Misfire at High RPM

Discussion in 'Mazdaspeed 3 Troubleshooting' started by Lucas Higdon, Sep 10, 2021.

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  1. Lucas Higdon

    Lucas Higdon Greenie Member

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    I had a random misfire on stock hpfp internals, so I figured I needed better fuel flow, upgraded that everything is fine with it, still having the high RPM random misfire and it only misfires when Im done accelerating(slowing down) , Im going to change the spark plugs and clean the vaccum lines but didn't know if anyone had a answer to what could be causing this misfire.


    Should also mention that this code only appears at high rpm. ive cleared it and daily drove it for a week no hard acceleration, just normal driving, but the moment I go above 5k RPM is when it will throw the misfire code
     
    Last edited by a moderator: Sep 10, 2021
  2. L337TurboZ

    L337TurboZ World Class Truck Squatter Greenie Member

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    Check plug quality and plug gap. Set to 0.026-0.028
     
    L337TurboZ, via a Motorola device, Sep 10, 2021
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  3. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    Stretch the springs inside your plug boots while you have them off
     
    Easter Bunny, via a mobile device, Sep 10, 2021
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  4. Lucas Higdon

    Lucas Higdon Greenie Member

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    What does this exactly mean? Im still new to working on this car
     
    Lucas Higdon, via an iPhone, Sep 10, 2021
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  5. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    When you take the coils off turn them over there is a spring I side the boot which connects the coil to the plug give it a little tug to stretch it out and make sure it is making solid contact with the plug
     
    Easter Bunny, via a mobile device, Sep 10, 2021
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  6. Lucas Higdon

    Lucas Higdon Greenie Member

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    just finished doing this, founds some videos on youtube of it, super easy, also should mention I discovered my bypass valve had no gasket, would that cause issues?
     
  7. Raider

    Raider Administraider Administrator Platinum Member

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    A boost leak at minimum. Plugs are a start. Injector seals next.
     
    Raider, via an iPhone, Sep 11, 2021
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  8. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    Probably
     
    Easter Bunny, via a mobile device, Sep 11, 2021
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  9. Lucas Higdon

    Lucas Higdon Greenie Member

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    I will keep this in mind, I don't think its gonna be a seal problem tbh Im not having rough idle or hard starts or low rpm misfires, just very high rpm misfires unless im just wrong on the research ive done about our injector seals
     
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