Mechanics

IDLE PROBLEM

1998 Ford Explorer • 129,000 miles

I have the 4.0L OHV, it won't idle when its very hot, usually upper 80's or above, if I gas it to keep the idle higher it will stay running, but if I let off the gas it will die. This has been happening for two years, and always corrects itself when the outside air temperature decreases. I've replaced wires/plugs, and cleaned both the throttle body and IAC Valve.
Avatar
Coasty
June 21, 2012.




Check engine light on?

Docfixit
Jun 21, 2012.
Just as I hit enter I realized I forgot to say. No, absolutely no trouble codes.

Tiny
Coasty
Jun 21, 2012.
O.K. Lets do a few tests note FORDS VERY common problem IAC
Will it idle when engine cold? If yes then start turn on AC and/or turn steering wheel idles speed increase? Unplug IAC idle fall stall?

Docfixit
Jun 21, 2012.
No, it will not die when the engine is cold. In fact, the only months it's happened over the last few years are July and August when the temps are in the upper 80's.
AD

Tiny
Coasty
Jun 21, 2012.
What is eight character in VIN? IAC is comanded by PCM to maintain idle whatever Temp is and with nothing to go on IAC replacement seems way to go. What ois idle speed whenit idles? Does it responed to AC on and steering?

Docfixit
Jun 21, 2012.
8th Character is "X". It normally idles around 800rpm, when its happening it will drop off straight to about 150-200rpm and then die as fast as you let up on the pedal. I'll have to check the AC/Steering test next time its hot enough.

Tiny
Coasty
Jun 21, 2012.
Fuel pressure 35-40psi? Have used fuel cleaner or upper engine cleaner? Fuel filter less than 15K miles?

Docfixit
Jun 21, 2012.
I just reread your question. Yes it idles fine when it's cold. I thought you asked if it "died" when it's cold, not "idled". I'll check if idle changes with AC and steering movement tomorrow.

Tiny
Coasty
Jun 22, 2012.
When cold: turning on AC/moving steering drops rpms slightly, they do not increase. Unplugging the IAC valve plug drops the rpm to about 150-200rpm, but it didn't die.

Tiny
Coasty
Jun 22, 2012.
Think IAC is in order

Docfixit
Jun 22, 2012.

AD