Rough idle that will not go away - JeepForum.com
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post #1 of 19 Old 05-04-2013, 08:18 AM Thread Starter
jboylan
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Rough idle that will not go away

Hi all this is my first post to this forum. I recently purchased a 06 3.7 with 118k miles on the clock currently and I love it except for the rough idle it has developed.
I have no codes showing
I have followed all the tips in other threads and so far:
I have installed a new tps
Changed spark plugs (got them at the dealership gapped to .042)
New PVC valve
Cleaned throttle body
Ran injector cleaner through tank
Cleaned iac motor
Checked trans fluid level

It still dips below 500 rpm at lights and bounces back up and has a shake at idle
What should I look at next?

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post #2 of 19 Old 05-04-2013, 08:52 AM
paroxysym
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have you done seafoam through the brake booster?

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post #3 of 19 Old 05-04-2013, 09:01 AM Thread Starter
jboylan
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Not yet. I'm having trouble finding the thread with the write up for that. Do you know the procedure?
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post #4 of 19 Old 05-04-2013, 09:36 AM
paroxysym
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locate the brake booster- theres a vac line connected to it, disconnect it and pour the bottle of seafoam in the line, slowly- almost making it stall out. let it sit for 20mins after dumping the whole can in the jeep. go out start it up and take it for a spin, and really keep the RPMs up to burn all that seafoam/carbon build up out of the motor. should help

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post #5 of 19 Old 05-04-2013, 10:30 AM
enkeivette
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I would have guessed the idle slot/ port in the throttle body, if the problem is only at idle, you sure you cleaned it well enough? Change the fuel filter, pull out the injectors and hit the tips with carb cleaner, finally check the sock in the gas tank for a clog.
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post #6 of 19 Old 05-04-2013, 10:40 AM Thread Starter
jboylan
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I thought the fuel filter for the 3.7 was on the fuel pump in the tank? Is there one on the frame or in the engine bay?
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post #7 of 19 Old 05-04-2013, 11:10 AM Thread Starter
jboylan
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Tried the sea foam and no change. Still surging and rough idle.
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post #8 of 19 Old 05-04-2013, 12:33 PM
ca07wk
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Fuel filter is in tank.

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post #9 of 19 Old 05-04-2013, 04:10 PM
mg2125
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Sounds dumb (and if you've installed a cold air induction kit then it's a moot point) but I traced a similar problem on my WK to an incorrectly latched air box lid. See I had replaced the air filter during an oil change and did not install the top of the air box correctly; as soon as I reattached the lid correctly, the idle problem went away.
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post #10 of 19 Old 05-04-2013, 05:14 PM Thread Starter
jboylan
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I just checked. Lid is secure. Thanks for the tip tho
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post #11 of 19 Old 05-14-2013, 05:54 PM Thread Starter
jboylan
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Update: took the jeep in for p0023 and p0506 code that got thrown on my trip last weekend. They also found u0401 and said that the sensor parameters were way off and I was getting bad signals from the new sensors. My mechanic reset everything yesterday and it ran fine this morning. I had all the same codes come back this afternoon and went away and came back and went and so on. The only one still there is u0401. Invalid data from ECM pcm. Is it time to order a new computer(ECM/pcm)???
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post #12 of 19 Old 05-16-2013, 09:41 AM
chevra
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I had a bad o2 sensor cause similar problems once before.

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post #13 of 19 Old 05-16-2013, 09:57 AM Thread Starter
jboylan
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Just changed o2 2 hours ago. Stuck in traffic right now on I-81 and the idle keeps dropping out and getting rough. Hasn't stalled yet but it feels like it wants to. Also noticing some rough shifts when I'm on and off the gas in traffic
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post #14 of 19 Old 05-16-2013, 02:22 PM
sunnysal
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I have the 4.7 v8 and have the same problem. I replaced; MAP, TPS, IAC, PCV Valve, Spark plugs and the air filter. still have VERY lumpy idle, has never stalled though. I get about 10.5 miles to the gallon, which seems low to me. the advice here led me to change all those items but still it has a crappy idle. I will be watching your thread to see if and how it gets solved. regards, T
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post #15 of 19 Old 05-17-2013, 04:41 PM Thread Starter
jboylan
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It must be something in the transmission. I had to have it towed off the highway today. It lost power and started slipping. I'll keep you posted next week as to what they find wrong. They said probably the pump or the valve body but I will post as I know more
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