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Thread: What is the correct steps/process when flashing a tune from the Tune Repository?

  1. #1
    Tuner in Training
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    Sep 2015
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    What is the correct steps/process when flashing a tune from the Tune Repository?

    I apologize if this is already clarified somewhere, I looked first.

    My primary concern is the correct process for Write Entire, VIN and VATS so my stock radio and OnStar still work afterward.

    I'm happy with my 'stock' tune, but wouldn't mind playing around with a GMS1 image (I've read it behaves differently, I'm okay with that.) Unfortunately, I'm not sure what the correct process is for flashing a GMS1 tune out of the tune repo. I assume people have done this successfully on the LNF (a 2008 Sky Red Line, in my case.)

    What is the process, if not this:

    1. Know how to tune your car.
    2. Read stock program from car, back it up. Cost: 2 credits.
    3. Locate a tune file in the tune repo for your exact year, make, model, engine, trans-type, etc.
    (For my 2008 Saturn Sky Red Line 2.0L Automatic Transmission this sorts out as 1401928147 from RotaryPiston.)
    4. Pull a number of similar tunes and compare them for inconsistencies, you will find inconsistencies. See Step 1.
    5. License Tune File (required to flash?) - Cost: 2 credits.
    6. "Write Entire" (with incorrect VIN) to Vehicle.
    7. Change VIN after "Write Entire" completes.
    8. Relink VATs after "Change VIN" completes.
    9. Turn on vehicle, Radio and On-Star (if equipped) to verify everything is working.
    10. "Read" program back off car, with corrected VIN Cost: 2 credits.

    Total Cost: 6 credits.

    Thanks in advance!
    Last edited by wilson0x4d; 01-25-2016 at 09:58 PM.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Why go through all of that when you can just copy stuff from another tune and make your own for free. Minus the first cost of 2 credits of course.

    It's a very bad idea to write any tune from the tune repository to your computer, the chances are very high that it may brick and you are shit out of luck.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    HPT Employee Engineer@HPT's Avatar
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    You should not flash a tune from repository. Just copy differences if you need to, as suggested.

  4. #4
    Tuner in Training
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    What I'm hearing is that I should go to a dealership and have them reprogram the ECU then read the GMS1 program off the ECU afterward using HPT because none of the tunes in the repo can be:

    Trusted?
    Written to an ECU with a different program?

    I'm trying to avoid the cost of a dealer flash for a "see how it feels" curiosity. My belief is that the program code of the GMS1 is different, but since I can't unpack the HPT file and put the program code through something like IDA Pro (for comparison) I don't know what differs between them. (Or, can we? Can HPT files be unpacked somehow? I'd even take a stab at hand modification if it's possible.)

    FWIW, I've done the compare and copy of tables, including updating Axis values even though I don't believe/know that it makes any difference whether you update Axis values or not. (Correct me if I'm wrong. It's because of this latter point I'm at all interested in writing a GMS1 tune to the car. The other is to determine if AT performance is different since HPT doesn't seem to offer transmission programming on these cars.)


    Again, Thanks

  5. #5
    Tuner in Training
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    I take it you've installed, or plan to install, the required sensors that come with GMS1 too?

  6. #6
    Senior Tuner cobaltssoverbooster's Avatar
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    the gms1 does not flash the tcm. customizing the axis values does nothing for your power output. it only aids in tuning ease. unfortunately starting out fresh as you are now you wont really see the benefit behind the axis changes until you have about a good year of testing with the program behind you.
    2000 Ford Mustang - Top Sportsman

  7. #7
    Advanced Tuner
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    Mar 2014
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    Not sure which car you have but on my Saturn Sky Redline, I'm able to tune the auto trans using HP Tuners Beta 2.25 version and it makes a big difference in performance. If you have an auto trans and don't adjust the TCM parameters, you might as well leave all of your rev limits in the ECM the same because the TCM will not allow you to rev any higher until you adjust the shift points.