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Thread: Holding REVs when changing Gear

  1. #1
    New Member
    Join Date
    Dec 2011

    Default Holding REVs when changing Gear

    I have fitted a 4.3l V6 from a 2005 Chevy astro into a 1945 army jeep. the astro was an auto but I have fitted a manual gearbox.
    I have been able to work out most things from searching the forum and have the jeep running fairly good.

    The only problem I have not been able to fix is, if revved over 2500 rpm when I depress the clutch to change gears the revs hang.
    I have played with the throttle cracker in gear and it is better but I am not sure I am on the right track.
    I also enabled and set up DFCO but this didn't change the hanging.

    so couple of questions - am I on the right track playing with the TC

    Do I need to add an input into PCM to tell it I am in gear

    Or do I need to add a clutch input.
    I have attached my tune file

    Thanks Darren
    Attached Files Attached Files

  2. #2
    Senior Member
    Join Date
    Jul 2005


    Have you tried a 4.3 manual transmission calibration? There shold be plenty of 4.3/manual transmission calibrations around.

    Do you have a VSS(Vehicle Speed Sensor) input to the PCM? That input is what tells the "brain" how fast the vehicle is moving and what it should tell teh engine to do.

    1997 rcsb stock L31 longblock, Marine Intake with 28# EV6 injectors, L35 2700 stall TC,Hooker LT's 2.007 60ft

  3. #3
    New Member
    Join Date
    Dec 2011


    Thanks Hog

    Yes I do have vss connected.
    I do have some manual tunes for the 4.3 but when comparing them to the tune I am using I can't see any difference that I thought would make a difference.

  4. #4
    Lifetime Member
    Join Date
    Mar 2006


    Just because there arent any visible differences doesnt mean there arent differences. There are ALWAYS differences between an auto and manual calibration. Im assuming since it's an 05 engine that it's a 1MB LS1B PCM, shouldnt be hard to find a 4.3L/manual OS and full flash it like hog suggested.
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

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