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Thread: 2008 Pontiac G8 tune issues.

  1. #1
    Potential Tuner
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    Mar 2019
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    2008 Pontiac G8 tune issues.

    Hello all. I had my car tuned (2008 Pontiac G8 GT. Rotofab intake. 145,000 miles) by a "professional" that came highly recommended. Was initially happy with the tune and the performance of the engine and transmission. I called and asked him to make a few tweaks to the transmission tune and things got hairy from there. He shortened the shift time (not a technical term. I mean he made it shift faster) in the TUTD mode and I was very pleased with the results. After a few months of driving I started to get some flaring in my shifts and some slow lazy shifts. I also tried racing a few times and now my car will not break 139 mph. I am now back to my "stock" tune and needing help. Tunes attached for your viewing pleasure. Any help will be greatly appreciated!
    Attached Files Attached Files

  2. #2
    Tuner in Training
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    How is it shifting with stock tune?. sounds like it still has problems with stock tune.
    i'm not a tuner- a dealer tech- . since it was good for a couple months and now very bad even with stock tune = sounds like you burnt up your transmission. These transmissions can not handle too much fast shift abuse.Especially at higher mileages. Can you pull a sample of fluid? (under car- grab a small cup/glass and with engine off (and cold so you dont burn yourself when re installing plug) unscrew the level plug on the trans pan- pull not more than a couple of ounces to check (or you'll be needing to add after and that's harder).
    if its dark-black and has a god awfull smell- chances are you burnt up some clutches or damaged the torque. A tune can not repair mechanical failure.

  3. #3
    Potential Tuner
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    I live in the sticks and haven?t built my shop yet. I tried to get it up high enough to get under it to check. That didn?t turn out well. All I have to work off of is sandy dirt. The jack stands sunk and the car fell and it took me for ever to get them out. As for the shifting it shifts very well under full power with both tunes. But it flares crazy bad with custom tune under normal driving conditions. Does that help? That is why I feel it is in the tune.

  4. #4
    Advanced Tuner
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    Jan 2014
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    G8 owner here. Post tune and log files, please?
    Daily Driver= 2016 Infiniti Q50 Red Sport 400
    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, 7875, 4L80 coming together )
    Truck= 1995 K1500 ECSB 5.0 5-speed (Dusty...)

  5. #5
    just a few things. Your MAF curve sucks, Your PE table sucks, Your timing table kind of sucks, your final minimum spark sucks, your shift timing is way too fast, Your max line is too high, your on coming presets are stock. Did you pay someone to do this??? Do you have a wideband?? I need to help a fellow G8 owner.

  6. #6
    Advanced Tuner
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    I will take a look at the files later...

  7. #7
    Potential Tuner
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    Mar 2019
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    I apologize I have not responded to any of your responses. I am a fireman and deputy sheriff and this coronavirus stuff has been Unlike anything I?ve seen in my almost 24 years of service. I have to get my laptop set up to repost the tune file and log files. For some reason it will not let me get to the ones I posted already. Again thank you for the responses.
    Last edited by gibbsracin; 1 Week Ago at 10:00 AM. Reason: Misspelling

  8. #8
    Tuner
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    Feb 2020
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    Sounds like a Pat G tune or some other mail order type tune. I had similar issues with mail order tunes in the past. They tell you a wideband is not needed to tune your car. Well, obviously that's not true. I did the mail order tune before, too much is left on the table for what your paying for. Would never do it again IMO. I suspect they are only using fuel trims to dial in your fueling and adjusting your timing based on knock. I dont see how its possible to get the tune even close using those methods.