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Unread 04-28-2013, 12:00 PM   #1
Ravie
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1999 WJ 
 
Join Date: Jul 2011
Location: Topeka, KS
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High idle now? Where did THAT come from?

So, if any of you followed my other thread about what turned out to be a crappy jet chip, this is somewhat a continuation but new issues.

So, now that the Jet chip is out, everything is working fine EXCEPT high idle.

Start the Jeep: 2000rpm instantly
Move shift lever into drive: down to about 750rpm
Drive for a little while and put it in park: Still idling at about 1300 after it settles down.

I removed the IAC and the TPS and cleaned them last night (just shot the TPS with electronic contact cleaner hoping some would make it inside) and put them back in and it made essentially zero difference.

So, WTF, did my IAC just crap the bed?

If that's the consensus I'll go ahead and order one, I just want to be sure that's what it is first.

I'm getting no codes.

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1999 WJ - Over 10k on the 4.0 rebuild. FB/BDS 2" lift (2.5") w/Bilstein 5125's. General Class Ham...KC0LUA
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Unread 04-28-2013, 12:11 PM   #2
WJHahn
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W/O reading your other thread, high idle can often be attributed to a vacuum leak. Check the PCV hose on the back of the intake as mine came off and I had the same issue in the past.

Edit: Crap..no idea what engine you have. I have the 4.7...
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Unread 04-28-2013, 12:29 PM   #3
Ravie
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4.0
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1999 WJ - Over 10k on the 4.0 rebuild. FB/BDS 2" lift (2.5") w/Bilstein 5125's. General Class Ham...KC0LUA
Burlbook48 sez "Nothing moves a project along faster than cubic dollars." Certified Thread Killer.
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Unread 04-28-2013, 07:33 PM   #4
sixmikey9
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2003 WJ 
 
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My 03 had the same problem, I had the p0505 code. The culprit was the wiring harness connector. I had to bend the contacts to make a better connection. Hope this helps!
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Unread 04-28-2013, 07:39 PM   #5
Ravie
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which harness?
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1999 WJ - Over 10k on the 4.0 rebuild. FB/BDS 2" lift (2.5") w/Bilstein 5125's. General Class Ham...KC0LUA
Burlbook48 sez "Nothing moves a project along faster than cubic dollars." Certified Thread Killer.
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Unread 04-28-2013, 09:07 PM   #6
sixmikey9
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The connector that plugs into the iac valve. Also check the wiring all the way back to the computer. These are notorious for having problems, especially where the wire loom goes around the back of the valve cover. You might see where the stud sticking up on the rear driver side has worn into the wires thus shorting them to ground and causing your idle issues.

Also, when mine started doing it, there were no codes at first.
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Unread 05-01-2013, 08:35 PM   #7
Ravie
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made sure the pins were tight, checked for air leaks, installed a new IAC (the plunger was in a noticeably different position than the one I pulled out so I figured this would do it...)...

Nope. It goes through the "relearn" procedure and once again the lowest it idles is 1300 in park or neutral. I put it in gear and it drops down to about 750rpm, just like it should..

I'm at a loss. No codes, drives fine.

Is it possible that the computer needs to be reflashed after having had that Jet chip on there for so long?
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1999 WJ - Over 10k on the 4.0 rebuild. FB/BDS 2" lift (2.5") w/Bilstein 5125's. General Class Ham...KC0LUA
Burlbook48 sez "Nothing moves a project along faster than cubic dollars." Certified Thread Killer.
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Unread 05-01-2013, 08:38 PM   #8
Ravie
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Location: Topeka, KS
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Another stroke of genius:

So, when it was messing up real bad it was dumping gas like crazy into the tailpipe, running so rich it was actually shooting black gasoline out of the back. Is it possible that my O2 sensors are all gunked up now?
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1999 WJ - Over 10k on the 4.0 rebuild. FB/BDS 2" lift (2.5") w/Bilstein 5125's. General Class Ham...KC0LUA
Burlbook48 sez "Nothing moves a project along faster than cubic dollars." Certified Thread Killer.
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Unread 05-02-2013, 06:49 AM   #9
adolphhipster
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On the high idle problem. I had this and it threw a bad alternator code. Changed it with a 160 durango alt and now its idle perfect.
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Unread 05-07-2013, 03:05 PM   #10
sixmikey9
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You ever do a computer reset, aka, disconnect battery cables, give it a while and then reconnect? Otherwise wjhahn might be on the right path. Might want to do a vacuum test. Don't have the specs in front of me, but 15 inches of mercury might be the target for a vacuum gauge. I don't know for sure about your o2 sensors, but they are probably fine. You are seeing water vapor that has condensed. Double check your hoses etc on top of valve cover. Good luck.
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Unread 05-07-2013, 03:09 PM   #11
kentman
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For my WJ, it was the TPS.
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