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Thread: 09 G8GT 6L80E shifting early

  1. #1
    Tuner 01 MidMet WS6's Avatar
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    09 G8GT 6L80E shifting early

    I have a 09 G8 GT that has an issue short shifting the 3-4 shift. At roughly 93mph the car will shift from 3rd directly into 5th gear. If you use the TUTD to put it in 4th gear it will also try to shift into 5th at around 100mph. It doesn't do it all the time but when it does it is almost always at 93-94 mph.

    The car has a LSA blower, heads, cam, stock bottom end, flex fuel with a stock 6L80 and a LSA converter.

    I included the tune file, scan, screenshot and config. Any ideas or any help would be very much appreciated!

    Newest OS, LSA blower, PD cam, ZL1 converter, ID1000's, E85, full flex.hpt

    trans shift into 5th.hpl

    LSA,LS9 Config flex fuel.cfg

    Brandon shift into 5th.PNG
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  2. #2
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    Can you log your trans temps? Your HOT shift points match exactly what the log is showing. I think your trans is overheating. But you cant tell without logging the temps. And after looking at your log again, 5th gear is slipping a lot. You have no RPM drop when the trans goes to 5th and the slip RPM is almost 3000 RPM. Might be time for a trans...
    Last edited by jaydubb71; 06-10-2015 at 05:01 PM.

  3. #3
    Tuner 01 MidMet WS6's Avatar
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    Quote Originally Posted by jaydubb71 View Post
    Can you log your trans temps? Your HOT shift points match exactly what the log is showing. I think your trans is overheating. But you cant tell without logging the temps. And after looking at your log again, 5th gear is slipping a lot. You have no RPM drop when the trans goes to 5th and the slip RPM is almost 3000 RPM. Might be time for a trans...
    I did not log transmission fluid temperatures on this one. On a previous tune file I matched the hot shift speed with Normal and Pattern A and it still did it. To back up the orignial tune was a mail order tune that I wiped clean with a new stock GM ECM and TCM files. I then worked off of them to end up with what I have here.

    As for the slip amount the transmission commands 5th but takes a while to apply 4th and then 5th. I am assuming if you keep into the throttle it will make the 5th gear shift but I let out as soon as you feel it shift ealy.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  4. #4
    I have been having the same issue with the TCM skipping 4th after a tune and short shifting. I have been tuning the G8's, Camaros, Vette's, Denali's and 6L80e GM's since 2009 but have noticed the issue since using 2.24. Not claiming there is an issue but there is something that is limiting 4th gear shifts under power that is fairly new. I contact Bill and he said I was the only person reporting the issue. Pat G was tuning a car that was previously tuned with HP Tuners and is having the same issue. There is nothing in the Trans tables that shows a "WOT skip-shift" but the TCM when logging shows 3rd then 5th but will go thru 4th all while short-shifting out of 3rd. To me there is a TM table missing and it is a max-torque value vs rpm vs gear that is causing it but could be something else. It isn't temperture related or due to RPM or mph not being set high enough in all the cases that I have had recently using the 2.24. I have even set 3-4 shift to 318mph and 8192 rpm and it still will short shift in manual mode.

    My guess would be to try manipulating the Tq calculations lower under engine TM to see if you can keep the calculated values low enough to avoid it short shifting but hope it wont burn up the trans in the process. Calculated TQ =shift pressure......

    I'm open to suggestions but have tried 50+ different variations on over a dozen cars with three different versions of 2.24....
    Rick Crawford
    2009 Pontiac G8GT
    11.65 @118.55 1.72 60ft DoD cam, 2600 stall, Crawford ported heads and intake, stock wheels and BFG-KDW tires
    9.95 @134.9 388, 3.45 gear, stock 6L80e ALL Motor!!
    [email protected] 417 LSA Blower-Only, 6L80e, 3.45

  5. #5
    Senior Tuner DSteck's Avatar
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    Add Trans Shift Mode (I think that's the name) to your log.

