Need help with p0300

Discussion in 'Mazdaspeed 3 Troubleshooting' started by GhostMS3, May 25, 2019.

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  1. GhostMS3

    GhostMS3 Greenie N00B Member

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    I currently have the corksport Sri and tip, with autotech internals. No AP as yet, so still stock tune.
    I changed my plugs about 1000 miles ago to ngk one step colder set to .028. Code came on before the plug change. I also did the spring spring stretch on the coils. Now it is more frequent, and always on cold startup IMG_20190524_194902.jpg IMG_20190524_194909.jpg IMG_20190524_194921.jpg IMG_20190524_194935.jpg
    Below are some live data reads from my code reader. This is after a 40 minute drive, at idle. Thanks
    IMG_20190524_194902.jpg IMG_20190524_194909.jpg IMG_20190524_194921.jpg
     
    GhostMS3, via a mobile device, May 25, 2019
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  2. Rgurleyjr

    Rgurleyjr Greenie Member

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    How long was the sri on before the misfire code showed? Does the misfire code only come on at cold start and then go away?
     
    Rgurleyjr, via a mobile device, May 26, 2019
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  3. GhostMS3

    GhostMS3 Greenie N00B Member

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    Maybe a month after the Sri was installed. It comes on at cold start only, but it will stay on unless I clear it with my scanner. If I clear it right after start up, it stays off the rest if the day.
     
    GhostMS3, via a mobile device, May 26, 2019
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  4. Enki

    Enki Motorhead Platinum Member

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    I know this pertains more to the crank angle sensor, but try setting your MAF curve below 1.0 volts to 0.
     
  5. Sho

    Sho Silver Member

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    He has no tuning solution. OP should probably get one
     
    Sho, via a mobile device, May 26, 2019
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  6. Enki

    Enki Motorhead Platinum Member

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    I didn't see that.

    Also you shouldn't need step colder unless you're modded to high heaven and only running pump gas (no mix). What changed just before this started?
     
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  7. Rgurleyjr

    Rgurleyjr Greenie Member

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    Not all sris without tune cause problems. Corksport is factory maf size anyways.

    Don't think your intake is causing this. Does it run bad at all? Feel any misfire?
     
    Rgurleyjr, via a mobile device, May 26, 2019
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  8. Sho

    Sho Silver Member

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    If you bypass cold start (by starting the car with the gas pedal pushed in about a half inch and then letting off one the car starts and the rpm shoots up), will it not throw the code?

    If so, check for a vac leak to any of the lines running to the intake manifold. I used to throw a random misfire or a cyl 3 misfire on cold starts when the line from pcv to manifold had a little tear in it.
     
    Sho, via a mobile device, May 26, 2019
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  9. GhostMS3

    GhostMS3 Greenie N00B Member

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    It runs perfectly fine, doesn't feel like I'm getting any backfire. It really is just at startup.

    I will try giving a little gas at startup, and see if that helps. I also really need an AP
     
    GhostMS3, via a mobile device, May 26, 2019
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  10. davros

    davros Greenie Member

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    get rid of those one step colder plugs also
     
  11. _Mazdarati

    _Mazdarati I just want my car back Greenie Member

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    Why would getting rid of the plugs help?
     
    _Mazdarati, via a mobile device, Jun 4, 2019
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  12. Sho

    Sho Silver Member

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    They're unnecessary at his mod level. Especially considering he doesn't have any tuning solution.
     
    Sho, via a mobile device, Jun 4, 2019
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  13. Enki

    Enki Motorhead Platinum Member

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    You want as hot a plug as you can run without detonation to help keep the plugs clean (prevent fouling). Step colder plugs on a full e85 car tends to run like shit in general, as an example (Yeah I know you aren't full corn).

    There's a reason the factory plug temp is the way it is.
     
  14. GhostMS3

    GhostMS3 Greenie N00B Member

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    I switched the plugs out Thursday for stock range. Still getting the code, but I'm gonna let it sit for a couple power cycles and see if the ECU resets.
     
    GhostMS3, via a mobile device, Jun 4, 2019
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