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Thread: Help with 8 speed shift mapping

  1. #1
    Tuner in Training EVguy1's Avatar
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    Help with 8 speed shift mapping

    I'm trying to build a trans tune for my abortion of a truck. I had to start with something to get me on the road for a holiday trip last week end ended up with this.
    Rambo trans map Oct 7.PNG

    Now that I've been driving it a couple of days I need to make some changes and looking for a bit of guidance.
    It upshifts way too soon and downshifts way too late. I would also like it to not shift into 7 or 8 when at speeds below 40 MPH.
    I spent the morning trying to figure this out and reading some other posts on this and came up with the following but have not loaded it yet. I think by raising the 6-7 and 7-8 shift RPM it should not upshift into those gears early? I don't really know what an appropriate downshift spread is so it does not just downshift and then upshift shortly after. I mostly tow with this truck and engine MAX RPM is 3200 though peak torque is more in the 1600-2200 RPM range.
    Rambo trans map Oct 13.PNG

    Does it look like I'm heading in the right direction?

  2. #2
    This for an Ecodiesel?

  3. #3
    Tuner in Training EVguy1's Avatar
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    I stuck a Cummins ISB170 in my 2014 Ram 1500. Its basically a common rail 4BT. The trans is receiving RPM, TPS and torque from the Cummins CAN bus.

  4. #4
    Well the only thing I can offer you is a file from my EcoDiesel, That has a Tune on it that I Absolutely love from GDE. And seeing that our engines do make Peak TQ at similar areas. Might be worth a shot Copying and pasting these values in and see how it feels. Also this file has a Manual shift feature that makes the + - buttons on the steering wheel actually Hold the gear you're in (Autostick) instead of locking out whatever gear you set it to(Electronic Shift Range). I have never tried writing this file to another ZF 8HP70 before, Im curious if the AutoStick style shifting transfers over if it was flashed with "Write Entire", but i doubt it.

    Thats an Awesome swap BTW! Many have talked about doing it, but you're the first ive seen. Mind sharing some Pics of it?
    Sadly when my motor had an issue, I bought another EcoDiesel Engine and Installed it myself. Luckily the Bottom end is in perfect shape and plan on rebuilding it.
    Attached Files Attached Files
    Last edited by Smxtmpr34; 10-14-2021 at 05:41 PM.

  5. #5
    Tuner in Training EVguy1's Avatar
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    Thank you Smxtmpr34, I would not want to write entire since its not running through the RAM ECU but through a PCS module but it will give me a starting point to make my shifts better. Does it downshift better than the stock one?
    Here is a bit of a build thread.
    https://www.ramforum.com/threads/ram.../#post-2279970

  6. #6
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    That helped and I made a few changes to get my upshift RPM a bit higher especially at light throttle so it was not always upshifting when moving slow around town. I still wish it would downshift sooner instead of the feeling that its coasting since most of my driving is towing.
    I would like to understand a bit more about the downshift RPM settings, do I want to set them lower or higher to get it to downshift sooner?
    I assume the downshift RPM always wants to be lower than the upshift RPM for the same gear change. I don't know if anyone has time to look at this trans tune and make some suggestions?
    Sure appreciate any help I can get.
    Rambo trans Oct 9.hpt

  7. #7
    Tuner in Training EVguy1's Avatar
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    I suppose its more accurate to call it decel downshifting? Zero throttle when coming up to a stop light.
    It does a strange "hunting" thing when getting down around 30 mph, feels like its maybe converter locking and then unlocking over and over not harsh just repetitive.

  8. #8
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    Smxtmpr34,

    Is this trans tune for 3.55 gearing or 3.92?

    Thanks
    Last edited by Ecksor; 12-02-2021 at 02:19 AM.

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    are you trying to get more of an "engine braking" action during zero throttle deceleration ?

  10. #10
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    message me i tune diesels with 8 speeds all the time

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    would
    it be possible to load this on just the tcm ?

  12. #12
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    Its been a while since I last posted. Lots has been done to the truck. Upgraded to the Charger console shifter so I can use manual mode and I like the console shifter.
    I have a pretty good shift map figured out under acceleration and still playing with the decel part of it. I'm starting to look at TCC settings and wonder if a lower slip-lock setting will help with towing? The current settings are for the Hemi which is going to rev a lot higher than my 3000RPM Cummins.
    These are the current settings:
    Slip-unlock 720 720 780 780 780 780 780 780 780 780
    Unlock - slip 815 815 815 815 815 815 815 815 815 815
    Slip - lock 2100 2100 2100 2100 2100 2100 2100 825 825 825

    I'm thinking something closer to this?
    675 675 675 675 675 675 675 675 675 675
    725 725 725 725 725 725 725 725 725 725
    1800 1600 1600 1600 1600 1200 1200 825 825 825

    Am I venturing into dangerous territory? I don't want to get into changing pressures or anything that will potentially damage the trans, just baby steps at this point.

  13. #13
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    Quote Originally Posted by mike_ct View Post
    are you trying to get more of an "engine braking" action during zero throttle deceleration ?
    Yes, I would like more in tow mode which in my truck is Sport mode.