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Thread: Trans shift spread sheet for NAG1/W5A580

  1. #1
    Tuner in Training
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    Mar 2016
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    Connecticut
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    Trans shift spread sheet for NAG1/W5A580

    I have had a bear of a time trying to get my head around the upshift / downshift points on a NAG1 in a 2012 Jeep wrangler. I am a novice tuner at best, and with individual tables for everything plus having to compare output shaft rpm I could not "see" the tune - it was more like throwing darts at the wall in a dark room.

    I did download the Tuning School spreadsheet and that was helpful, but it was a little too complicated and there were a few things I didn't like.

    So I created a new spreadsheet that allows me to visualize the up shift and downshift point on graphs. In the main tab (Sheet 1) First check your gear ratios, axle ratio and tire circumference, and adjust these values as needed. (you can see I have 4.10 axle, and a tire cir. 100.7) Next copy and past the output shaft rpm from your tune to each shift category (1-2 upshift, 2 -1 downshift, etc). You may also have to adjust the Throttle position data labels if yours are different. It will calculate the engine RPM and vehicle speed. After those are input check out the tabs/sheets at the bottom, there is a sheet for each shift/downshift with a graph of the upshift points vs downshift point.

    Take a look at the stock tune file 2 -3 shift. Why the heck would Daimler/Chrysler come up with such a terrible (looking anyway) shift strategy. And I can't for the life of me figure out why they have multiple TPS data labels with different values - For example TPS: 85, 85, 95, 95, 100. Those seem all but useless.

    You can see the trouble spots I have with my current tune I will make some adjustments and see how it works.

    Jeep NAG 1 trans tuning stock.xlsx

    Jeep NAG 1 trans tuning tune 003.xlsx

    Hope this is helpful for someone. I am thinking about adding a TCC line, I have to think that through a little.

  2. #2
    Advanced Tuner
    Join Date
    Nov 2019
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    227
    Neat spreadsheet!
    However, tuning this trans under part throttle conditions has been particularly painful especially in the Wranglers as you have already seen in one of my threads.
    https://forum.hptuners.com/showthrea...g-Table-Tuning

    Quote Originally Posted by clinter36 View Post
    Take a look at the stock tune file 2 -3 shift. Why the heck would Daimler/Chrysler come up with such a terrible (looking anyway) shift strategy. And I can't for the life of me figure out why they have multiple TPS data labels with different values - For example TPS: 85, 85, 95, 95, 100. Those seem all but useless.
    I believe these are scaled/labelled incorrectly by HP tuners. Others with access to hex editors such as winols show accelerator pedal breakpoints completely different to that of HP tuners when looking at the same tune file. This seems to be for both the upshift and downshift table breakpoints. The breakpoints as read by winols seem to be much more realistic and useful eg there are no multiple breakpoints with the same value.

  3. #3
    Tuner in Training
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    Interesting... I would love to hear HP tuners comment on this. Mine seems to be accurate and tunes rather true... that is to say it does what I am asking it. And I have issues right where the graph show - for example I had a 4-5 / 5-4 intersection and at just the right throttle it would attempt a shift and clunk and basically stay in the same gear (hence my reason for creating the spreadsheet to begin with).

    Maybe some are in German - lol.

    After spending much time staring at the graphs, the multiple data points make a little more sense. First remember this is graphed as speed on the vertical axis and throttle on the horizontal axis (which seems a little screwy to me, but that is how it is in HP, so I kept it the same). If you want to create a down shift point at a certain throttle position - lets say 80% - regardless of speed, you would want a vertical wall on the graph - such that regardless of speed, as you push throttle up, eventually it will hit the wall and ask for a shift. This would be graphed by two data points with the same throttle position with a lower speed and an upper speed - creating the vertical wall on the graph.

    I have a revised spreadsheet I will post shortly, I realized that many TPS fields dont update on subsequent sheets plus I added TCC curves.

  4. #4
    Advanced Tuner
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    Nov 2019
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    Quote Originally Posted by clinter36 View Post
    Mine seems to be accurate and tunes rather true... that is to say it does what I am asking it
    Now that's interesting! Do you have a data log that shows say the 1-4 shifts occurring as per the PT shift scheduling tables and includes the "upshift speed offset" parameter?

  5. #5
    Potential Tuner
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    Sep 2021
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    Tucson, AZ
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    Thanks for posting this information & spreadsheets. I want to modify a few shift parameters on my 2012 Grand Cherokee - the one that bothers me the most is the 5-4 downshift when pulling a hill on the interstate. I want it to hold 5th longer, rather that downshifting pre-maturely. But it seems these shift tables are different, in that these are the TPS positions that allow downshift under deceleration. Am I correct in that thinking?

    clinter36 - did you get your 4-5/5-4 issue resolved? Have you made an modification to your TCC settings? The curves on my stock tune are quite different between all of the gears. 2nd is especially odd, where the lockup speed drops between 25-35% TPS

    2nd Gear.JPG

    When I make a 2nd gear turn & get back on the throttle, the engine bogs down (assuming its the TC locking up) - I punch the throttle, and the vehicle will accelerate like it should. Seems to me that the line should be a rather consistent slope across the TPS range. Does your lockup pattern look anything like this?