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Unread 09-22-2014, 12:27 PM   #1
scarbogarage
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JK 3.8 Slow to return to idle

I have a nagging issue that I wanted to put out there before i dig too deep. My '08 JK with a 3.8 6-sp is slow to return to idle while shifting and/or coming to a stop. The idle will hang at about 2000 rpm for a second or two then slowly return to idle. I can't reproduce it by just revving the motor up and i only see it when shifting, slowing down or coming to a stop after driving. Once it returns to idle it stays that way unless I resume driving.
Any ideas?

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Unread 09-22-2014, 12:37 PM   #2
ncb
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Mine is the same way. It doesn't effect the shifting or shifting smoothly though. It's probably in the computer tuning to keep revs up for shifting. I remember rebuilding the carb on my old Toyota pickup back in the day and it had an adjustment to keep the revs up between shifts.
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Unread 09-22-2014, 12:47 PM   #3
scarbogarage
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NCB i have figured it is the computer keeping the revs up but i drives me crazy. Anybody know if there is a fix or if any of the programmers override this?
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Unread 09-22-2014, 12:53 PM   #4
ncb
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There's the Sprint Booster and other programmers that can change throttle sensitivity, but I'm not sure if it removes the hang it has while RPM decreases. Hopefully someone with a programmer will chime in.
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Unread 09-22-2014, 04:49 PM   #5
RockyClymer
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When they gave me the custom tune for my RIPP, it removed the slow idle return...expensive way to solve it lol
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Unread 09-22-2014, 04:54 PM   #6
scarbogarage
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That is good to know that it can be solved by a "tune" so there is hope!!!
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Unread 09-23-2014, 09:13 AM   #7
JIMBOX
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Ronjenz can probably point out the source check and I would think that the Throttle Position Indicator (TPI) is either oiled/dusted/defect !

Good luck

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Unread 09-24-2014, 06:24 AM   #8
ronjenx
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Quote:
Originally Posted by scarbogarage View Post
I have a nagging issue that I wanted to put out there before i dig too deep. My '08 JK with a 3.8 6-sp is slow to return to idle while shifting and/or coming to a stop. The idle will hang at about 2000 rpm for a second or two then slowly return to idle. I can't reproduce it by just revving the motor up and i only see it when shifting, slowing down or coming to a stop after driving. Once it returns to idle it stays that way unless I resume driving.
Any ideas?
Have someone video the tach and speedometer while you're running through the gears so we can see exactly what it's doing.
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