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Thread: DQ250 6-speed DSG Knowledgebase

  1. #1
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    DQ250 6-speed DSG Knowledgebase

    Collecting information as I come across it related to tuning the DQ250 DSG.

    Unfortunately I don't have much 'knowledge' to share at this point , but I am organizing what I have here.
    Last edited by MyGolfMK7; 05-28-2021 at 01:25 PM.

  2. #2
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    I have been tweaking my tune and found out that some of the DSG behavior can be modified by changing some parameters in the ECU calibration. There are some tables under TORQUE MANAGEMENT that relate to the transmission behavior, after changing some of them I felt less hesitation in the low RPM range, the transmission seems to be holding the revs a bit higher before going into the next gear, also downshifting come earlier. Perhaps someone can try this and confirm that I am not under the placebo effect.

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    Yeah, they go hand in hand. Since the ECU relates APP to torque request, and the TCU tune side bases shift points and other things based on requested/actual torque and APP. For a short time I had to run stock ECU tune with an OTS DSG tune and the shift points were really high and it was definitely "off".
    Last edited by aaronc7; 11-04-2020 at 08:00 PM.

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    Quote Originally Posted by aaronc7 View Post
    Yeah, that go hand in hand. Since the ECU related APP to torque request, and the TCU tune side bases shift points and other things based on requested/actual torque and APP. For a short time I had to run stock ECU tune with an OTS DSG tune and the shift points were really high and it was definitely "off".
    How do you fix that, do you mind elaborating a bit more?

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    First need to look at and understand how the shift logic works. The upshift table axis' are pedal position and basically "axle" torque. There are several ECU tables that alter the relationship between pedal position and requested torque, so that will directly affect the TCU side of things.

    I brought up my stock S3 tune for a random example... Let's say we're in in 3rd gear, between 2000rpm accelerating, with pedal position at 30%. In my torque request table, at this position it calls for 26-27% of max torque request. Max torque request in this gear, at this rpm range is 280 lb-ft... so it's requesting 73 lb-ft ultimately. When will we change gears? We then convert this to axle torque so we can see where we're at in the upshift tables. The effective gear ratio in 3rd gear on my car is ~6.25. So my axle torque is ~450 lb-ft. Going to my 3->4 upshift table, at 30% pedal position and ~450 lb-ft...we will shift right around 2600rpm.

    So if you increase increase you max torque request table, or pedal position vs torque request table on the ECU side and don't touch the DSG side.... you will naturally upshift at a higher rpm for a given pedal position, etc.

    I would just get your ECU tune solid, and then tweak DSG at the end for any fine tuning of shift points. I think you might end up chasing your tail a bit if you try to tweak both tables at the same time constantly.

    Hope that helps, I'm still learning as well.


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    That sound just about right, I will start with the ECU then.

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    From what I have logged it does not seem that the Trans Load axis is axle torque. The calculated axle torque results in a predicted upshift rpm that is much higher than shifting actually occurs at. Engine Torque does better at predicting the upshift rpm, though the engine torque value rarely exceeds the minimum axis value in the table.

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    Do you have any logs/examples? I will try to capture some today as well. Probably best to start from a stop and use constant pedal position to keep variables to a minimum.

    Any of you guys play around with increasing all the various torque limits, clutch pressure/ line pressure limits etc?

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    I got some good logs today, two different logs. One around 45 APP, the other around 60 APP.

    Like mentioned above...it definitely doesn't trend with "axle torque" like I thought and described in the Cobb documentation. But it's definitely not engine torque either. I tried just using the gear ratios to account for torque (not final drive), but that didn't make sense of it really either.

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    Here is the cobb tuning guide for reference. Really the only tuning guide i have seen for the DQ250s

    https://cobbtuning.atlassian.net/wik...G+Tuning+Guide

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    Quote Originally Posted by aaronc7 View Post
    Do you have any logs/examples? I will try to capture some today as well. Probably best to start from a stop and use constant pedal position to keep variables to a minimum.

    Any of you guys play around with increasing all the various torque limits, clutch pressure/ line pressure limits etc?
    I have been logging some data but initially I was mixing the Cobb Simulated Stock TCU tune with a custom ECU tune. I decided it I ought to try the Cobb Stage0 ECU tune to be as stock-like as I can, and I haven't had the chance yet to pick apart the results.

  12. #12
    Interesting. I felt like correcting torque with the final gear ratio got me in the ballpark. Based purely on driving feel, it seems like there is a modifier for either the y axis or the values based on steering angle and grade. Again right now this is just speculation though
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    Here's (hopefully) some good data that might be helpful to ID what's going on.

