DSG slipping?

[yeahforbes]

Hey all, I've been EQT tuned for 700 miles now (ECU+TCU), and it's great except for a DSG issue I've been having. I want to be very careful not to blame the tune if it's unrelated, but I had absolutely no DSG issues the entire time I've owned the vehicle until tuning, and then the issues started immediately, day 1, before I even had an EQT DSG file and had to flash the Cobb OEM+ file. I have driven exclusively DSG cars since 2014 and I am very aware of its quirks, so please don't take this as a generic "why are DSGs slow sometimes" kind of question.

I'm not sure what the proper terminology is (false neutral, clutch slippage, etc.) but hopefully this log will help us figure it out. Whatever it is, it's not just a delay as you might encounter when the DSG guessed wrong and pre-selected a different gear than is being requested. It has happened about a dozen times so far, in just 700 miles and each time I feel like it's dying a little more.

I finally caught it while logging. Check out this log on datazap where you'll see that I have zoomed into approximately 290 sec to 310 sec. The scenario is that I'm cruising in top gear, and I let off the gas completely for a downhill. It's a steep downhill followed by a curve so engine braking is called for. Here are the points of interest, with ZERO throttle throughout each one:

296.11 - manual downshift 6>5, rpm blips from 1888 to 2336 over 0.26 sec = OK
296.42 - manual downshift 5>4, rpm blips from 2336 to 3040 over 0.34 sec = OK
297.14 - manual downshift 4>3, rpm flounders from 2976 to 3616 over 1.78 sec = BAD

That 1.78 second downshift is the problem which has happened about a dozen times. Most of the time it's actually when going down to 2nd, but this time it was when going down to 3rd. One time it even happened going down to 1st (but I don't make a habit of aggressive shifts into 1st, of course) and I think it even happened in 4th one time. The point is, it's not associated with a single gear.

In this case, I was totally off the gas so I only noticed due to the lack of immediate engine braking (and seeing the tach reveal the sluggish blip). In other cases, I get on the throttle when it's happening and it just revs almost as freely as if I was in neutral -- a scary moment.

Currently around 31k. Is this the sort of thing that a DSG service could clear up? I did the DSG Default Settings after about half of them, and it didn't help. I can try the other calibrations after I obtain a repair manual.

 

[Ed @ EQT]

Run through each item in the DSG service menu on the AP. Do them one by one and cycle ignition each time. Finish off with the default settings and the clutch learn. Make sure everything is up to temp before doing this. Once that's done, take it for a normal drive for 15-20 minutes (stop and go is best). Leave it in D for this drive to allow the TCU to relearn.

Otherwise, you should do an actual DSG service at this point as well.

-- Ed

 

[yeahforbes]

Thanks @Ed @ EQT, just ran through the process after a nice 90min of driving. Here are some questions/comments.

1. When you said "cycle ignition each time" do you mean starting/stopping the engine, or just going between key-off and key-on without starting the engine? The AP's on-screen instructions when doing each item actually specify key off for 5-10 sec and then key-on (not engine on) so I wasn't sure if you are suggesting additional cycles beyond that, or no. Since I wasn't sure, I did a full start/stop of the engine between each.
2. When I tried doing the Clutch Touchpoint Calibration, the AP said "ERROR: Vehicle requires additional driving to reset learning parameters before attempting again." So I went for a little drive... maybe 5-10min. All good after that.
3. I did not perform the last 2 procedures ("Reset CAN Info to Default" and "Reset Selector Position Use") because you said to finish with the clutch learn. But you also said to run through each item, so are you saying to skip those or do them?

 

[Ed @ EQT]

Thanks @Ed @ EQT, just ran through the process after a nice 90min of driving. Here are some questions/comments.

