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Head replacement for a misfire (code 304)?

Discussion in 'Wrangler JK (2007-2017)' started by skiteach, Dec 3, 2017.

  1. Dec 3, 2017 at 3:28 PM
    #1
    skiteach

    skiteach [OP] Member

    Joined:
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    2012 JK Un
    Our 2012 JK has 100,500 miles when check engine light came on. Code 304, replaced spark plugs, all, and coil on number 4. Code comes back. It's now at the dealer. Head replacement. My question is; Why are these heads being replaced for a misfire situation? Dealer hasn't answered the why. I was a ASE Cert Master, left the trade as I was becoming very allergic to all the chemicals that we used, maybe causing my bout with Leukemia. So I looking for a reason for replacement. 80's Audis were breaking exhaust manifold bolts and they were covering head replacement for that. It was very difficult to extract the broken studs.
     
  2. Dec 3, 2017 at 5:46 PM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Welcome! Some of the earlier heads had issues with leaking, or cracking. A TSB was issued, and heads were being replaced under warranty. Not sure how long the warranty replacement was for. Might not hurt to ask the dealer.
     
  3. Dec 3, 2017 at 6:43 PM
    #3
    aggrex

    aggrex Well-Known Member

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    DE
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    Backcountry '16
    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    Just like @chris4x4 mentioned about past TSBs. As you know some TSBs are not common knowledge. I was fortunate last month a TSB existed for my 2011 Outback AT. The TSB centered on torque converter failure once the car approaches 100k. No recall, no notices until years later as more people complain. Outback is fixed but I'm spreading the word on that TSB.
     
  4. Dec 3, 2017 at 6:55 PM
    #4
    JKBob 25

    JKBob 25 Well-Known Member

    Joined:
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    Jersey Shore, NJ
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    Welcome to the forum skiteach.
    Awesome info posted above that I was not aware of. So i picked up some knowledge also. Thanks guys.
     
  5. Dec 4, 2017 at 6:52 AM
    #5
    skiteach

    skiteach [OP] Member

    Joined:
    Nov 28, 2017
    Member:
    #2011
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    12
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    Male
    Vehicle:
    2012 JK Un
    We purchased the JK used, also an extended warranty. Radiator and heater core were replaced, due to lack of heat. We received a Warranty Extension, for the left cylinder head, from FCG, or what ever they are calling themselves this month. So one head is covered. Still waiting to see what entire process is! Even the internet has very little info on this! I worked at a Dodge Dealer, for a short time in 1988. Chrysler had a few problems with valve guides around the time I left the trade. Now I bang nails and butcher long lengths of wood. Finish Carpentry is easier on the body!
     
    Billy1234, JKBob 25 and chris4x4 like this.

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