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Unread 04-09-2012, 04:03 PM   #1
01jeepGCL
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Join Date: Jun 2007
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Wj Weird engine problem (Kind feels like misfire)

I have been having a problem with my jeep (2001 4.0L automatic) for some time now and only seems to show it's ugly face when the weather is above 80*.

I start the Jeep, everything runs fine. I drive for a time frame of longer than 15 minutes (the jeep gets warmed up) and the temp gauge is right below the middle as it should. Say I stop and grab some food (5-10min stop). I get back in the Jeep and and crank her up. She starts up with no problem but the motor starts shaking and gets worse if I rev the engine a bit. I don't get an check engine lights or anything. I did notice that when this happens my temp gauge goes a little above the middle of the gauge. Then it starts to move back to a normal temp. condition. The shaking stops when the temp needle drops. I have never overheated before but this is the only time it happens. Could this just be a bad sensor? I'm not familiar with the wiring but on my Acura Integra the gauges was controlled by a single wire to a sensor and did not run to the computer at all. Does this gauge read from the ECT sensor? If anyone could help I would appreciate it.

Thanks,
Ryan

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Unread 04-12-2012, 09:56 PM   #2
ddtwdmb
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Have you run the diagnostic procedure? See if it's getting any error codes, easy to do, read about it at http://www.wjjeeps.com/faultcodes.htm ..if it's a sensor it may show up, even without the check engine light coming on.
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Unread 04-12-2012, 10:11 PM   #3
pinky2252s
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Same thing happened to me on my V8. I replaced the TPS (Throttle Position Sensor) and it solved it.
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Unread 04-12-2012, 10:29 PM   #4
ddtwdmb
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Quote:
Originally Posted by pinky2252s View Post
Same thing happened to me on my V8. I replaced the TPS (Throttle Position Sensor) and it solved it.
Same here
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Unread 04-12-2012, 10:44 PM   #5
BWYoung85
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2004 WJ 
 
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Heat Soak causing a misfire on injector 3, TSB Link: http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf

I had this exact problem with my WJ when it started getting warmer outside. I used Reynolds Heavy Duty aluminum foil, and folder over until it was about 1/16 of an inch thick and wrapped injector 3 and 4 and secured it with zip ties. 3 and 4 are at the center of the motor and are exposed to the most heat once the engine is turned off. I also wrapped my fuel rail around this area as well. I know it sounds farfetched, but it worked for me. Before you go replacing sensors try this out. Let us know how it works for you.
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Unread 06-29-2012, 09:24 AM   #6
01jeepGCL
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Quote:
Originally Posted by BWYoung85 View Post
Heat Soak causing a misfire on injector 3, TSB Link: http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf

I had this exact problem with my WJ when it started getting warmer outside. I used Reynolds Heavy Duty aluminum foil, and folder over until it was about 1/16 of an inch thick and wrapped injector 3 and 4 and secured it with zip ties. 3 and 4 are at the center of the motor and are exposed to the most heat once the engine is turned off. I also wrapped my fuel rail around this area as well. I know it sounds farfetched, but it worked for me. Before you go replacing sensors try this out. Let us know how it works for you.
I will give this a shot. It only happens on hot days 90* +. And more so when I run my a/c it seems. I will check to see if I have any codes on my lunch break. I was going to try to just turn the power on and see where the temp needles goes. Like I said it only happens when the needle goes passed halfway on the temp gauge. If I let the jeep run a minute the needle moves back to half way and the idle stablizes. Kinda of strange. I will give the foil a try and check the codes.

I will let you guys know how it goes. The heat index is in the 100's already so I should be able to get see the symtoms. I'll try to get a video as well.
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Unread 07-01-2012, 10:27 AM   #7
n61870
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If none of those things work, here's another $.02...My Jeep was doing something similar, I thought it was a heat problem but then it started doing it in the cold, I thought it was a throttle position sensor but both myself and a mech checked it and it was good. Anyway, I finally ran across a tech bulletin about the 4.0L exhaust valves sticking, causing the engine to run rough. The solution was to use the Mopar cumbustion chamber cleaner. I used the cleaner and followed the instructions, havent had the problem since. Do a search for that particular service bulletin because the instructions in the bulletin and the instructions on the can are different. I think the cleaner was around $10 at the dealer, I bought 2 just in case but one was enough so I ran the other through my old ford ranger and it actually improved the gas mileage.
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Unread 07-01-2012, 11:10 AM   #8
ZB_WJ
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What grade gas are you using? Ethanol free?
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Unread 07-02-2012, 10:01 AM   #9
01jeepGCL
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Im using 87 octane and I'm sure it's got some amount of Ethanol mixed in with the fuel. I didn't think the jeep needed higher octane fuel. I only run the higher octance (93) on high compression or forced induction.

I will look into the Mopar cleaner. I'm sure it wouldn't hurt. Either that or Sea Foam.
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Unread 07-02-2012, 10:12 AM   #10
coloboardin
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I'm glad this was posted, I'm having the exact same issues right now. It was 102* yesterday and had a very rough start. If the CEL isn't on will it still throw a code?
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Unread 07-02-2012, 10:15 AM   #11
ZB_WJ
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I've got 04 4.0 auto and mine did same last summer. Almost exactly. Would drive, stop at food place and then start it up. Would run rough and shake. I was so mad, id just bought it. I read about heat soak and it sounded like my problem. When I was using cheap gas is when it happened. I would just stomp on the gas a few times to clear out injectors, would be fine till I hit a stoplight. Then it would run rough again. I changed my gas station and only use ethanol free premium, hasn't done it once this year luckily with 106 temps. I haven't done anything else besides better gas. Just my experience.
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