p0304 nightmare

A

alwaysbrkn

Greenie N00B Member
Currently im throwing a misfire code for cylinder 4. the car idles fine and my afr is in the normal range idles at 14.55-14.85 when I go wot it ranges from 11-12. boost pressure at idle is normal and at wot I hit the pressure that I am tuned for, My hpfp pressure at idle is in the normal range and at wot its reaching targeted pressures for an upgraded hpfp, I am not experiencing any boost cuts whatsoever. Only thing that is different is my ltft is sitting at 10.61 during idle and when I am cruising it is reaching 18.xx my stft at idle was sitting at -3.61 which i guess isnt really a bad number considering its closeness to 0. I have also noticed that mpg has really gone to shit except when I am on highways the mpg is i would say pretty normal when cruising. I just changed all the spark plugs 6 days ago and gapped the to .026 and ive checked all my ignition coils. I cant tell if this is a leak or what, ive sprayed soapy solution on all vaccuum lines yet i still could not find any leaks. my gut is telling me injector seal but I have had a prooblem with seals before and i could smell gas from the bay but this time i dont smell any fuel. was trying to see if anyone had any recomendations on what to troubleshoot next (p.s. this car wants to see me stress out). I can post logs if need be.

Year/Make/Model:2010/mazda/mazdaspeed3
Mileage:130,xxx but replaced the motor at 106
Location: Deerfield Beach
Concern:missfire that i cant find
DTC's: p0304
Modifications: cobb sri and tip. autotech internals. catless downpipe. catback exhaust. upgraded engine mounts. fully tuned. everything else stock.
ECU/Tuning Software:accessport
Tuner: freektune
Is the concern intermittent?yes
Can you duplicate the concern?yes
Recent Repairs: changed the whole fuel pump assembly back in may 2021
Correction:
 
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Move the coil pack to a different cylinder and see. What injector seals did you use in the build and did you torque to 17 to 18 lbs? Also did you replace or get injectors cleaned then?
 
yea i’ve moved the coil packs to see if it would follow and it didn’t. i had gotten the injectors cleaned and used stock seals. i did do the proper torque but i it’s been exactly two years this september since i swapped the motor
 
I have seen leaking injectors cause a misfire. Local guy had a bad HPFP cause the random misfire! Obvious compression and leakdown testing are next.
 
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