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  6. #6
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    new maf.cfgHave you actually logged it to see it do it?

    Here is a good logger i use on the A6
    https://www.facebook.com/tuningbyshanehinds
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  7. #7
    Tuner 01 MidMet WS6's Avatar
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    Quote Originally Posted by DSteck View Post
    Add Trans Shift Mode (I think that's the name) to your log.
    Added to the new config, see below

    Quote Originally Posted by G8-4-speed View Post
    I have been having the same issue with the TCM skipping 4th after a tune and short shifting. I have been tuning the G8's, Camaros, Vette's, Denali's and 6L80e GM's since 2009 but have noticed the issue since using 2.24. Not claiming there is an issue but there is something that is limiting 4th gear shifts under power that is fairly new. I contact Bill and he said I was the only person reporting the issue. Pat G was tuning a car that was previously tuned with HP Tuners and is having the same issue. There is nothing in the Trans tables that shows a "WOT skip-shift" but the TCM when logging shows 3rd then 5th but will go thru 4th all while short-shifting out of 3rd. To me there is a TM table missing and it is a max-torque value vs rpm vs gear that is causing it but could be something else. It isn't temperture related or due to RPM or mph not being set high enough in all the cases that I have had recently using the 2.24. I have even set 3-4 shift to 318mph and 8192 rpm and it still will short shift in manual mode.

    My guess would be to try manipulating the Tq calculations lower under engine TM to see if you can keep the calculated values low enough to avoid it short shifting but hope it wont burn up the trans in the process. Calculated TQ =shift pressure......

    I'm open to suggestions but have tried 50+ different variations on over a dozen cars with three different versions of 2.24....
    I have seen a couple unique shifting issues that did not line up with what the tune was requesting as well. We will see what happens with this one, I am going to load another completely stock trans tune file into it with the MDI and see what happens.

    Quote Originally Posted by 04blackgmc View Post
    new maf.cfgHave you actually logged it to see it do it?

    Here is a good logger i use on the A6
    I have actually logged it, see post below using the config you supplied.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  8. #8
    Tuner 01 MidMet WS6's Avatar
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    So here is a WOT run, on this run I started with the car in TUTD 3rd gear and after going WOT I shifted it into normal mode. DSteck you can see the Trans Shift Mode change from TUTD to WOT Normal. For those that do not want to take a look into the tune file WOT Normal shift requests for 3-4 are 114 MPH @ 6600 RPM and 4-5 is 144 MPH and 6600 RPM.

    I attached the tune file, data log, config and a couple screenshots to help out. I really think this is a software issue but we will see.

    Brandon shift into 5th, new config.PNG

    Brandon shift into 5th, tune tables.PNG

    MAF,VE,Trans.cfg

    CJTuned newest OS, LSA blower, PD cam, ZL1 converter, ID1000's, E85, full flex.hpt
    Last edited by 01 MidMet WS6; 06-23-2015 at 09:47 AM.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  9. #9
    Tuner 01 MidMet WS6's Avatar
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    Things are improving

    Update: I flashed the TCM only with the MDI using a stock new GM file and drove it completely unchanged from stock. It shifts through all the gears exactly like it should. I did include the scan data and a screenshot.

    So my concern now is that if I edit the file it will corrupt and I will be starting from scratch again. What are everyones thoughts on downloading an early version of 2.23 and working off of that? It looks like that is going to be my best bet at this point?

    Successful shift.PNG

    Successful shift.hpl
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  10. #10
    Senior Tuner DSteck's Avatar
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    Update your 2.24, read the file, and begin changing one thing at a time.

    DSX Tuning - Authorized HP Tuners Dealer
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  11. #11
    Tuner 01 MidMet WS6's Avatar
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    Quote Originally Posted by DSteck View Post
    Update your 2.24, read the file, and begin changing one thing at a time.
    Working on that right now, we will see how things go.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  12. #12
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    Any updates on your progress?

