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Thread: can somebody please tell me what is happening? short drive log and major miss

  1. #11
    Lifetime Member mvvette97's Avatar
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    well these are the Bosch O2s they sell at Napa. I had two new sensors I put in but it's the same. I have heard that these O2s don't work so well sometimes.

  2. #12
    Joe (Moderator) joecar's Avatar
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    I agree, your front NBO2's are switching too slow (slower than 2 times/second)... in some places it shows several seconds before they switch.

    Even when actual AFR is not stoich, the NBO2's switch quickly, their average voltage is what the PCM uses to determine the STFT's/LTFT's.

    Also, your MAP looks wrong... when throttle partly open MAP value dips below closed throttle MAP value.

    Also, why is IAT so high...?

    i.e. there may be 3 or more problems.
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  3. #13
    Lifetime Member mvvette97's Avatar
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    well what would cause the map to be wrong? As far as the O2s could it be just the Bosch sensors? As for the IAT I'm guessing it's high because of the under hood heat when it sets after I have drove it. It's been near 100 degrees here for about a week.

  4. #14
    Joe (Moderator) joecar's Avatar
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    I'm not sure exactly what your MAP is doing... check for airleaks.

  5. #15
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Vette..

    Where on your exhaust are your Narrow-Bands located? Do you have headers?
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  6. #16
    Joe (Moderator) joecar's Avatar
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    +1 which headers do you have...?


    Might want to test MAP sensor with a handheld vacuum pump while checking with scantool...

    Approximately: every 2 inHg increase in vacuum = 1 psi decrease in MAP = 7kPa decrease in MAP

  7. #17
    Lifetime Member mvvette97's Avatar
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    I have Pacesetter long tube headers so the O2s are just in front of the collector.

  8. #18
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Quote Originally Posted by mvvette97 View Post
    I have Pacesetter long tube headers so the O2s are just in front of the collector.
    Interesting. I have mine right before the cat...

    Wonder if that is an issue?
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  9. #19
    Joe (Moderator) joecar's Avatar
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    Those are steel headers...? Are they ceramic coated...?

    Uncoated steel will lose heat compared to stainless steel or coated steel or coated stainless.

    This may be what is happening... do you get any DTC's...?

  10. #20
    Lifetime Member mvvette97's Avatar
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    just uncoated steel headers. No codes as of yet

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