Having a P0300 issue after fixing a few problems

Discussion in 'Mazdaspeed 3 Troubleshooting' started by Bighern9999, Apr 13, 2022.

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  1. Bighern9999

    Bighern9999 Greenie Member

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    Good evening everyone, I just bought a speed 6. Got it for 2k and loving it but the problems started coming out. So I have the standard oil consumption problem, also had a p0192 for fuel rail sensor and p0300. Changed out the sensor and code went away, I cleaned the EGR assembly and tube for good measiure. I changed the spark plugs, checked the coils but might replace them too. So the issue now I have a P0300 again, I removed the HPFP and cleaned it and installed back on. Code went away then the misfire came back. Now this happen above halfway or full throttle, almost feels as if the it's choking and not getting enough fuel. I'm trying to use this as a daily, unfortunately I don't have a Cobb access port or anything besides the generic scanner. This is what was collected from the freeze frame data when the DTC was triggered.
    ECT (F) 177.8
    calculated load 59.2%
    STFT- 0%
    LTFT- 0%
    MAP- 52.6 (inHg)
    Eng RPM- 4022 rpm
    speed 34 mph
    spark advance (7.0 degrees)
    IAT (F)- 120.2
    MAF (lb/min) 18.0
    TPS- 42.7%
    Fuel pressure 1280.7 psi
    EGR command 0%
    evaporator command 0%
    It's been a while since I've been in the tuner community, this is my first turbo car too.
     
  2. jsilva

    jsilva Silver Member

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    Was the car having the ‘choking’ feeling when you got it or did it appear along with the codes? Did replacing the pressure sensor help, or did it start after replacing the sensor?

    It may be worthwhile to do a compression test.
     
  3. Bighern9999

    Bighern9999 Greenie Member

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    Hello, so it felt better since I got the Fuel rail pressure sensor, but feels like it lacks gas when going top end. I just bought a COBB access port and got it shipped next day. I got the data log sheet and here it is. My HPFP stays at 500 or so at idle, and only 1200 psi when throttled it. I think my HPFP may be bad or possibly the pressure relief valve.
     

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  4. jsilva

    jsilva Silver Member

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    Your log looks like 2 minutes of idling :) If you could post a log with the accelerator to the floor (maybe 10-20 seconds maximum for the log), I’m sure someone more knowledgeable than me could comment.
     
  5. Awafrican

    Awafrican Moderator Silver Member

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    If you're only seeing 1200 psi at higher rpm with throttle it could be the PRV yes, clean the ground and make sure it's tight by the hpfp, when the engine is hot do the PRV test.
     
    Awafrican, via a mobile device, Apr 15, 2022
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  6. Bighern9999

    Bighern9999 Greenie Member

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    @Awafrican , Here is the log with the car warmed up and under load. I'm confused, my o2 sensors are not adjusting they are stuck on -.16% both short and long term fuel trim. What else could be missing?
     

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    Last edited: Apr 15, 2022
  7. Bighern9999

    Bighern9999 Greenie Member

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    So I changed out the PRV and rebuilt the HPFP with auto tech internals upgrade. No more misfire and running good now. Thank you guys.
     
    Bighern9999, via an iPhone, Apr 29, 2022
    #7
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