Jeep Zj 5.2 Rough Idle.

TapouT

Well-Known Member
Joined
Oct 5, 2008
Location
Hickory nc
I have a 1998 Jeep Grand Cheorkee with the 5.2...It has sort of a rough idle when in drive sitting at stoplights etc and also when in park. It's not a horrible miss but it's noticeable. I cleaned the stock IAC and throttle body and that didn't help much so I replaced the IAC with an Autozone brand and that helped a little and I also just did a tune up on it with new plugs, wires and dist cap and rotor button and that helped a little more but the idle still fluctuates when in drive and park. It will bounce between 500-700 rpms and just go back and forth and vibrates a little. What else could it be?
 
Monitor your throttle position sensor voltage at idle. It should remain constant and not flunctuate at all. Measure that and report back. A faulty TPS can definately cause idle issues.
3 wires at the TPS- 1 is 5 volts, one is ground, you want to probe the other one. Your reading should be somewhere around .7 volts or so.
 
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