A Ford Forgets How to Idle
courtesy of Bob, The Auto Answer Man
I hope you can help. I have a 97 Ford Explorer. It starts up ok when cold. After the engine gets hot (20 to 60 miles) the problems start.
It will idle very slow, stall after a few minutes at idle either in park or drive. It shows low RPM's and low battery. If you press on the gas pedal everything rights itself. The idle goes up and RPM's go up and the battery gage goes up. Until you let off the gas or stop at the next red light. It is an intermittent problem that is getting worse. If you get out onto an open road with no stop lights it gets better temporarily.
So far, we have had the fuel filter changed, the fuel injectors cleaned, 2 EGV valves cleaned and 2 changed, a loose connection on the mass air flow fixed and a vacuum hose reattached. We have also had the alternator checked. It was fine. The battery is borderline but we have been told it would not cause the problems we have. Please help if you can
Sounds like your car forgot how to idle or the idle air control valve is not functioning correctly. On a warm day do this, warm the car up for a while, take it for a short drive whatever. When you get home, disconnect the battery and let is sit for about 15 to 20 minutes. Then reconnect the battery and start. Do not touch the gas at all!
This will prompt the computer to relearn how to idle. Let it sit for a while, say 10 to 15 minutes. You may see it hunt for a little while. If this does not fix the problem, then it may be the air valve or it could be your fuel pressure regulator. On Ford trucks, they are known to fail in a high pressure mode. This would make the car confused. It knows how much fuel is supposed to be there, but there is more coming in due to the high pressure. Give this a try and let me know what happens.
Bob, The Auto Answer Man