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Hey guys, doing some general throttle body work and decided to take a look at the IAC valve. It's very grimy and may not be functioning correctly. My understanding is that it should open with voltage applied. Mine stays stuck, even when I apply full 12 volts. I remember doing this test on my daughter's Civic and 12 volts on/off made the valve cycle correctly.

Do I have a defective/stuck valve or did I do an incorrect test?

Thanks,
BB
 

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To check to IAC, first check for a voltage signal from the PCM. Turn the ignition key on (engine not running) and with a volt meter probe the wires of the terminals on the electrical connector. It should be approximately 10.5v. This will indicate that the IAC is receiving the proper signal from the PCM.

Next, remove the IAC and inspect it. Check for a good gasket and the pintle for excessive carbon deposits. If necessary, clean the pintle with carburator cleaner spray.

Next, check the resistance of the IAC. With the electrical connector disconnected, check resistance between the two IAC terminals, which should be between 7 and 13 ohms.

If you are out of range on any of these tests, replace the IAC. Remember that the IAC valve itself is an electrical component which could become damaged or wear out.


 

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yo,
In addition to what our Resident Brother-in-Wiring and grease Expert advised..
Same 7 and 13 ohms in"

Wiring Diagram, from 95 FORD EVTM Source: by FORD via SeattleFSB (Seattle FSB) at http://www.supermotors.net/registry/20487/76451

Idle Air Control (IAC); also called, Idle Air Bypass (IAB), Idle Speed Control (ISC), Throttle Bypass Air, Idle Bypass, Inlet Air Controller, Inlet Air Bypass, Intake Air Bypass, Intake Air Control
Long Crank Times may be traced to a sticking Idle Air Control (IAC) valve, TSB 97-9-5 for 95-96; "...After a 1-4 hour engine soak time, long crank times and/or long crank to start followed by a stall may occur on some vehicles. No further stalling or rough idle will occur after the engine is running. The long crank and/or stall may be due to the Idle Air Control (IAC) Valve sticking. Replace the AC Valve with a revised AC Valve if no Diagnostic Trouble Codes (DTCs) are present."
Source: by Ford via stangnet.com


also by Steve83 w/ More test info
http://www.supermotors.net/vehicles/registry/media/470492

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Consider Ford Fuel Injection and Electronic Engine Control: How to Understand, Service and Modify, 1988-1993; & Ford Fuel Injection and Electronic Engine Control: How to Understand, Service, and Modify All Ford-Lincoln-Mercury Cars and Light Trucks, 1980 to 1987 by Charlie Probst
Available at Barnes & Noble, E bay, AMAZON, etc.
 

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Hi,

Sorry to ask this here but I don't have enough posts to start my own thread.

I am having a idle issue also. KOEO 111, KOER 111. 91 302 E4OD. The idle air valve is new. Symptoms are slight unsteady idle. Also when the a/c is turned on while idling the idle drops and slowly recovers or dies. If a very slight load is applied (like in gear on slight hill just enough throttle to get the truck to move) the idle cycles up and down a couple hundred rpm.

I will start testing some stuff tonight. Do this sound familiar to anyone?
 

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To clarify, I turned the a/c on after I noticed the other symptoms to add a little load. I believe it works. I'll unplug it for the drive home from work.
 

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No difference with the a/c unplugged.
 

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bizerker,
I had similar symptoms with the TPS (throttle positon sensor) I don't think I had codes from it, but mine had one of the wires bare and corrosion where the wire enters the sensor. I don't remember the exact test procedure, but Haynes manual tells how to test it. If you need it, get back with me and I will try to post it.
 

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Is there a min post count to start a thread??
 

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bizerker,
I had similar symptoms with the TPS (throttle positon sensor) I don't think I had codes from it, but mine had one of the wires bare and corrosion where the wire enters the sensor. I don't remember the exact test procedure, but Haynes manual tells how to test it. If you need it, get back with me and I will try to post it.
I'll check it out. I have a feeling I might have cracked one of the hard plastic vacuum lines that go to the smog pump bypass or diverter. I know I broke one by the relay and patched it with a piece off rubber hose. I just had the upper intake off the change valve cover gaskets and lift the engine to replace 6 block freeze plugs and motor mounts. When I put it all back together it ran weird.

I wonder if I could have crushed the check valve on the MTA EGR tube above the catalytic converter against the firewall when I jacked up the engine. I guess I have some more stuff to look at.
 
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