    Run 1 from a stop using around 44 accel pedal position, up to gear 6. I meant to do an even 40, but I didn't want to botch the run, but at least it's halfway between 40 and 50 columns.

    Run 2 was same thing, but 60 accel pedal position.

    Below is my normal shift tables and my own observations of when the shift occurs. This was done on a totally stock ECU and DSG tune.

    Run 1:
    2-3: 2366rpm, tq 115, pedal 44
    3-4: 2240rpm, tq 117, pedal 44
    4-5: 2330rpm. tq 123, pedal 44
    5-6: 2430rpm, tq 115, pedal 44

    Run 2:
    2-3: 2450rpm, tq 150, pedal 53
    3-4: 2800rpm, tq 180, pedal 59
    4-5: 2720rpm, tq 187, pedal 59
    5-6: 2930rpm, tq 185, pedal 59

    My trans ratios, followed by effective ratios if you factor in final drive

    1: 2.92---13.9284
    2: 1.83---8.7291
    3: 1.31---6.2487
    4: 0.97---4.6269
    5: 1.04---3.5776
    6: 0.81---2.7864
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  14. #14
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    Here is a DQ250 Tune you can copy or learn from, the choice is yours.

    Edit : Beautiful technical write-up on your site, I can appreciate your efforts!
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    Last edited by TewSlo; 11-13-2020 at 03:16 PM.

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    Quote Originally Posted by TewSlo View Post
    Here is a DQ250 Tune you can copy or learn from, the choice is yours.

    Edit : Beautiful technical write-up on your site, I can appreciate your efforts!
    Thanks! I'm curious about the changes you made to the downshift APP% axis. Was there a particular reason for the values you selected? I was thinking of increasing the number of axis values around the pedal position that I'd expect to see a transition from readily downshifting to not downshifting (allowing the turbo to spool up).

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    It seems that the 0% Pedal Position values at low load are what set the coasting downshift engine speed. At least I'm seeing a correlation between changing those values and the RPM that downshift occurs at.

    0_APP_Downshift.PNG

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    I have a question for all of you guys that are more knowledgeable than I am. My car started as a FWD model and later I added the AWD hardware, currently I am using a transmission with longer gear ratios as, as intended for a FWD car, but do you think that swapping to an AWD transmission with lower gear ratios will give the car a better acceleration from standstill, I still have the DSG from an R32 that I used as a donor, would it be possible to use the R32 mechatronic with a 2.0T engine?

  18. #18
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    Quote Originally Posted by LAGP View Post
    I have a question for all of you guys that are more knowledgeable than I am. My car started as a FWD model and later I added the AWD hardware, currently I am using a transmission with longer gear ratios as, as intended for a FWD car, but do you think that swapping to an AWD transmission with lower gear ratios will give the car a better acceleration from standstill, I still have the DSG from an R32 that I used as a donor, would it be possible to use the R32 mechatronic with a 2.0T engine?
    I am ading the stock TCU calibration file for the 3.2 VR6 DQ250 DSG:
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  19. #19
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    Here is a DQ250 tune I did for my 2017 S3 if anyone wants to check it out. Im interested on how low people are going on the shift times and the torque reduction. This tune is pretty solid, very happy with it on my S3. It makes about 450hp, shifts are quick and smooth. No clutch slip. Shifts feel better wide open throttle with less torque reduction but i dont know how far i can go there without damaging the trans, so i left it conservative.

    Thanks,
    Darin
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  20. #20
    Quote Originally Posted by DarinD View Post
    Here is a DQ250 tune I did for my 2017 S3 if anyone wants to check it out. Im interested on how low people are going on the shift times and the torque reduction. This tune is pretty solid, very happy with it on my S3. It makes about 450hp, shifts are quick and smooth. No clutch slip. Shifts feel better wide open throttle with less torque reduction but i dont know how far i can go there without damaging the trans, so i left it conservative.

    Thanks,
    Darin
    I've gone as low as 90ms in the Manual upshift table without issue (doesn't feel like anything is binding or slipping). I cannot really confirm that it is making the shift in that target time, Feels good though. I also dropped the off throttle section of the "Shift timing - General - Max Shift Time - Manual" Table. This seems to speed up the entire downshift process (Rev match, gear selection, and clutch engagement). Haven't added any line pressure or removed any torque management so far, but will try that soon.
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