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Thread: GTP with 3.29 gear tuning help...

  1. #1
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    GTP with 3.29 gear tuning help...

    I have a built trans with 3.29 gear but have never changed the trans tune. The speedometer is correct, and listed as a 3.29 in the speedo tab, so I'm guessing the reluctor wheel was replaced when built. Had a 3200 stall convertor, but it was toasted so it was replaced with a stock GTP convertor. Not sure what the old one was, just know that it was smaller in diameter and blue. Not sure if the flywheel is stock, heard of people using a GT flywheel for some reason!?! The problem is a vibration under throttle, and it seems to lock up quickly and bog down mostly in 4th, also takes quite a bit of throttle to unlock. If I am passing a car and hit the gas it will stay locked unless I hit about 1/2 throttle then unlock. All suspension parts have been replaced on the front end to rule that out on the vibration. So my question is, I've heard of people using a stock GT tune when switching to 3.29 gear. Do you think this would help/hurt my problem, and which tabs do I need to change if this could fix my problem? Sorry for the long post, just want to get as much info out there as I can...

  2. #2
    Senior Tuner Russ K's Avatar
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    Read this thread; http://www.hptuners.com/forum/showth...highlight=3.69

    Also post your stock & modified tune. What size tires?

    Russ Kemp

  3. #3
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    Tire size is 225/55R17

    Just an fyi...I was told what was in the speedo tab was correct because they changed the relucter wheel. Obviously I will take whatever advise you give since what they said is not working, just thought I would throw that info out there...
    Attached Files Attached Files

  4. #4
    Senior Tuner Russ K's Avatar
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    Your file is tuner locked.

    Russ Kemp

  5. #5
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    I just pulled it off the car last night. How do I unlock it?

  6. #6
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    Nevermind...figured it out, I think.

  7. #7
    Senior Tuner Russ K's Avatar
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    The tire size was incorrectly reduced by the % difference between 3.29 & 3.69 gears. Try thses trans & speedo settings.

    Russ Kemp

  8. #8
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    I get this error when trying to open, "Unable to open file. Index was outside the bounds of array". After searching I guess I need a newer version but it's not on my customer page. I'll email support. Thanks for the help, I will let you know how it works when I get everything in order!

  9. #9
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    Ok, everything up and running, tune flashed. Shifts feel a little weird at light throttle, 30% throttle or above feels pretty good. Didn't do a wot run. Also when the TC locks it's like it hits a wall, really kicks hard and kinda bogs down. Still seems like it takes quite a bit of throttle to get it to unlock, and my speedo is off by 5 mph. I really appreciate the help, I know nothing about transmissions!! I attached the file I flashed.

  10. #10
    Senior Tuner Russ K's Avatar
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    What is your actual mph when the speedo reads 65 mph? Are you sure about your gear ratio & tire size?

    Also need a log of the trans calculated gear ratio while driving in 3rd gear, it should be 1.00. Are you getting a P0730 code?

    Russ Kemp

  11. #11
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    Mph - when GPS reads 65 Hud reads 73.

    Gears were said to be a 1" 3.29 GM chain-set from the original trans owner, and the re-builder but I really have no clue. I have to go by what they say because I know nothing about them. I do know the install was pushed off a few days because they ordered a different relucter wheel, but not sure if that changes anything. The tire size I originally quoted is correct.

    I am throwing a P0730 code now.

    I attached the scan of 3rd gear. I have also attached the current file flashed to my PCM. I changed the MAF tables due to a throttle body and MAF install. Not sure if it makes a difference, but thought I would let you know.

  12. #12
    Senior Tuner Russ K's Avatar
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    Ok, at 2100 RPM in 3rd gear with a 3.29 drive ratio, you should be actually going 50 mph, not 55-56 mph as per your scan. Note that your calculated gear is .875, not 1.00

    And I'm positive that you don't change the reluctor wheel when swapping sprockets. You need to reinstall the stock GTP reluctor wheel.

