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Unread 08-18-2013, 11:43 PM   #1
Bryan2269
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1998 ZJ 
 
Join Date: Dec 2010
Location: Lewiston, Idaho
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idle issues

Hey guys so I have been having a weird occurrence with my idle when I switch it to park. It started about a month ago randomly after driving back from work, when I put it into neutral or park the rpm's would go all the way to 1,000-1,250 rpm and it used to regularly stay at around a consistent 500. Anyways, I didn't think much of it the first time just thought it was a glitch of some sort. The next week it did it again just randomly; now its to the point that it's occurring a lot more frequently and only does it when it's engaged into park or neutral. Is it a choke issue, idle sensor, what could it be? Help will be much appreciated to solve this problem!!

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Unread 08-19-2013, 06:55 PM   #2
ZeeJay1997
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clean IAC and check for vacuum leaks
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Unread 08-20-2013, 10:11 AM   #3
dougmorgan99
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1998 ZJ 
 
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Quote:
Originally Posted by Bryan2269 View Post
Hey guys so I have been having a weird occurrence with my idle when I switch it to park. It started about a month ago randomly after driving back from work, when I put it into neutral or park the rpm's would go all the way to 1,000-1,250 rpm and it used to regularly stay at around a consistent 500. Anyways, I didn't think much of it the first time just thought it was a glitch of some sort. The next week it did it again just randomly; now its to the point that it's occurring a lot more frequently and only does it when it's engaged into park or neutral. Is it a choke issue, idle sensor, what could it be? Help will be much appreciated to solve this problem!!
Good luck. I've been trying to hunt down my erratic idle issues for over a year. I cleaned and then replaced the IAC, O2 sensors, checked for vacuum leaks and replaced TPS. I am going to replace the MAP next then I will start looking at the PCM harness pins. Shaking and pulling the PCM harness changes nothing to the idle so I think its fine, but you never know. I may have bad solder points in the PDC itself but I am saving that as the final thing to touch. I am fustrated like many folks her trying to track it down since it is an erratic issue. Just when I find time to try and work on it. The Jeep behaves... OH! I just remember I may do the Ambient Air Sensor next since that controls timing. May go ahead and do the mod since I have a FIPK to get a minor performance gain... (pipe dream some say). Either way, post if/when you figure it out.
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Unread 08-20-2013, 07:02 PM   #4
ZeeJay1997
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Originally Posted by dougmorgan99 View Post
I may have bad solder points in the PDC itself but I am saving that as the final thing to touch.
No solder joints in PDC. It does have blade connectors on bottom.

It's never hurts to clean the connections on the PCM. The IAC runs on 4 signals that vary from 0 to 4 volts so it doesn't take a lot to throw a wrench in the monkey works.
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Unread 08-21-2013, 10:29 PM   #5
dougmorgan99
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1998 ZJ 
 
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Thanks ZeeJay, I have no idea what a PDC is or why I typed that. I meant PCM. I was referencing a write up to take the PCM apart to resolder joints/points on the actual board versus soldering anything on the harness.

http://www.jeepforum.com/forum/f13/9...tures-1303589/
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Unread 08-22-2013, 05:36 AM   #6
ZeeJay1997
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Quote:
Originally Posted by dougmorgan99 View Post
Thanks ZeeJay, I have no idea what a PDC is or why I typed that. I meant PCM. I was referencing a write up to take the PCM apart to resolder joints/points on the actual board versus soldering anything on the harness.
The PDC is the fusebox under the hood. If you havent done so already, take everything in there out and clean it. This should be routine maintenance.
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Unread 09-02-2013, 01:51 AM   #7
Bryan2269
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1998 ZJ 
 
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Hey, sorry guys it took me awhile to respond back to you engineering was sucking my life away. Anyways to the point I cleaned all the sensors on the throttle body I got the 5.2L by the way. The MAP was gunked up with a black film that was expected since that hasn't been clean for 200 plus thousand miles, used MAF cleaner and some scotch bright and worked wonders. I should of cleaned the throttle body itself to just for added measure but, that will be done soon. In addition I cleaned all the electrical connectors and applied dielectric grease for extra security. My idle problems are no more and throttle response is better. I knew the it wasn't my PCM since, I replaced that about 5 months ago from another ZJ with considerably less miles. Anyways hope that helps and thanks for the help guys really do appreciate it!
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Unread 09-02-2013, 09:41 AM   #8
dougmorgan99
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1998 ZJ 
 
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Awesome, as a stated my MAP sensor in next to replace or clean. Maybe I'll be motivate this weekend to do it since you was successful in banishing your idle demons... Thanks for let in us know!
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