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Thread: 2021 Super Stock short shifting at 5000 rpm's at WOT

  1. 10-27-2021 #1
    BoostedGTA
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    Question 2021 Super Stock short shifting at 5000 rpm's at WOT

    2021 Challenger Super Stock with only 500 miles on it

    At the drag strip, the car short shifts significantly on the 1-2 shift at 5000 rpms. This happens whether I let the computer shift or if I use the paddle shifters (it doesn't care if I don't hit the upshift paddle, it will shift at 5000 on it's own in paddle mode). For those that don't know, Dodge increased the redline on the Super Stock's to 6400 rpm's (Redeye is 6300).

    At first I thought it was due to the 29.5" tall drag radials (factory tire height is 28"), but I'm told the trans shifts based on output shaft speed so it shouldn't matter. Next thought is that the TCM adaptives need to learn... If the car had never been WOT before without crazy wheelspin (on the street), then the first time at the track maybe it's anticipating all the wheelspin based on what it learned so far? I tried about 6-7 more WOT attempts to see if it would start changing, but it did not. Wondering if I should reset the adaptives and start all over. Then my last thought is wondering if Dodge changed the shift calibrations from 2020 to 2021 to try and cure the 1-2 shift "hiccup" that many experience. I'm currently waiting on my bypass cable to come in so I can read my stock file. I currently have the MPVI2+ for datalogging purposes only since I'm not ready to void my warranty by tuning it just yet.

    Any suggestions to help diagnose?
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  2. 10-28-2021 #2
    white1
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    Can you post the tune file as well?

    Stock and what you're running currently
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  3. 10-28-2021 #3
    shak3r
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    It would be helpful if you u log trans-centric PIDs such as these...

    trans pids.JPG
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  4. 10-28-2021 #4
    BoostedGTA
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    Quote Originally Posted by white1 View Post
    Can you post the tune file as well?

    Stock and what you're running currently
    Can't read my stock file until my bypass cable comes in.
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  5. 10-28-2021 #5
    BoostedGTA
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    Quote Originally Posted by shak3r View Post
    It would be helpful if you u log trans-centric PIDs such as these...

    trans pids.JPG
    I'll see if I can add those.
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  6. 10-28-2021 #6
    spoolboy
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    Yep, log shift ID channel and see what table it's in and verify shift output shaft speed.

    It could be due to one of the drivetrain protection strategies or traction control causing an upshift.
    If in doubt, multiply everything by 1.1.
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  7. 10-29-2021 #7
    white1
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    Quote Originally Posted by BoostedGTA View Post
    Can't read my stock file until my bypass cable comes in.
    I sometimes struggle with reading comprehension haha
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  8. 11-03-2021 #8
    BoostedGTA
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    My Super Stock 2021 tune file is attached finally... Still need to get out and do a datalog but that won't happen until next week. I'm also attaching a 2020 Super Stock file for comparison. Can anyone make any sense out of these 2 files? I got the 2020 file from a friend who says it's his stock 2020 file. Looks like a LOT of differences...
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  9. 11-04-2021 #9
    shak3r
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    Assuming your gear ratio is 3.09 the shift schedule somewhat jives w/ what your seeing, but logging your shift id is critical. I bet a trans tune would improve ETs but would not bet my warranty on it.

    As you said, a good bit of tweaks bet/ 20 & 21 models, some don't make sense (i.e. red/black key hp modes are opposite).

    ShiftSchedule.JPG
    Last edited by shak3r; 11-04-2021 at 05:25 PM.
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  10. 11-05-2021 #10
    Moparmatty
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    Quote Originally Posted by shak3r View Post
    Assuming your gear ratio is 3.09 the shift schedule somewhat jives w/ what your seeing, but logging your shift id is critical. I bet a trans tune would improve ETs but would not bet my warranty on it.

    As you said, a good bit of tweaks bet/ 20 & 21 models, some don't make sense (i.e. red/black key hp modes are opposite).

    ShiftSchedule.JPG
    Is that spread sheet one you have made up?
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  11. 11-05-2021 #11
    spoolboy
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    https://cdn.shopify.com/s/files/1/00...p?v=1600260580
    If in doubt, multiply everything by 1.1.
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  12. 11-05-2021 #12
    Moparmatty
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    Quote Originally Posted by spoolboy View Post
    https://cdn.shopify.com/s/files/1/00...p?v=1600260580
    Thanks.
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  13. 11-10-2021 #13
    DAVECS2
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    I assume the gear and tire size have been set correctly. hpt acanner can do it, also Tazer and other variants can too.
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  14. 05-23-2022 #14
    jhcasey
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    Hello shak3r...I'm familiar w/ the trans tuning info from the Dodge Transmission Guide and also somewhat familiar w/ the Super Stock now owning one and my previous 2020 Redeye w/ the notorious 1-2 hiccup. I've watched the in-car vid of BoostedGTA's 6.6 runs and compared the shift rpm to your calculated value. He has the 3.09 gear because that was the only gear Dodge put in the car and he was at WOT. From the calculator he should be shifting at almost 5800 but it's more like 5400. It's been quite a while since I looked at all the shift tables and there is a boat load of them but can you tell me which table you used for the Yellow shift pattern data input table. Knowing it would help to find where in the tune you would have to be to get a 5800 shift as compared to where he actually is once he gets the data. I ask because based on my street driving I suspect my 2022 is going to shift early also. And unless I can figure out how to get from one table to the next, it's going to take a tune to fix it! FYI- I have noticed on YouTube vids that at least one 2020 SS runs up to 6000+/- unfortunately it is not data logged so don't know the shift pattern. Thanks
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