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  #1  
Old 07-29-2015, 07:30 PM
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Intermittent rough idle

So...VERY RARELY...I'll come to a rather abrupt stop at a stoplight or something and the engine RPMs drop a little below where I like them to. It doesn't stall, but it almost feels like it's going to. It quickly recovers and idles normally while sitting at the light. I then take off in normal fashion and everything is fine. This doesn't happen often at all, but I have noticed it a handful of times over the last few months. I don't think it's ever happened during a slow stop. Only during a more abrupt one.

I have no engine lights, no codes, no nothing. It doesn't throw any lights or codes when it happens either. TB is squeaky clean, and I've got new cam and crank position sensors (mopar). It's up-to-date on all of its maintenance. Any ideas?

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  #2  
Old 07-30-2015, 03:29 AM
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Re: Intermittent rough idle

Quote:
Originally Posted by TJXJWJ View Post
So...VERY RARELY...I'll come to a rather abrupt stop at a stoplight or something and the engine RPMs drop a little below where I like them to. It doesn't stall, but it almost feels like it's going to. It quickly recovers and idles normally while sitting at the light. I then take off in normal fashion and everything is fine. This doesn't happen often at all, but I have noticed it a handful of times over the last few months. I don't think it's ever happened during a slow stop. Only during a more abrupt one.

I have no engine lights, no codes, no nothing. It doesn't throw any lights or codes when it happens either. TB is squeaky clean, and I've got new cam and crank position sensors (mopar). It's up-to-date on all of its maintenance. Any ideas?
Any other symptoms? I was having similar symptoms, but they have progressed to high idle on cold start. Fairly certain it is IAC in my case...waiting on part. It might also be TPS?

Hard to trouble shoot when it is intermittent like that. Easier once it got worse though. You could also check for vacuum leak, but I'd bet it is unlikely since you have no other symptoms.

HTH,
Phil
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Old 07-30-2015, 06:46 AM
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Re: Intermittent rough idle

Quote:
Originally Posted by p3vinny View Post
Any other symptoms? I was having similar symptoms, but they have progressed to high idle on cold start. Fairly certain it is IAC in my case...waiting on part. It might also be TPS?

Hard to trouble shoot when it is intermittent like that. Easier once it got worse though. You could also check for vacuum leak, but I'd bet it is unlikely since you have no other symptoms.

HTH,
Phil
When the IAC doesn´t throw a code (and the IAC stepper motor plunjer and air channal are clean), then most probably idle problems are caused by the TPS. Eventually a not well releasing torque converter clutch can cause stalling.
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Old 07-30-2015, 06:49 AM
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Re: Intermittent rough idle

Quote:
Originally Posted by Frango100 View Post
When the IAC doesn´t throw a code (and the IAC stepper motor plunjer and air channal are clean), then most probably idle problems are caused by the TPS. Eventually a not well releasing torque converter clutch can cause stalling.
Are there any other symptoms of a sticky torque converter clutch?
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Old 07-30-2015, 08:24 AM
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Re: Intermittent rough idle

Not that i know of.
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Old 09-19-2015, 01:53 PM
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Re: Intermittent rough idle

Im having the same prob. Its worse on HOT days. Im thinking Idle/Air sensor. You can take it out and lightly sand and clean or $60 new with a 10-min install time. Thats next om my list after rear brake pads.
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Old 09-20-2015, 04:26 PM
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Re: Intermittent rough idle

Sitting at 130k miles and I end up with the same thing every now and then. I cannot find any pattern (weather, temps, humidity, ???) that leads to the behavior either. I probably need to clean the IAT again since I did that at 80k miles when it got the WJ.

Part of me wonders if the problem is the one behind the wheel...
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Old 09-20-2015, 05:04 PM
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Re: Intermittent rough idle

O2 sensor will do that as well... went thru this on one of my Durangos..

But first clean up the IAC passages, and maybe swap the TPS.. both cheap and easy..
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Old 09-20-2015, 06:26 PM
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Re: Intermittent rough idle

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Originally Posted by tomk View Post
O2 sensor will do that as well... went thru this on one of my Durangos..

But first clean up the IAC passages, and maybe swap the TPS.. both cheap and easy..
New o2 sensors and plugs at 80k miles too.
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Old 09-25-2015, 08:45 PM
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Re: Intermittent rough idle

I replaced all of my O2 sensors about 2 years ago with OE ones. I picked these up today...installation tomorrow. Hopefully that clears it up. It's rare that it happens, but it's worth a shot. Both of these are original from 2004 and are probably on their way out anyway.
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