P0304 code - misfire in cylinder #4. Help.

Discussion in '95+ Gen Toyota Trucks' started by hodag, Dec 19, 2006.

  1. hodag

    hodag

    Messages:
    631
    On the wife's '99 4Runner (3.4, 5 spd, 122K miles) I am getting a P0304 code. Ran fine yesterday, drove all over town with no problems. She drove to work this morning and said it was hesitating and vibrating, yet no CE light. On the drive home tonight, same symptoms, then the CE light came on.

    When she got home I went to check it out. It definitely sounds like it is missing. Making a ffft, ffft, ffft sound from the exhaust. Pinging under load too. Went to AutoZone to pull the code. Came up with the P0304 and a message saying "The PCM has determined that a misfire has occured in cylinder #4."

    First of all, #4 should be on middle driver side correct? What would you guys check first? The plugs and wires are about 2 year old Densos. The coils are probably original. I did the timing belt replacement at 118K, and cleaned the MAF recently too.

    Thanks for any help.

    Hodag
    [​IMG] [​IMG] [​IMG]
  2. KliersLC

    KliersLC SILVER Star

    Messages:
    3,042
    Location:
    San Diego, CA
    Not sure about the location of number four, but it would be on the end, not the middle, cuz IIRC they count up one side and down the other.....but I could be wrong.

    I'd check to make sure all the wires are hooked up, they occasionally just come loose.

    Other than that, I am no help at all. My T has the same engine, but I have yet to work on the thing....

    You might try yotatech or pirate for this. More folks over there with these engines

    Good luck,

    Dan
  3. Poriomania

    Poriomania

    Messages:
    356
    Location:
    Chicago
    Tacoma territory is good as well. I have a link to the diagnostic manual online, but I'll have to get that sometime tomorrow when I can get that computer to work.
  4. Poriomania

    Poriomania

    Messages:
    356
    Location:
    Chicago
    Here's a little info
    codes1.jpg
  5. Poriomania

    Poriomania

    Messages:
    356
    Location:
    Chicago
  6. hodag

    hodag

    Messages:
    631
    Well, heres the story now. Just got in from changing plugs and wires. Number 4 plug was obviously the culprit. Very black and worn compared to the other 5 plugs. Went ahead and changed the wires too (I think they were original).

    The truck runs fine now, no ffft, ffft, ffft, no shudder and hesitation. Autozone was closed so I havent cleared the code yet.

    What would cause #4 plug to go bad? Faulty plug? Injector going bad? I guess at this point, Im just gonna drive it and wait to see if the problem arises again.

    Thanks for the help.

    Hodag
    [​IMG] [​IMG] [​IMG]
  7. O.D.B

    O.D.B

    Messages:
    18
    Location:
    Sonora, CA
    misfire po304

    If your coil packs are original , it could be that one pack is bad. one pack controls spark in two cylinders plus waste spark. Don't jump con clusions , stick with the basics.

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