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Thread: Surging spikes on dyno data curve

  1. #1
    Join Date
    Mar 2012
    Location
    michigan
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    6

    Surging spikes on dyno data curve

    I have a 01 sierra c3 which is awd. I had a custom tune done to it. On my dyno data sheet its showing surging spikes on my curve for torque and hp. I used a rwd dyno so I had to take my front driveshaft out. I know my transfer case has a 62/38 split. Was this surging caused by taking out the front driveshaft and making the computer freak out?

  2. #2
    Join Date
    Dec 2007
    Location
    Ponca City
    Posts
    1,606
    Mine was doing that while the converter was locked. The converter was slipping on mine
    Slowest in Oklahoma...

  3. #3
    Join Date
    Aug 2008
    Location
    mansfield texas
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    3,512
    Yes you cant do that with awd you can mess things up bad that way... the surges are the tires thinkin they are spinning and trying to transfer power forward...

  4. #4
    Join Date
    Dec 2007
    Location
    Ponca City
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    1,606
    Plenty of people pull the front ds for dyno time.
    Slowest in Oklahoma...

  5. #5
    Join Date
    Mar 2003
    Location
    San Antonio, TX
    Posts
    11,038
    I've never seen anyone hurt a tcase or front diff by pulling the front shaft, that wasn't causing the surge.

    i guess if the tc was trying to lock and slip that might do it.

    also, every dyno has a junky graph in raw data form, usually there's a filter enabled by default that makes the graph pretty for us.

    could have been a misfire or fuel issue.

    start with the basics.

    or tire spin.

  6. #6
    Join Date
    Aug 2008
    Location
    mansfield texas
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    3,512
    The trailblazer weirdos say dont it confused me at firsr too... glad i wasnt wrong in the first place... lets repost this on kurts fan page board

  7. #7
    Join Date
    Jan 2011
    Location
    Mcalester,okla.
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    565
    I had my awd truck dyno tuned with front shaft pulled with no problems other than wheel spin on the dyno

  8. #8
    Join Date
    Mar 2012
    Location
    michigan
    Posts
    6
    I already started with the basics. Its not tire spin. We checked the straps and they were really tight. For spark, I just changed my plugs and wires and everything was working as should. Checked fuel pressure and everything is good.

  9. #9
    Join Date
    Mar 2003
    Location
    San Antonio, TX
    Posts
    11,038
    we're having an issue with the spark and optical pickup loosing signal, could just be the dyno causing it.

  10. #10
    Join Date
    Sep 2008
    Location
    Arizona/Utah
    Posts
    3,939
    Where are you located in Michigan? I am moving to Grand Rapids in a few weeks.
    ECSB 2kSierra 2wd 4.8L-K&N-HPtuners-Calspeed LT's-Magnaflow-Tahoe20's-HankookRH06

    waiting to go in... 3.90s, 214/220cam

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