97 astro dreadfull po300 misfire

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Thread: 97 astro dreadfull po300 misfire

  1. #1
    Walking
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    97 astro dreadfull po300 misfire

    Hello new here to the forum. I am haveing po300 problems. started off as a cyl 1 and 2 misfire, replaced coil, plugs, wires, cap and rotor (acdelco), maf, tps, distributor, checked for vaccum leak by spraying every inch of the motor, cyl 1 was misfireing at 96 misfires per cycle and cyl 2 was 79 misfires per cycle, now i have a cyl 3 misfire at 185 per cycle, checked fuel have 64 psi with key on and 55-60 with it running, also did a injector test and all the injector pressure to 65 and go to 30psi t the same time, replaced with new cam sensor, new egr reading on my scanner at 1500rpms my cam would go to -17 degrees so i resat the timing at 0 degrees and it seems to running a little worse. Starts with no trouble but has a small rumble seems like it has a radical cam , If you go to pull out i stumbles a bit but runs fine with higher rpm. misfire counter goes down between 20 and 65 at higher rpms
    check engine light flashes unless i am on the gas at around 12 1300 rpms and higher



    here the specs from my scanner,.

    rpm 700
    tps 0.57
    b1s1 495-600 MV fluctuates constantly
    B2B1 200-550 MV fluctuates constantly
    B1S3 200-740 MV fluctuates constantly
    A/F RATIO IS 14.7
    MAF 7.5
    BARO (KPA) 95
    MAP 2.05 V 49(KPA)
    COOLANT 94DEG CELSIUS
    INTAKE AIR 16 DEG CELSIUS 2.66V
    IAC 84
    DESIRED IAC 84
    DESIRED IDLE 650
    IGNITION 13.5 VOLTS
    MISFIRE CYL 3 184 PER CYCLE
    KNOCK 4.65
    SPARK ADVANCED 22
    KNOCK RETARD IS 0
    CAM RETARD 0
    CAM RETARD CHANGES TO -17 AROUND 1300 RPMS AND SLIGHT TO NO MISFIRES AFTER 1200 RPMS
    B2S1 SWITCHING FROM LEAN TO RICH CONSTANTLY
    egr 0.76
    Edit/Delete Message

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  3. #2
    6.2 Liter LS9 Supercharged V8 MrCritical's Avatar
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    Re: 97 astro dreadfull po300 misfire

    What is the fuel pressure spec at idle (high-low)?

  4. #3
    Walking
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    Re: 97 astro dreadfull po300 misfire

    i thought i heard a vacuum leak in the intake so i decided to tear t apart to find the the three cylinders that were misfiring ended up have junk in them hoping that replacing my spider will fix this issue

  5. #4
    Walking
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    Re: 97 astro dreadfull po300 misfire

    ok so after ripping everything apart i come to find someone changed the spyder already........... took it to a local shop they cleaned it n tested it it was fine put it in and still same thing cyl 3 misfire?????????? what next

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