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Thread: Misfire P0300

  1. #1
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    Misfire P0300

    So here lately ive been getting a misfire code p0300. Plugs look good gaped at.026. Car has been running strong and still does but the code only pops up after a WOT pull, dosent happen all the time and cant see anything in the logs that makes me believe its even misfiring but still green in this tuning department, The only thing i haven't tried is moving the coils around to see if they are the problem.. The logs shows that its only #7 and #8 cylinders that are misfiring with both having counts between 7-12 on each cylinder. The tune has been in the car for some time now and has never had this issue before so im not sure its the tune giving me issues but also the weather has moved into the winter temps now which im assuming will have effects to the current tune. AFR is good and everything looks normal in the logs as usual. Just looking for options on what to look for or maybe something that im missing. Thanks

    2015 Dodge Charger scat pack
    Whipple #9 Stock engine

  2. #2
    Tuner in Training guru1oftal's Avatar
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    If you have around 100k miles and stock cam/lifters it could be the early stages of a failed tappet/worn camshaft.
    Most of the ones I am aware of didn't have a noticeable miss early on but would set the code.
    Oil analysis or looking at lift can be used to verify this.

  3. #3
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    Have you tried swapping the injectors to see if the misfiring cylinders change?

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    Broken ring lands generally show-up as a P0300 before soon becoming very obvious

  5. #5
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    Could possibly be the land rings if Whipple #9 means 9 psi boost on stock 392 internals.

  6. #6
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    Didnt think about the injectors but i did have two on both banks with bad o rings could be that as well. I'm hoping its not the ring-lands but if it is 426 here we come!!

  7. #7
    Advanced Tuner coanan's Avatar
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    Quote Originally Posted by FstdodgeKY View Post
    I'm hoping its not the ring-lands but if it is 426 here we come!!
    I said the same thing if/when mine looses the lands. My stock RAM BGE is pushing 11.4 lbs boost. Maybe I'm not pushing it hard enough to do damage.
    13 Chrysler 300S, Stock 17 RAM 6.4 BGE with TSP Stage 4 boosted Cam, AIT 18% OD pulley, E-force 2.62 pulley(12.2 lbs boost),, Fastman 84+4 mm throttle body, 1 7/8 kooks long tubes w/hi-flow cats, 3" Magnaflow Cat-back, FTI 2800 stall, Trans by Hellraiser, Dings Racing valve body and tune, Getrag 3.73, Walbro 400LPH, DW 65# inj. aluminum rad. SRT fans. Brembo upgrade. Stage one MOPAR springs, XIX X39 22x9 +15 - 22x10.5 +22 with NITTO NT555 265/35R22 - 295/30R22

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    misfire drive.hplSTREET.hpthere is a log I did after making a few changes to the car. I did notice a few unusuall things. In a few spots the o2 sensors seem to be reading a different ends of the spectrum and also the misfires usually occour when I'm letting out of the throttle or when the car spins. Keep in mind the roads were wet when I made this log and hard to make any full pulls.

  9. #9
    Advanced Tuner coanan's Avatar
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    Quote Originally Posted by FstdodgeKY View Post
    misfire drive.hplSTREET.hpthere is a log I did after making a few changes to the car. I did notice a few unusuall things. In a few spots the o2 sensors seem to be reading a different ends of the spectrum and also the misfires usually occour when I'm letting out of the throttle or when the car spins. Keep in mind the roads were wet when I made this log and hard to make any full pulls.
    I'm not a pro tuner, so don't ask technical questions. It's little stuff I found messing with my tune. Sure are logging a lot of misfires. Looks like your leaning out (11.95) (I would think that's lean for a stock 6.4) the longer you stay in boost, starts out good though. Not sure what MAP 157 is in boost level, I have mine setup to show boost in log. Mines probable a little fat at 10.5ish, I'm running around 11.4lbs.
    Mine was doing the same thing, I had to increase fuel mass by lowering number in open loop cells, odd, you would think raising them would, but i had to lower numbers to keep from leaning out. I'm logging (stft +ltft) for NN tuning the inj PW. It will show cells you are in during open loop. instructions (https://forum.hptuners.com/showthrea...-spark-advance)
    You can also increase the MAP numbers in st/lt fuel graph to show more.

