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2014 Mustang Roush misfire

Discussion in 'Engine/Tuning' started by jamyzd39, Aug 13, 2018.

  1. jamyzd39

    jamyzd39 Member Established Member

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    2014 Roush stage 3 modded, JPC return style fuel system running on E85, Roush 110mm CAI, Kooks LT headers with off road H pipe, ID1000's, Steeda Heat Exchanger, BMR suspension ,Steeda Aluminum driveshaft, Mcleod RST clutch/lightweight steel flywheel w/SS clutch line, MGW race spec short shifter, VMP 67mm throttle body

    Anyways, This is what is happening. I had a misfire issue on Dyno. Plugs and O2 sensors changed. Still had misfire. Coils changed, crankshaft sensor pulled and wiped off, crank relearn performed. Kam reset done. Cylinders scoped and compression test done. No damage shown and everything is within specs. Data logs still show misfire at WOT, but no CEL's present.

    Anymore suggestion from anyone? Let me know if you want to see data logs. Thanks
     

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  2. PC03GT

    PC03GT Well-Known Member Established Member

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    Might be the o ring loose on the crankshaft position sensor
     
  3. twistedneck

    twistedneck Active Member Established Member

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    you mean you had a real misfire that you could hear and see or just the P030x code? If its the code good luck. I've had one for years on my 2012 ever since I put on the boss manifold (I now have the cobra jet intake). I first tuned it with headers and stock intake there was no light. Fast forward 6 months and got the boss intake installed - first light came on it was a P0302 then a bit later P0300 now it just alternates between them and yes I've moved the coils around, never went to limp mode either just throws a code. I then rebuilt half the engine and replaced the cams even.. oil pump gears etc. twice clutch relearn and new Ford racing timing wheel and both updated (o-ring added) and brand new crank triggers.

    Codes always come back. Checked a lot, new injectors, new O2 sensors, new more restricted F150 3.5L Turbo PCV valve, bigger catch can, new cam tune.

    It happened after I first got it tuned back in 2012. So it could be damage from a lean out maybe to a sensor or possibly just a phantom report from a sensor. I've road raced it, drag raced it, and beat on it in general with no issues.. hell if the engine light is OFF that looks strange to me. I can re-set the light and about 1 day later its back. even if I don't drive it hard and idle around, makes no difference.
     
  4. jamyzd39

    jamyzd39 Member Established Member

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    Misfires at WOT and is pulling timing. Yes you feel misfire around 6200 rpm. It is at shop now but I’ve tried everything I can think of and more. I think my intercooler pump failed, so I’m upgrading that and changing bypass valve. I’ll keep fingers crossed but I have low hopes at this point
     
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  5. Riddick

    Riddick MERICA Established Member

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    I know you changed the plugs but did you tighten up the gap on them? Could be something as simple as spark blow out.
     
  6. jamyzd39

    jamyzd39 Member Established Member

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    I wish it was simple....I have gapped at .032
     
  7. jamyzd39

    jamyzd39 Member Established Member

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    New plugs and coils. Unfortunately this issue has been going on for a while. It’s onlu misfiring at WOT. When I try to data log in 3rd it misfires at top of rpm around 6700 rpm and tuner said it’s also pulling timing.
     
  8. vortecd

    vortecd Well-Known Member Established Member

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    .032 can still be too wide on some cars. Some times with spark blowing out it will just stop pulling and not have a misfire so it may have nothing to do with the plugs. But for something easy to try gap down .025 to rule it out completely.

    I never went above .030 on any of my blower cars. You need to go real low just to see what happens and if it fixes you can open them up a little more
     
  9. vortecd

    vortecd Well-Known Member Established Member

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    Another thing, could it be knock? You may be getting a false knock that is pulling timing. I can't say I heard of a misfire pulling timing
     
  10. twistedneck

    twistedneck Active Member Established Member

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    exactly, you may be getting a vibration and false knock although you would have seen that in the data by now. if you take the boost way down does it still misfire at that rpm range?
     
  11. jamyzd39

    jamyzd39 Member Established Member

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    My car is at the shop, hopefully they will narrow it down. Their is two different reputable tuners working together on it. So I’ll let you guys know the results if they can figure it out. I’ve had issues with for quite some time. Currently there isn’t any knock issues but in the past there has been. It seemed I had knock on 93 octane but no issues once I switched the return style system and E85.
     
  12. vortecd

    vortecd Well-Known Member Established Member

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    I hate stupid issue like this that keep you up at night!
     
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  13. rhite95

    rhite95 Member Established Member

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    Hope you get this figured out !
     
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