black stuff coming out of exhaust

  • SATAN
    SATAN
    Senior Member
    • 6782

    #16
    Well, it is most likely not done doing whatever it was doing to fuck up. A bad O2 sensor will not cause you to get THAT BAD of gas mileage. 11 MGP is piss poor. Something else is definitely going wrong. When you unplugged the FPR hose from the intake manifold, I would think that would make the car run even richer that with it plugged in at idle. I HIGHLY DOUBT it is an injector problem. I too would suspect the MAF or the CHTS or the FPR. If you knew what your Fuel pressure was, that would be a good starting point. You can get a hose barb fitting for like $5 that a $20 autometer fuel pressure gauge will screw into. Put it on the line between the fuel rail and the FPR to get your reading. I don't remember what OEM pressure at idle is supposed to be but, your manual should tell you. I think it is slightly higher than normal at like 40 or 41 psi. Anyone remember?
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20… underway for summertime daily driver.
  • Andrew84zx
    Andrew84zx
    Senior Member
    • 1110

    #17
    Fuel pressure

    At idle Approximately

    kPa (kg/cm', psi) 206 (2 1.30)

    The moment accelerator
    pedal IS fully depressed Approximately

    kPa (kglcm'. psi) 255 (2 6.37)


    copied from fsm
    I hate wheel gap with a extreme passion

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  • SATAN
    SATAN
    Senior Member
    • 6782

    #18
    Andrew84zx wrote: Fuel pressure

    At idle Approximately

    kPa (kg/cm', psi) 206 (2 1.30)

    The moment accelerator
    pedal IS fully depressed Approximately

    kPa (kglcm'. psi) 255 (2 6.37)


    copied from fsm
    Ok, so base pressure is 37psi. I thought it was a little higher at 40 or 41. Guess not.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20… underway for summertime daily driver.
  • Andrew84zx
    Andrew84zx
    Senior Member
    • 1110

    #19
    i thought so aswell, but more like 45psi. learn something new everyday.
    I hate wheel gap with a extreme passion

    my build
    viewtopic.php?t=2755
    seller feedback
    viewtopic.php?f=18&t=10430