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Old 07-12-2013, 09:31 PM   #1
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Hey there im new to the board but have creeped it for about 2 years now. I have a 2000 tj 4.0 5 speed. When the engine is cold it runs pretty much on 5 cylinders till it warms up then it misses once every few seconds at idle. When its warm it drives fine until you start to accelerate hardish or climb a hill. Then it starts to stumble and then it knocks/clunks that you can feel in the gas pedal. This can be at any rpm. I have replaced the spark plugs with champion 7034s (distributerless ignition). The spark plug on cyl 1 is covered in soot. Check engine light P0301. The engine is completely stock. The jeep has a 2" lift and 32s on stock axles with 3.07 gearing. Im just used to magetos and carbs on planes so im a bit lost when it comes to computer stuff haha. Any advise is greatly accepted!

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David

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Old 07-12-2013, 09:59 PM   #2
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Bad fuel injector?

Each of the 3 coils fires 2 cyls, so if only one cyl is misfiring, that rules out the coil pack.

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Old 07-12-2013, 10:16 PM   #3
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Bad fuel injector?

Each of the 3 coils fires 2 cyls, so if only one cyl is misfiring, that rules out the coil pack.
How do I test injectors? Its only ever been the P0301 code. And only the cyl 1 sparkplug is sooty
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Old 07-12-2013, 10:38 PM   #4
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You can use an ohm meter to check the resistance of it and compare it to the others.

You can also move the injector to another cyl and see if the misfire follows.
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Old 07-13-2013, 04:27 AM   #5
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When its warm it drives fine until you start to accelerate hardish or climb a hill. Then it starts to stumble and then it knocks/clunks that you can feel in the gas pedal. The jeep has a 2" lift and 32s on stock axles with 3.07 gearing.

Thanks!
David
This may just be because of the size tires you have with 3.07 gearing. 32s are a little much for that if I'm not mistaken. Basically makes the jeep a 4 speed and would be most noticeable under heavy load/uphill.

The knock you describe almost sounds like a bad catalytic converter. Does it sounds like it's choking when you get deep into the pedal?

Another consideration might be a bad O2 sensor.
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Old 10-05-2014, 12:06 PM   #6
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I have the same problem on my 2004 TJ 4.0.

I know it is not the injectors as I swapped cyl 1 and cly 2 injectors, and the problem stayed on cyl 1.

I replaced all the plugs, and still have the same issue.

I did a compression test, and all appears to be fine there.

I am trying to figure out where the crankshaft sensor is, to test that, but others have said in other threads that if it was the crank sensor, it would be random cyl misfires.

And other threads also stated that if the problem was with the coil, then then i would also be getting a misfire on cyl 4, since the coils fires two cyl at once.

I am wondering what your solution to this was

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