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Thread: El Camino VERY harsh 1-2 shift at light throttle 5.3 / 4L80E

  1. #1
    Tuner in Training
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    harsh 1-2 shift at light throttle

    Issue resolved - Non tune related.
    Attached Files Attached Files
    Last edited by IG109; 01-18-2020 at 08:03 AM.
    My Garage:
    2013 Challenger R/T
    2013 Caprice PPV - Dad car

  2. #2
    Tuner in Training
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    Nobody has any ideas? I'm sure there's something I haven't read but I'd like to get this iron'd out
    My Garage:
    2013 Challenger R/T
    2013 Caprice PPV - Dad car

  3. #3
    Advanced Tuner
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    Are you sure the trans is stock?
    Daily Driver= 2003 BMW 330xi
    Weekend Cruiser= 2009 Pontiac G8 GT (Vararam, TSP LS3 N/A Stage 1, OBX, CTS-V converter, MagnaFlows w/ J-Pipes, 160 t-stat)
    Project Car= 1991 Chevrolet Camaro RS (LQ4 w/ Gen 4 Rods, LS3 heads, turbo...)
    Truck= 2007 Chevy Silverado 1500 LT LY5 4x4

  4. #4
    Im on my phone at the moment so i can't look at the tune but try logging calculated engine torque PID and seeing what its reading during the 1-2 shift and take 10 psi off your base shift pressure in that area.

    Its important to remember the shift pressures in the ECU only effect the "torque signal" of the transmission. I.e. the PC solenoid takes the place of the vacuum modulator. So it doesnt have the final "say" on line pressure, its only biasing the pressure regulation valve.

    So its possible if the trans has a shift kit in you'll never get the shifts to be as smooth as stock.

  5. #5
    Tuner in Training
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    Trans has a GM reman sticker. Helped remove it from an 06 3500 Van. Assume the telephone company didn't get HD2 kits in their transmissions.

    The issue seems to get more pronounced with added heat to the trans. Does that make any sense?
    My Garage:
    2013 Challenger R/T
    2013 Caprice PPV - Dad car

  6. #6
    Advanced Tuner
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    Jun 2015
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    It looks like it is that your tranny temp gauge or something is messed up. It shows that the temp is -38 degrees the whole time. You should also log engine delivered torque to see where you are on the different shift pressure maps.

  7. #7
    Tuner in Training
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    Quote Originally Posted by ryan_axberg View Post
    It looks like it is that your tranny temp gauge or something is messed up. It shows that the temp is -38 degrees the whole time. You should also log engine delivered torque to see where you are on the different shift pressure maps.
    Didn't even notice that.. good catch.
    My Garage:
    2013 Challenger R/T
    2013 Caprice PPV - Dad car

  8. #8
    Tuner in Training
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    Trans temp was a simple bent pin. No difference in shifting. Logged torque parameter and made sure shift timing was slower in that range. Literally no change in the way it shifts. I dont fully understand how to pull line pressure out of it at these conditions or even how to log what line pressure is during shifts.

  9. #9
    Quote Originally Posted by IG109 View Post
    Trans temp was a simple bent pin. No difference in shifting. Logged torque parameter and made sure shift timing was slower in that range. Literally no change in the way it shifts. I dont fully understand how to pull line pressure out of it at these conditions or even how to log what line pressure is during shifts.
    Stupid question, are you running this in speed density mode?

  10. #10
    Potential Tuner
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    Jul 2017
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    I think your problem is the torque converter is slipping. I have a 2006 Chevrolet 3500 with LQ4 with a Jasper rebuilt 4L80E and it suddenly started shifting so hard from 1st to 2nd that it was hurting my spine. I noticed that the transmission was not locking up in 3rd or 4th gear. I replaced the torque Converter and all is well now.

  11. #11
    Tuner in Training
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    Dec 2016
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    Try going in shit pressure and under up shift tab the 1-2 upshift table the numbers on the beginning put lower number like 2-10 that should make a big difference there cause what is there now is like 20 which is not stock

  12. #12
    What was your non tune related issue???? I'm trying to figure out a similar problem for a friend.