    Hope others with more knowledge will chime in and correct if I'm wrong on things.
    Last edited by coanan; 11-07-2019 at 04:48 PM.
    13 Chrysler 300S, Stock 17 RAM 6.4 BGE with TSP Stage 4 boosted Cam, AIT 18% OD pulley, E-force 2.62 pulley(12.2 lbs boost),, Fastman 84+4 mm throttle body, 1 7/8 kooks long tubes w/hi-flow cats, 3" Magnaflow Cat-back, FTI 2800 stall, Trans by Hellraiser, Dings Racing valve body and tune, Getrag 3.73, Walbro 400LPH, DW 65# inj. aluminum rad. SRT fans. Brembo upgrade. Stage one MOPAR springs, XIX X39 22x9 +15 - 22x10.5 +22 with NITTO NT555 265/35R22 - 295/30R22

  10. #10
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    Thanks conan. I am logging sft+lft. And I hitting around 8 # of boost. I'll look at adding some fuel up top and see if it helps.

  11. #11
    Advanced Tuner coanan's Avatar
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    Quote Originally Posted by FstdodgeKY View Post
    Thanks conan. I am logging sft+lft. And I hitting around 8 # of boost. I'll look at adding some fuel up top and see if it helps.
    I see the LT and ST logs. Did you read this, https://forum.hptuners.com/showthrea...-spark-advance. Helps dial in the inj for fueling, you have pretty high neg numbers through mid range
    13 Chrysler 300S, Stock 17 RAM 6.4 BGE with TSP Stage 4 boosted Cam, AIT 18% OD pulley, E-force 2.62 pulley(12.2 lbs boost),, Fastman 84+4 mm throttle body, 1 7/8 kooks long tubes w/hi-flow cats, 3" Magnaflow Cat-back, FTI 2800 stall, Trans by Hellraiser, Dings Racing valve body and tune, Getrag 3.73, Walbro 400LPH, DW 65# inj. aluminum rad. SRT fans. Brembo upgrade. Stage one MOPAR springs, XIX X39 22x9 +15 - 22x10.5 +22 with NITTO NT555 265/35R22 - 295/30R22

  12. #12
    borescope time.

  13. #13
    Advanced Tuner coanan's Avatar
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    Quote Originally Posted by Kmoney View Post
    borescope time.
    I'm thinking the same.
    13 Chrysler 300S, Stock 17 RAM 6.4 BGE with TSP Stage 4 boosted Cam, AIT 18% OD pulley, E-force 2.62 pulley(12.2 lbs boost),, Fastman 84+4 mm throttle body, 1 7/8 kooks long tubes w/hi-flow cats, 3" Magnaflow Cat-back, FTI 2800 stall, Trans by Hellraiser, Dings Racing valve body and tune, Getrag 3.73, Walbro 400LPH, DW 65# inj. aluminum rad. SRT fans. Brembo upgrade. Stage one MOPAR springs, XIX X39 22x9 +15 - 22x10.5 +22 with NITTO NT555 265/35R22 - 295/30R22

  14. #14
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    I'll have to get me one. any recommendations for borescope

  15. #15
    Advanced Tuner coanan's Avatar
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    Don't get the cheap Snap-on BK3000OR. I had to put a light in other sparkplug hole to boro mine.
    13 Chrysler 300S, Stock 17 RAM 6.4 BGE with TSP Stage 4 boosted Cam, AIT 18% OD pulley, E-force 2.62 pulley(12.2 lbs boost),, Fastman 84+4 mm throttle body, 1 7/8 kooks long tubes w/hi-flow cats, 3" Magnaflow Cat-back, FTI 2800 stall, Trans by Hellraiser, Dings Racing valve body and tune, Getrag 3.73, Walbro 400LPH, DW 65# inj. aluminum rad. SRT fans. Brembo upgrade. Stage one MOPAR springs, XIX X39 22x9 +15 - 22x10.5 +22 with NITTO NT555 265/35R22 - 295/30R22

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  17. #17
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    I did scope the clyinder and didnt find any evidence of bad ringlands and everything looked good and surprisingly clean as well. Guess I'll look at the tune and see what I can do there.

  18. #18
    My car is a 2015 and I recently had #3 coil pack die on me. P0300 code and it finally popped a secondary circuit code for #3.

    It would run fine at PT, but would stutter and miss badly at WOT. Started very abruptly after my switch to ethanol.

    A new coil pack fixed it.