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djl7780 04-15-2010 06:50 PM

Strange Rough Idle
Hello all,
I have searched the rough idle threads high and low followed the advice others gave, as mine started rough idling yesterday. So rough it shakes and chugs. I cleaned the IAC (which was pretty clean, but I cleaned it anyway) The TPS is new as the person I bought the jeep from a few months ago replaced it. I also cleaned the throttle body real well. The weird thing is, if at idle I turn on the AC, it smoothes out nicely. Turn AC off and back to idling rough. Any suggestions?

AzTJ 04-15-2010 06:57 PM

Sounds like a vacuum problem then. Check and make sure all the hoses are on and tight and not split. Don't know what year your Jeep is, but check the MAP sensor as well (if you have one).

djl7780 04-15-2010 06:58 PM

Forgot to mention it's a 98 TJ 4 banger, manual tranny. Also I did a tuneup last month, new champion plugs, wires, distributor, rotor, and both 02 Sensors. It ran fine after the tuneup (although it is a second vehicle, so it does not get driven much). Seems to just started idling rough

AzTJ 04-15-2010 07:02 PM

Check the MAP sensor (on the firewall) has a vacuum line going to it and a 3-wire plug. Make sure it's on and clear. Check other vacuum hoses too.

djl7780 04-15-2010 07:08 PM

My MAP sensor is on the side of the throttle body itself. The connector is connected.

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