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Discussion Starter · #1 ·
We just acquired a 2007 wrangler, I have replaced the coil pack, plugs and wires and still have a pretty good miss. Getting random misfire codes. What would be the next thing to check or replace in this frustrating process of elimination. Any help is much appreciated. 3.8 L
 

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Sounds like the only thing you haven't changed was the camshaft positioning sensor, If I'm not mistaken that will cause your symptoms.
 

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Don't misunderstand, I'm not saying that is what it is, This is just a stab in the dark just as any parts swap diagnosis is.
I assume you do not have a full fledged diagnostic tool that you would be able to monitor the sign wave/pulse of the CPS to confirm there is a skip in its function, so until we are all equipped with this sort of diagnostic equipment it's either parts swap diagnosis or bring it to a shop and pay for their equipment.
For the most part it's what I am left with also when things don't function as they should, Good Luck.
 

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Discussion Starter · #5 ·
Moab , I am just thankful that u took the time to reply!! To my first post... U gave me direction thanks
 

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I bet if you look under the hood you'll find the engine. :p

Seriously though, it could be any of a number of things.

I had a bad batch of gas cause multiple random misfires. It had some water in it. And water doesn't burn as well as gas.

It could be spark plugs or wires. It could be a bad connection at the coil. It could be a bad coil.
 

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Derf thanks for ur knowledge !!! Engine local was most helpful.!
Happy to be of service. :)

My trouble with the bad gas showed up the day after I filled up. The water settled overnight and caused the "multiple random misfires" code to show up the next day as soon as I got on the freeway a few blocks from the house.

Just one more thing to look into.
 

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We just acquired a 2007 wrangler, I have replaced the coil pack, plugs and wires and still have a pretty good miss. Getting random misfire codes. What would be the next thing to check or replace in this frustrating process of elimination. Any help is much appreciated. 3.8 L
Can you provide the codes?
Without the them, any 'help' would really just be a guessing game with you footing the bill (in parts).
 

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Did you check the couch cushions? Whenever my remote is missing it is in the cushions.
 

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The two codes that r showing up are
P0304....#4 misfire
P0171.....bank 1 lean
Sounds like a fuel delivery issue. Could be clogged injectors or crap in your fuel line. I'd start with a fresh fuel filter and run a tank of fuel system cleaner through the Jeep. That might fix it and doesn't cost much at all.

If not, you may need to replace injectors or the fuel pump.
 

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Discussion Starter · #14 ·
Thanks for the advice Derf I will certainly start with the lest expensive But what sucks is my fuel filter (from what I understand) is in my gas tank.
 

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Correcting the 'misfire code' comes first. The 'lean condition code' could be a result of the misfire.
Without further testing (ie-by codes only), I would lean towards replacing cylinder #4 fuel injector (depending on mileage, maybe all injectors).
 

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Does it miss at idle. Or does it have to be under load. If it misses all the time idle or under load you may want to check compression on that cylinder. You can always swap injectors to eliminate that as well
 

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Lean and Misfire would point me to fuel as well. If it were misfiring on the ignition end, it damn sure would not be lean on that bank as it would be dumping raw/unburnt fuel from that cylinder that didn't burn at ignition.

That's my $.02. Other things could be a compression issue ($$$) or a bad CPS as mentioned as well, but I think it would be a constant issue if either of those were going on.
 

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Overly lean conditions can also lead to misfires if you get them lean enough.

A clogged injector could be all that's wrong and a bit of cleaner may be all it takes.

It's likely to be more but trying out the cheap and easy thing first is best when its on your dime. You never know. It may just solve the problem. And if not, you've still run cleaner through the fuel system and on an 8 year old vehicle, that's not a bad thing to do anyway.
 

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Discussion Starter · #19 ·
It seems to only miss under a load, thanks for all the input! Will keep posted and pray I can get this probl resolved soon
 

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Discussion Starter · #20 ·
Here is what I am facing now, I replaced the injector put everything back together and the engine started right up... But tons of smoke out of the exhaust and because of a exhaust leak I noticed raw fuel seepage. Did I not do something I should have, I am so frustrated and have no clue what to do now
 
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