Idleing problems

[guy who loves fords]

Hello everyone.I'm the proud owner of a black 1993 Ford Bronco Eddie Bauer with a 5.8L 351 Windsor. Recently, the truck cut off in the driveway as I was backing out and would not start back up. It was diagnosed to be the computer, or PCM or ECM or whatever it is called, it's on the firewall...anyway it was diagnosed to be that so a new one that had already been programmed was ordered and installed by a professional. Now, it does start up but it idles to high. I would understand this idle speed if the engine was cold which is around 1200 rpms, but even after it warms up, it still woon't idle down, even after driving it and bringing the engine to 4800 rpms just to see if that would help, it still won't idle down. Let me note that this is the 3RD computer to be put in the truck. The first one they sent did not fix the problem, so they sent another one and it didn't fix the problem either, so I got on the phone with them to explain what was going on and the guy insured me that he would program it himself personally, and that it would fix the problem when we install it. It did fix the problem but now it isn't idleing right. I'm sort of convinced that it isn't a problem with the computer, but if it is I do have a buddy who has a shop that has a high tech scan tool that could possibly help me. If anyone on here could help me please, i'd be a big help.

 

[miesk5]

yo guy who loves fords,

WELCOME!

I like the idea that you have a buddy who has a shop that has a high tech scan tool!!!

That will help immensely for electrical issues such as from slightly dislodaged connectors, damaged/ corroded terminals with connectors, "Terminal backout" with connectors to bas sensors, grounds, etc.

or, Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to:

KOEO

&

KOER

Joe also placed a vacuum leak test in there that is often cited by Ford in a diagnostic process.

---

One Guess is the 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

see Overviews, Tests, etc in my site @ http://www.broncolinks.com/index.php?index=397



Location pic by SeattleFSB

& by Steve

Testing & Replacement; Make sure the ignition key is OFF . Disconnect the air control valve. Use an ohmmeter to measure the resistance between the terminals of the valve solenoid. Due to the diode in the solenoid, place the ohmmeter positive lead on the vehicle power (VPWR) pin and the negative lead on the ISC pin. If the resistance is not 7-13 ohms replace the air control valve.

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 Charles Probst

avail @ BARNES & NOBLE, AMAZON, E BAY, ETC.