idle problems

[odjeep]

My buddy has a '99 cherokee with the 4.0 and the aux engine fan wont shut off. It stayed on for like 20 min after shut down before we intervened.
I unhooked the fan to shut it off. Could this be a thermostat sensor or something? Also it is having a hard time idling. Think maybe a fuel problem. What do you guys think?

od

 

[XJNick]

Hi,

The fan relay is most likely stuck on. You can tap it lightly with a hammer as a temporary fix, but it'll get stuck again. I'm not sure where the relay is on the '99 models.

As for Idleing problems, the first thing you should do is clean the Throttle Body and Idle Air Control (IAC) motor passageways with carb cleaner. If that doesn't fix it, test the Throttle Position Sensor (TPS) for proper operation, and be sure you have no vacuum leaks.

-Nick :!: