will give slightly different results.

Nov 29, 2004 | 11:22 AM

Rockledge

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From: Connecticut

Quote:

Originally Posted by daerhldgs2

sounds as though your Idle Air Control (IAC) is malfunctioning. Go to a wrecker preferrably self-serve and get a few - each will give slightly different results.

That's probably the "control module on top of the air intake" that he referred to and has already replaced.

I agree, sounds like an possible air leak somewhere. Check all the vacuum hoses and connections, look for possible sources where air is being pulled into the engine. And follow the instructions vis a vis the link and retrieve any trouble codes from the computer.

Nov 30, 2004 | 07:23 AM

gtsmk

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Found the problem. A vacuum line had come off up behind the air intake. Made quite a difference, but still idles a bit fast, at about 1200 rpm, but it was at about 2000 rpm, so that is much better. Is there any adjustment screws for the idle?