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Thread: Cross Counts, IAC, Duty Cycle - relevant comparison?

  1. #1
    Electronic Ignition!
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    Cross Counts, IAC, Duty Cycle - relevant comparison?

    I have two sets of data that I collected, each running a different SA map. If I go through them and look for equal lines based on TPS and RPM, the only differences between the sets (other than SA) is the O2 Cross Counts, Injector Duty Cycle and IAC Position. Are those relevant for evaluating whether one SA map is better or worse than the other?

    1227747 / $42

    Set 1
    TPS Voltage: 0.92
    RPM: 1450
    Spark Advance: 19
    O2 Cross Counts: 53
    MAP kPa: 58
    Injector Duty Cycle %: 5.79
    IAC Position: 97

    Set 2
    TPS Voltage: 0.92
    RPM: 1475
    Spark Advance: 27
    02 Cross Counts: 77
    MAP kPa: 57
    Injector Duty Cycle %: 5.70
    IAC Position: 92

    This is fairly consistent between the two sets. The higher SA set has higher O2 Cross Counts and a lower Injector Duty Cycle and IAC Position when comparing equivelant TPS/RPM data.
    1989 Suburban 350, 1227747 / $42
    - Dana 60 Front w/ ARB Locker
    - 14 Bolt Full-Floating Rear w/ Detroit Locker
    - LT285/75R17 Toyo A/T II on 17x8 American Mohave
    - 4" Tuff Country HD Springs (Rear)
    - 3" Tuff Country HD Springs (Front)

  2. #2
    EFI GearHead ! EagleMark's Avatar
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    Lower Duty Cycle, Lower MAP and Lower IAC counts all add up to more MPG! Nice work!

    Cross counts are not though. They just keep adding up to 255 I think then start again at 0 besides that once you apply the Spark Advance hack it puts Spark Advance in place of O2 sensor cross counts in data stream, your cross counts are wrong now...

    EDIT: That's a lot of spark advance, are you watching knock counts?
    DO NOT USE THE TPS % HACK FOR OTHER THEN IDLE STUFF!!! It takes place of knock counts and knock retard no longer works!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  3. #3
    Electronic Ignition!
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    Definitely watching the knock - I am only up to maybe 30-40% premium in the tank. There are more knock counts, but it's only about 40 after a 30 minute log vs. 20 on the lower SA log (I'm expecing 100+ if I get into trouble?). If I'm doing my math right, that 27 degrees of SA is coming from the 30 degree SA cell (the interpolation around that cell), minus the 9.84 warm bias, plus 3.16 degrees for EGR and 3.16 degrees for lean cruise.
    1989 Suburban 350, 1227747 / $42
    - Dana 60 Front w/ ARB Locker
    - 14 Bolt Full-Floating Rear w/ Detroit Locker
    - LT285/75R17 Toyo A/T II on 17x8 American Mohave
    - 4" Tuff Country HD Springs (Rear)
    - 3" Tuff Country HD Springs (Front)

  4. #4
    EFI GearHead ! EagleMark's Avatar
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    Math sounds right. Is Spark Advance same in data?

    I updated the XDF to make it easier, the Main Spark Advance table is actual, Warm Spark Bias removed by linking to location 0X15...
    Attached Files Attached Files

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  5. #5
    EFI GearHead ! EagleMark's Avatar
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    Spark Knock is tough to find in these old ECM. It's an accumulator. If you use the Knock History table and watch data played back from log, you can find exactly what cell it is coming from. Play data slow or pause it and use Shift + ] to move ahead one frame at a time or Shift + [ to go back one frame at a time.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  6. #6
    Electronic Ignition!
    Join Date
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    Oh cool - I'm going to try that, thanks!
    1989 Suburban 350, 1227747 / $42
    - Dana 60 Front w/ ARB Locker
    - 14 Bolt Full-Floating Rear w/ Detroit Locker
    - LT285/75R17 Toyo A/T II on 17x8 American Mohave
    - 4" Tuff Country HD Springs (Rear)
    - 3" Tuff Country HD Springs (Front)

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