  13. #13
    I never had issues with short shifting using the 2.23 Beta....I have 20 guys that never had an issue before that are all shifting early now with 2.24. OEM trans tune and leaving TUTD stock seem to be the only way to avoid the problem. Once you adjust it, it corrupts, and going back to stock settings using HP Tuners doesn't fix the problem. The issue has shown up on everything from a 2012 Denali, 10-12 Camaro, 08-up G8, ect.

    Shane, adjust TUTD on tha G8 your working on and do a highway pull starting in third (since it will probably spin second or anything under 70 mph)and see if it short-shifts and goes straight to 5th. It will probably go thru 4th but the table display goes 3rd to 5th and wont even show 4th.
    Rick Crawford
    2009 Pontiac G8GT
    11.65 @118.55 1.72 60ft DoD cam, 2600 stall, Crawford ported heads and intake, stock wheels and BFG-KDW tires
    9.95 @134.9 388, 3.45 gear, stock 6L80e ALL Motor!!
    [email protected] 417 LSA Blower-Only, 6L80e, 3.45

  14. #14
    Tuner 01 MidMet WS6's Avatar
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    Quote Originally Posted by fixem2 View Post
    Any updates on your progress?
    Yes, I worked off the stock tune with the newest version of 2.24 and was able to make it work as needed. Not sure what adjustment was made that prevented it from working in the first place but the customer is happy and the car is working very well.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  15. #15
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    Funny thing I have a few cars i''ve emailed tuned that have this issue and some that dont. Did a local G8 last week and didn't do the 3-5 shift.
    https://www.facebook.com/tuningbyshanehinds
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    2009 G8 GT [email protected] 1.60 - Sold
    2008 A6 LS3 C6 Cammed [email protected] 1.44 Sold
    2013 CTSV wagon 9.21@151
    2015 C7Z bolt ons 10.0

  16. #16
    Tuner 01 MidMet WS6's Avatar
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    Quote Originally Posted by G8-4-speed View Post
    I never had issues with short shifting using the 2.23 Beta....I have 20 guys that never had an issue before that are all shifting early now with 2.24. OEM trans tune and leaving TUTD stock seem to be the only way to avoid the problem. Once you adjust it, it corrupts, and going back to stock settings using HP Tuners doesn't fix the problem. The issue has shown up on everything from a 2012 Denali, 10-12 Camaro, 08-up G8, ect.

    Shane, adjust TUTD on tha G8 your working on and do a highway pull starting in third (since it will probably spin second or anything under 70 mph)and see if it short-shifts and goes straight to 5th. It will probably go thru 4th but the table display goes 3rd to 5th and wont even show 4th.
    Rick, I was able to adjust the TUTD tables without issue.

    This is Carl, not Shane.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  17. #17
    Tuner 01 MidMet WS6's Avatar
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    Quote Originally Posted by 04blackgmc View Post
    Funny thing I have a few cars i''ve emailed tuned that have this issue and some that dont. Did a local G8 last week and didn't do the 3-5 shift.
    I have done plenty that have not had issues, not really sure what definitively it is that corrupts the file and why it only effects certain cars.

    Similarly I did a segment swap for a 4L80 in the most recent beta last week and that had all sorts of WOT issues as well. Switched back to a known good OS and rebuilt a tune for it and all was good.
    01 WS6-M6, PRC Stage 2.5 5.3's, MS4, Kooks 1 3/4", custom built full true duals w/ X-pipe, SLP lid, tuned via HPTuners

  18. #18
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    Just want to follow this thread i"m having the same issue.

  19. #19
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    I'll go make a WOT pull to 4th tommorow for you guys and see if my cars does the same thing (modded 09 G8 GT). It was shifting fine at the track but I just uploaded new tune with higher shifts points.

  20. #20
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    Start in 2nd or 3rd then let it shift through.