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Error Code P0300, P0303, P0304

Discussion in 'Wrangler TJ (1996-2006)' started by bwilson9, Sep 24, 2019.

  1. Sep 24, 2019 at 3:04 PM
    #1
    bwilson9

    #1
    bwilson9 [OP] Member

    Joined:
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    Brian
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    2002 Jeep Wrangler TJ
    Oversize Tires, Lift, Bumpers
    I have a 2002 Jeep TJ Wrangler and I keep getting the error codes P0300, P0303, and P0304. These errors refer to a "firing" issue. I have replaced all the plugs, no fix. I replaced the coil pack, no fix. I'm not sure what else it could be. Has anyone else worked with this problem?
     
    bwilson9, Sep 24, 2019
    #1
  2. Sep 24, 2019 at 7:31 PM
    #2
    JKBob 25

    #2
    JKBob 25 Well-Known Member

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    Jersey Shore, NJ
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    Plugs and coil pack replaced. Misfires in 3 different cylinders.
    Im not very fimilar with your TJ. But just off the top of my head.
    Wires? Distributor? Any recent ignition work Recently? Any other info can help.
     
    JKBob 25, Sep 24, 2019
    #2
  3. Sep 25, 2019 at 6:51 AM
    #3
    Awrench

    #3
    Awrench Well-Known Member

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    Yeah those P030x codes are confusing, you see misFIRE and think SPARK or secondary ignition BUT the FUEL system and MECHANICAL can cause the misfire.
    You replaced the coil RAIL and replaced the plugs. A common place to start...hopefully you kept the old coil,
    what plugs did you use? it matters RC12ECC is correct plug let us know. Next I would add a can of 'seafoam'
    fuel treatment. And have a scan done at the auto store, copy and post ALL codes along with info asked for.

    Anything you can add - modifications (powertrain), recent repairs, deep water, bullet holes, accidents ?

    NOW if the code continues a scanner is the ideal tool, to start check for all codes, look at live data ECT,MAP, TPS, fuel trims and o2 sensor voltages.
     
    Awrench, Sep 25, 2019
    #3
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