Results 1 to 8 of 8

Thread: Need help tuning my 08 G8GT 6L80 before doing engine

  1. #1
    Potential Tuner
    Join Date
    Dec 2018
    Posts
    3

    Need help tuning my 08 G8GT 6L80 before doing engine

    I got a one owner 08 G8GT a couple months ago with 67000 original miles. It has a CAI and muffler delete and that's it. I originally got a Diablosport i3 tuner but found it very limited on the tranny. I found that my son already had the HPTuner so we have been playing with it some. The biggest problem I am having is massive flare in 1-2 and 2-3 shifts at WOT. It runs right up to the rev limiter. It drives me crazy. I have turned off the DOD and done some small changes to the tranny but need some help from someone who has more experience with these than me. I have been doing some Harley fuel injection tuning but this car is something else. I wish I could just take the car and have everything done I want done but I am a disabled vet and living on a fixed government income sucks. I am just really happy to finally have the car though, after looking for 2 years. I hope that my tune posts here. If not, shoot me an email and tell me how to do it. Thanks.
    Nick King
    Attached Images Attached Images
    Attached Files Attached Files

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    7,193
    Sometimes I can get rid of the flare by adjusting a few of the pressure settings within the transmission parameters.

    Look for the base shift pressure upshift pattern x. You can try slowly increasing the values, like 3-5% at at time to try and get a quicker shift. I don't like to go crazy there through, not much over 15-20% increase.

    Next look at the on-coming pressure presets. Do the same thing, add like 5% to each shift. That table is labeled as 0,1,2 and from what I can come up with it uses more pressure as the load/rpms are higher but it does not give you exact specifics on it.

    Sometimes I even lower the shift torque factor by 10% as well.

    Anytime you do a pressure change on the transmission you must reset the learning on the transmission for the it to take. So after you make the changes, save the file, flash the tune in. Then before you start car open the VCM scanner and connect to the vehicle. Then select the vehicle controls/special function icon, go to the transmission tab and on the right will be a transmission reset and transmission preset that you can click on. Do reset, then preset and it will start learning to the new values. It may shift a little quirky at first but it's normal.

    Do not click the trans fast learn or anything like that though, just the reset/preset ones.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
    Potential Tuner
    Join Date
    Dec 2018
    Posts
    3
    Thanks, I will take a look at those. I also didn't know about the tranny reset to learn. That may be why the small changes I've made didn't feel any different. I will re-load my first tune and then do the reset/preset and check it again. Thanks for the quick reply. BTW, did you look at my tune and did you see anything off? Thanks.
    Nick

  4. #4
    It may seem obvious but I've seen several 6L80s over the years with issues almost exclusively caused by low fluid. they are a pain to fill, but fairly easy to check (if you haven't already). Overfill a small amount too - about half a quart or a little more if you plan on any 1/4 mile. Otherwise, pretty solid advice above.

  5. #5
    Advanced Tuner
    Join Date
    Feb 2015
    Location
    Perth, Australia
    Posts
    762
    try lowering the shift point or raising the rev limiter.

    you're asking for a complete shift 100rpm before fuel cut rev limiter.

    as for the shift itself, reducing commanded shift time and upping the "2" cell for oncoming pressure preset for the 1-2 and 2-3 shift will also help

  6. #6
    Potential Tuner
    Join Date
    Dec 2018
    Posts
    3

    Angry Still can't get rid of flare!

    I have made a massive improvement in the overall shift performance of my transmission but I cannot seem to get the damn flare out of it in the Manual mode at WOT 1-2. Can someone who knows what they are doing take a look at my tune or offer some exact information as to what I need to do?MyG8Tune4.3.hpt

  7. #7
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    7,193
    I can't help you there, I never use manual mode because it's often slower than leaving it in drive.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  8. #8
    Potential Tuner
    Join Date
    Jan 2019
    Posts
    1
    send me your email ill go over your trans settings and help you out