My wife has a 99 Jeep Grand cherokee and it will not idle, you have to keep your foot on the gas. We noticed it was having a batterie prob, and got it fixed, and now it acts funny trying to start, and like I said it will not idle. Could it be a TPS (Throttle Position Sensor). ?? I dont know sh!t about jeeps

Probably a bad or unlearned IAC(Idle Air Control Valve). Try turning the key to run and not starting for 30 seconds or so. Then shut off and start the vehicle. If that doesn't work remove the IAC, on the throttle body, adn see if it is extended. If so, compress it and reinstall without hooking up the electrical connector and start. If it will idle its probably a faulty IAC

Originally posted by biggnome
Probably a bad or unlearned IAC(Idle Air Control Valve). Try turning the key to run and not starting for 30 seconds or so. Then shut off and start the vehicle. If that doesn't work remove the IAC, on the throttle body, adn see if it is extended. If so, compress it and reinstall without hooking up the electrical connector and start. If it will idle its probably a faulty IAC

I was doing a little reading, and stupid me didn't even think of it, but I pulled the + side cable off for a min. and hooked it all back up, and it seems to be doing fine. What could of caused that?

Originally posted by .oHARLEYo.


What could of caused that?

When I first got my '99 GC (used) I did a lot of reading on the web about it. I don't know what could have been the original cause of your prob but IIRC there are A LOT of electronics in this beast. The computer "learns" your driving patterns, after a reboot (i.e. removing the battery cable like you did). The learning supposedly improves shift points, etc. I haven't really played with mine cause it's seemed fine to me.:rolleyes:

It did that to ours also, when you pull the neg - it resets the computer mod. back to normal codes.