    Might be worth trying to set the speedo tab the same as a GT to see if the calculated gear ratio is 1.00 & the P0730 code clears.

    Russ Kemp
    Last edited by Russ K; 08-05-2012 at 08:48 PM.

  13. #13
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    Ok, should I leave everything else you changed the same? If it helps at all, looks like it might be a 34 tooth reluctor wheel. ZZP sells them for gear set changes, but I did read somewhere that someone changed their 34 tooth back to the 30 tooth for easier tuning. Not sure if that changes your advise at all, I will try the GT speedo tables.
    Last edited by 1quikgp; 08-05-2012 at 09:29 PM.

  14. #14
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    Update: So I changed to stock GT tables and my speedo was off by 10, GPS=65, HUD=75. The only way it is spot on right now is if the gear is set to 3.29 and the tire size is 23.00. 3rd gear was .984. I double checked my actual tires and they are 25.625. Is it possible with the reluctor wheel change the gear has to be set at 2.93 and my current tire size?

  15. #15
    Senior Tuner Russ K's Avatar
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    You can try it, but if the calculated gear isn't 1.00 in 3rd you will get the P0730 code that will cause issues with the trans.

    The other GTP's still used the stock reluctor when the sprockets were changed.

    ZZP caused a lot of trouble with a customer's 2000 GTP.

    Russ Kemp

  16. #16
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    Hey guys! Given teh last reply here was 2012, I'll step in and hijack for a few.

    Ross, I had my trans built for my MP112 setup, and hadn't had any issues until recently. Throwing a P0730 code. Changed the fluid and filter recently, and then hit the dyno. Somethings been off every since. Well, I think ever since.

    At times, when stopped, I'll go to pull away, the car will rev/slip, then lock up and go. It shifts hard (which I thought was normal, but I'm thinking it's not).

    Mods:

    GMR 1" chain & 3.29 gears
    ATI 3000 stall converter
    GMR Torsen Diff
    Plus all the other mechanical goodies and fresh sensors.

    Tires are 245-45-18 (26.7" by HPT calc)


    RUSS, do you have a trans config file I could get from you for scanning?

    Thanks in advance,

    Ross
    Last edited by 2000Falcon; 07-11-2013 at 09:50 PM.
    MP112 conversion.

    2000' Grand Prix GTP

  17. #17
    Senior Tuner Russ K's Avatar
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    Try scanning with this .cfg file. Make sure that the trans calculated gear ratio is 1.00 in 3rd gear.

    Russ Kemp
    Attached Files Attached Files

  18. #18
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    15 july trans2hwy.hplRAVEN tune June 11 2013.hpt15 july trans1 hwy.hpl
    Quote Originally Posted by Russ K View Post
    Try scanning with this .cfg file. Make sure that the trans calculated gear ratio is 1.00 in 3rd gear.

    Russ Kemp
    G'day Russ

    Attached are 2 short scans from my house, then on the highway for a while. Definitely something going on here. Also attached is my current tune.

    Look forward to hearing from you when you have a sec.

    Thanks!

    Ross
    MP112 conversion.

    2000' Grand Prix GTP

  19. #19
    Senior Tuner Russ K's Avatar
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    Just change the gear ratio to 3.69 as your calculated gear ratio in 3rd gear is 1.109. Your new tires are only .7% taller. I would just leave the tire size field at the stock value.

    Russ Kemp

  20. #20
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    Quote Originally Posted by Russ K View Post
    Just change the gear ratio to 3.69 as your calculated gear ratio in 3rd gear is 1.109. Your new tires are only .7% taller. I would just leave the tire size field at the stock value.

    Russ Kemp
    I'll go ahead and do that. Does anything have to be changed under the General Tab (speedo) for Final Drive Ratio? Even after I type in my tire size of 26.6" and gear ratio of 3.69, it still shows 1.121 in the field.

    Thanks Russ!

    Ross
    MP112 conversion.

    2000' Grand Prix GTP