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Thread: ZF8, engine braking force configuration in TDI

  1. #1
    Tuner in Training
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    Sep 2020
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    ZF8, engine braking force configuration in TDI

    Good evening,

    I am working through 2016 Q5 3.0 TDI HPT file I pulled from it and was wondering how (if at all) to adjust engine breaking power / strength. It seems that in the stock settings, the engine break is barely noticeable , but I also know that the same engine with ASIN in VW Touareg had much more noticeable engine braking.

    I have been looking through all the tables, but have not found anything that would control engine brake process.

    Any thoughts on where these could be located?

    Thanks in advance !

  2. #2
    Tuner in Training
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    To add more information to this thread - thanks to the Scanner, I can tell that most of the time I am using Shift ID 6, which maps in Transmission Shift Pattern 6 (it seems I am not a very aggressive driver). The map is shown below

    Transmission map 6.PNG

    Now, using the transmission ratios for 8HP55 applicable to 2016 Q5 TDI

    Gear ratios.PNG

    I can calculate the RPMs for individual switching points (bottom table below, top one is just a copy of the map from Editor)

    Transmission map 6 converted.PNG

    I did the same for the downshift table

    Transmission map 6 converted downshift.PNG

    and now I am trying to make sense from it. For example, when in 8th gear and with accelerator at 20.1% position, when RPMs hit 1267, it seems to imply that the gear will be shifted back to 7, if I read the table above right. This does not seem to control the engine braking force or the point at which the gears start shifting down? Also, it seems to be vehicle speed independent and controlled by the shaft (engine) speed only?

  3. #3
    Advanced Tuner
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    I don't have a ZF8, but it's great to see some good Audi/VW content on here.

  4. #4
    Tuner in Training
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    Here is the look at the upshift table for stock
    Transmission map 6 rpms upshift original.PNG
    and updates I have done
    Transmission map 6 rpms upshift modified.PNG
    Since this is a TDI, I do not expect to be operating in 3k+ region anyway, so I did not make any changes there, leaving the table as stock. I smoothed the curves in low RPM region a bit, put 7>8 curve more inline with other curves to have smoother shifting even at high accelerator positions, and also lifted all curves for accelerator positions below 40% to get shifting a bit higher and avoid very low RPMs on higher gears.
    Does it look reasonable? Any comments / suggestions for the upshift curves for individual gears?

  5. #5
    Tuner EVguy1's Avatar
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    Feb 2021
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    Did you ever figure out how to add more engine braking?

  6. #6
    Quote Originally Posted by EVguy1 View Post
    Did you ever figure out how to add more engine braking?
    my guess is you would want to adjust tcc lock up if you wanted to engine brake