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HELP!! P304 Code/Cant Pass emissions

Discussion in 'Technical Chat' started by damionseacat, Mar 4, 2012.

  1. Mar 4, 2012 at 9:08 AM
    #1
    damionseacat

    damionseacat [OP] Member

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    So, after replacing spark plug wires and cables and clearing the check engine light. The light came back on and I'm getting the P304 code again. My question is whether the check engine light can turn off after a week of driving with the new plugs and cables?

    Thanks for any help! :)
     
  2. Mar 4, 2012 at 9:44 AM
    #2
    Yamaha Dave

    Yamaha Dave Well-Known Member

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    Sometimes they do, but when my O2 sensors went out, I just took the terminals off the battery for 15 mins. to reset to ECU. No more Check Engine light, and took it immediately to get my inspection sticker. But it always will come back on unless you correct the problem.
     
  3. Mar 4, 2012 at 3:48 PM
    #3
    jinxed77

    jinxed77 Well-Known Member

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    If they check the ready status monitors by doing a computer scan you can't do that.
     
  4. Mar 4, 2012 at 4:08 PM
    #4
    Rich91710

    Rich91710 Well-Known Member

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    Ditto.
    Won't work in California unless all of the monitors have passed clear.
    Not too often you can just reset and pass... maybe some hick towns where the inspector is just looking for a light, in which case a piece of tape would make it pass :D

    P304 should be cylinder #4 misfire. If the plugs have been changed, then it's elsewhere in the ignition system.
     
  5. Mar 5, 2012 at 10:07 AM
    #5
    damionseacat

    damionseacat [OP] Member

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    Seems this is going to get a bit more expensive. When do you decide to sell or repair??? Thanks for your input..:eek:
     
  6. Mar 5, 2012 at 11:38 AM
    #6
    jinxed77

    jinxed77 Well-Known Member

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    It's worthless i'll give you $100.00 for it.,I'm kidding. It may as simple as a cap or as serious as the motor. Have you considered just paying a shop to diagnose it?
     
  7. Mar 5, 2012 at 11:41 AM
    #7
    98tacoma27

    98tacoma27 is gooder 'en chicken Moderator

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    4 banger or 6 banger?
     
  8. Mar 5, 2012 at 12:42 PM
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    damionseacat

    damionseacat [OP] Member

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    Going to shop Wednesday.
     
  9. Mar 5, 2012 at 6:36 PM
    #9
    Rich91710

    Rich91710 Well-Known Member

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    +1. A P0304 is hardly a reason to sell unless you were planning to trade it in soon anyways.
    Depending on mileage/condition, an extracab V6 4x4 with 150k on it is worth $4-5k.
     
  10. Mar 5, 2012 at 6:43 PM
    #10
    hogeyphenogey

    hogeyphenogey Rotted frame = New Truck!

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    Could be a coil if you've done plugs and wires. That's what I'd try. Maybe swap coils and see if the misfire moves.
     
  11. Mar 5, 2012 at 7:32 PM
    #11
    joes06tacoma

    joes06tacoma Well-Known Member

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    A friend did this on his Audi recently. Swapped coils with one of the other cylinders, reset the computer, and the code moved to the other cylinder. At that point he KNEW what was wrong. No more guessing. Good stuff.

    If you can't figure it out, make sure you check the compression also. I hope that's not it, but have to check the expensive stuff too.

    My boss had a 3.4 4runner that had one fuel injector fail and cause a miss and trouble code. I'm not sure how the mechanic diagnosed it, but I know it took them awhile. Once they knew what was wrong it was fixed quickly and no more issues.
     
  12. Mar 6, 2012 at 4:54 AM
    #12
    jinxed77

    jinxed77 Well-Known Member

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    i don't think the 97 has individual coils. The OP stated he replaced "plug wires" so i'm assuming it has a distributor. Parts for the 4 cyl also shows a distributor cap which is a possibility. But if it did have COP ignition yeah you could move them.

    Anyway good luck damionseacat. Keep us posted when you find out what it is.
     
  13. Mar 6, 2012 at 5:06 AM
    #13
    98tacoma27

    98tacoma27 is gooder 'en chicken Moderator

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    The early coil packs on this motor fired two plugs and had coil wires. Some did have distributors though.

    [​IMG]

    [​IMG]
     
  14. Mar 6, 2012 at 4:55 PM
    #14
    damionseacat

    damionseacat [OP] Member

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    Thanks for the assistance guys
     
  15. Mar 6, 2012 at 5:52 PM
    #15
    Rich91710

    Rich91710 Well-Known Member

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    That narrows it down since a bad coil would generate two P030x codes.
     
  16. Mar 9, 2012 at 4:32 PM
    #16
    damionseacat

    damionseacat [OP] Member

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    Fuel injector on #4 needs to be replaced.
     
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