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Unread 06-01-2013, 07:26 PM   #1
ctappan94
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2012 JK 3.6 Cylinder 2 Misfire

Hey all,

Tell me what to do here. I have had a ticking on the left side of my 3.6 pentastar for the last few thousand miles. I've noticed decreased MPG & significant power loss. I took it to the dealer a month or two ago & told the tech it might be a bad head. The tech said I was wrong & that it was "normal," but that if it persisted, I should bring it in again...(however idiotic that may sound). Recently, the CEL came on & I hooked an OBD scanner up to it, and it indicated 3 permanent accounts of "Cylinder 2 misfire." More research into it showed that this is the typical symptom of a bad head. Do I call up and yell at them about telling me I'm wrong without even checking anything? Or should I try another dealer..??

Thanks guys

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Unread 06-01-2013, 09:51 PM   #2
shaynes
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I had the same issue and my dealer replaced it with no questions asked. I had another friend that had his fixed, too. Runs like a charm now!
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Unread 06-01-2013, 11:39 PM   #3
ctappan94
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and furthermore, is it rational for the dealer to replace both heads? It's illogical to have one defective head that's acquired 15,000 miles on it be replaced with a head with zero miles on it... one with 15K & another with 0 is far less than perfect...
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Unread 06-02-2013, 10:58 AM   #4
Godholio
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There should be basically no wear on a 15k mile head. Unless there are other problems contributing, heads aren't really wear parts. My other car is still running the original heads after 47 years, and the engine has never been cracked open.
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Unread 06-02-2013, 11:37 AM   #5
222Doc
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Quote:
Originally Posted by ctappan94 View Post
and furthermore, is it rational for the dealer to replace both heads? It's illogical to have one defective head that's acquired 15,000 miles on it be replaced with a head with zero miles on it... one with 15K & another with 0 is far less than perfect...
its not a matter of wear. It is a matter of defective parts( perhaps design) and in this case the heads on both sides. The next code If the new head is really fixed will be miss fire on 6#. The head they left on. Knowing that it may get by the warranty.
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Unread 06-02-2013, 11:22 PM   #6
djm
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I am far from an expert, and I am sure others will chime in and share their knowledge, but I think that it has always been the same issue, the head on the same side, cyl #2 that had the problem. Because of that it actually sounds like there was a manufacturing defect on the one head, it's apparently been corrected as no one that I know of, has had to go back with the same problem once the one head was replaced.

I have the issue on my 2012 JKU Sport, CEL came on, brought it in, because of the known problem and how many of those engines are out there, my dealer stocks the head, took him 3 days and had it done.

Dan - NJ
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Unread 06-03-2013, 12:06 PM   #7
ctappan94
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ah ok so replacing just one is okay??
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Unread 06-03-2013, 12:40 PM   #8
Spank
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I'm getting the CEL with P0306 as well, but it'll stay on for a day or two, then disappear for a couple days, then come back. The engine isn't suffering from any performance issues, nor is there any tapping sounds from the engine indicative of a bad head.

Dealership A declined to look at my Jeep because I wheeled it.

Dealership B simply cleared the code and sent me on my way. It came back a few days later.

Dealership C is telling me the PCM needs to be reflashed, which is what I told Dealership B to do in the first place, so hopefully this'll be the end of it. Right now I'm having to fight with them getting it covered under warranty. I'm not going to pay $130 to have some guy spend a couple minutes flashing a computer that I didn't break, nor is a maintenance (or even lack there-of) problem.
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Unread 06-03-2013, 02:38 PM   #9
Godholio
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Quote:
Originally Posted by ctappan94 View Post
ah ok so replacing just one is okay??
Yup. They're not identical or matched in any way. Each side is a unique design.
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Unread 06-03-2013, 03:22 PM   #10
Orange1
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Same problem here - ugh!

I have just discovered two misfires at #2 cylinder in my 2012 Automatic JKU with 7800 (road) miles. What a kick in the butt - I am wondering if they will warranty as I have extensive upgrades to the drive train??????
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Unread 06-03-2013, 04:06 PM   #11
brianjw
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Quote:
Originally Posted by Orange1
I have just discovered two misfires at #2 cylinder in my 2012 Automatic KJU with 7800 (road) miles. What a kick in the butt - I am wondering if they will warranty as I have extensive upgardes to the drive train??????
There is no reason they shouldn't. Downstream drivetrain changes don't cause a well known faulty head problem.

Not to say that some dealership service departments aren't jerks but they should cover it.
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Unread 06-04-2013, 08:51 AM   #12
ctappan94
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I've had some idiot techs, too...... In my 2011 GTI (before the Jeep), I told them my engine would stay running for all of 30 seconds then die.... They blamed it on my new fog light bulbs....... in actuality, the entire ECM and on board computer needed replacement...
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Unread 06-06-2013, 01:04 PM   #13
ctappan94
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Well its in the shop today..let's see what happens!
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