WJ rough idle, NEED HELP ASAP!!!!!!!! - JeepForum.com

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post #1 of 8 Old 11-03-2009, 07:39 PM Thread Starter
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WJ rough idle, NEED HELP ASAP!!!!!!!!

Jeep had a bout 2 1/2 gal in the tank and started idleing a little rough. Affter getting gas the jeep continued to idle rough and when the engine downshifted during accerleration it acted as though it wanted to stall. Let the jeep for multiple hours while at work and problem continued on way home. Check enigne light was already on for an emissions leak, however; once speeds in excess of 25 miles an hour were reached the check engine light began to flash intermintely. As speeds were decreased and engine returned to idle flashing stopped. Repeated problems entire ride home.

Once at the house, I put in park and reved engine the engine sputtered at around 2700 rpm. Restarted engine rough is still apparent though sputtering is no longer an issue while in park. No noise is apparent for engine bay, though a slight exhaust leak may be heard while standing beside vehicle.

Have not had an opportunity to attach OBDII to aquire engine codes as of yet.

Coworkers suggested fuel pump or filter, but I have run the tank dry before and never had a problem. All input would be welcomed.

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post #2 of 8 Old 11-03-2009, 07:41 PM Thread Starter
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Also fuel pump and strainer were replaced a few months back while trouble shooting a problem that turned out to be a crank sensor.
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post #3 of 8 Old 11-04-2009, 08:36 PM Thread Starter
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Engine ran fine this morning until It warmed up and I hit stop and go traffic. Now the problem is back.
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post #4 of 8 Old 11-04-2009, 08:43 PM
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have you checked the TPS = throttle position sensor or MAP sensor ?

Both of those would cause rough idle.


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post #5 of 8 Old 11-04-2009, 08:52 PM
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def. pull that code and see what that problem is.

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post #6 of 8 Old 11-04-2009, 08:59 PM Thread Starter
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just pulled the codes and they read out as follows:

1. P0122- TPS/ Pedal Position sensor A circuit low input

2. P0135- O2 sensor heater circuit malfunction (bank 1 sensor 1)

3. P0303- Cylinder 3 misfire detected

4. P0455- EVAP emission control leak (large)

5. P0442- EVAP emission control leak (small)

6. P0456- EVAP emission control system leak very small.

I would appreciate suggestions of where to start seeing as how I go on deployment in less than 2 weeks and have very little time to get the jeep running right before having to place in storage for months.
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post #7 of 8 Old 11-04-2009, 09:30 PM
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TPS and O2 can cause the rough idle and themselves may have tripped the #3 misfire...

Pull the O2's and see if they are plugged and you can test the TPS with a voltmeter.

Good luck


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post #8 of 8 Old 11-04-2009, 09:51 PM
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Oh and BTW you probably want to get this fixed soon as a flashing CEL means there is something major that is wrong. I would start with the O2 sensors and the TPS and go from there as those two things can cause problems you have.
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