3.0 1998 ranger high idle

[dmb2613]

My ranger was giving me fits with the run away idle [ 3,000 rpm or more[ I put several iac valves on it the last one OEM ford. Well I fixed it by accident. Put a new ALT on it . Runs better than it ever did

 

[xeris]

I had the same issue. A couple of years ago, somewhere deep on the internet I found a thread, maybe here, that explained the problem. The computer sees voltage from the alternator below a set point and increases the idle to raise the voltage. After I read that I checked the voltage at idle and it was a bit low. Installed a new alternator, problem solved.

 

[Stankard757]

Glad I found this May have solved my problem. Thanks