1. When you said "cycle ignition each time" do you mean starting/stopping the engine, or just going between key-off and key-on without starting the engine? The AP's on-screen instructions when doing each item actually specify key off for 5-10 sec and then key-on (not engine on) so I wasn't sure if you are suggesting additional cycles beyond that, or no. Since I wasn't sure, I did a full start/stop of the engine between each.
2. When I tried doing the Clutch Touchpoint Calibration, the AP said "ERROR: Vehicle requires additional driving to reset learning parameters before attempting again." So I went for a little drive... maybe 5-10min. All good after that.
3. I did not perform the last 2 procedures ("Reset CAN Info to Default" and "Reset Selector Position Use") because you said to finish with the clutch learn. But you also said to run through each item, so are you saying to skip those or do them?

You should be ok.

 

[yeahforbes]

After about 2 months since doing the calibrations (but not a ton of driving due to lockdown), I have mixed results. It definitely seemed to help for a while, but now I'm back to getting the occasional false neutral. It's always (or mostly) during a downshift from 3 to 2 now. Since I'm at 32k, I'll just go ahead with the DSG service and keep an eye on things after that.

I know it doesn't mean much thanks to TD1 and other warranty keys/flags, but if I have a dealer do the DSG service and I ask about the false neutral, I guess I'll unmarry the AP just in case that somehow helps avoiding having a warranty claim denied? I might do the DSG service myself though.

 

[jimlloyd40]

After about 2 months since doing the calibrations (but not a ton of driving due to lockdown), I have mixed results. It definitely seemed to help for a while, but now I'm back to getting the occasional false neutral. It's always (or mostly) during a downshift from 3 to 2 now. Since I'm at 32k, I'll just go ahead with the DSG service and keep an eye on things after that.

I know it doesn't mean much thanks to TD1 and other warranty keys/flags, but if I have a dealer do the DSG service and I ask about the false neutral, I guess I'll unmarry the AP just in case that somehow helps avoiding having a warranty claim denied? I might do the DSG service myself though.

Unmarrying the AP won't do any good. The flash counter in the ECU has already recorded how many times you've flashed the ECU.

 

[yeahforbes]

Yeah I know. But it seems like people still do it anyway (even people who understand this). Maybe it's more just as a courtesy to the technician so they can more easily recognize abnormal shifts and loss of power. And also in case they have a heavy foot before proper warmup. Thoughts?

 

[jimlloyd40]

It's up to you to unmarry it. If you feel better than do it. But if you're worried about them having a heavy foot it won't matter whether it's tuned or not the potential damage would be the same.

 

[yeahforbes]

Did the DSG service at a dealership around 33k. No difference... still getting a false neutral every now and then. Only during zero-throttle downshifts (engine braking) to third or second. When it happens, it finally bites after 2-4 seconds.

 

[jimlloyd40]

Did the DSG service at a dealership around 33k. No difference... still getting a false neutral every now and then. Only during zero-throttle downshifts (engine braking) to third or second. When it happens, it finally bites after 2-4 seconds.

You should have the dealer drive it.

 

[yeahforbes]

It only happens every few hours of driving though, so there's an extremely high chance that would end with them finding nothing in exchange for the diagnostic fee.

 

[yeahforbes]

I'm happy to report that despite my Sept 30 messages above, the slipping is definitely less frequent after the DSG service than prior. It's still not completely gone, but it's pretty rare now. Also, while it was previously in several gears, it's now exclusively when shifting from 3 to 2 (which was always the most frequent, but now it's the sole issue).

One thing to note at this point is that I blindly trust that the dealership performed some or all of the adaptations/calibrations during the service -- there's no way for me to confirm of course. I will perform them via the AP at this time, and if there are any effects I'll post here after a few weeks.

Currently at about 36k mi.

 

[billbadass]

might be worth double checking to make sure they filled the DSG all the way up also, have heard of guys overfilling just slightly too

 

[yeahforbes]

might be worth double checking to make sure they filled the DSG all the way up also, have heard of guys overfilling just slightly too

Would that involve draining or is there some kind of dipstick or sensor I can read with VCDS?