Team-BHP - DSG, demystified! All you need to know about VW's Direct-Shift Gearbox

Quote:

Originally Posted by Gurudeep BN (Post 5922750)

Issue:
There is a lag of about 2-3 seconds for the vehicle to move from P to D/S on engine start.
- This issue has been there for about 3y.
- 3y back, when I first reported this to VW.

Other queries:
1. Since the car is now 9+ years old and DSG failure is number 1 probability wise, is there a way to get the diagnostics run to determine any failure or wear and tear of parts possibly indicating a future failure?
2. Is there a way to determine if gearbox and mechatronics oil change are required?
3. Get checked for any software update?

Dear Gurudeep,

Sorry for delayed response.

Issue that you are facing might be typical of failing mechatronic pressure pump - that generates pressure in mechatronic unit oil - that in turn executes changes in solenoid valves - that implement gear changes. Gear changes are less frequent in highway run & that's good for us. Pressure loss is not immediate but gradual in most of the cases - damaged piston or damaged pump metal wall could be the cause. These pumps work at very high pressure & even a minor invisible crack can be a cause of pressure loss.

You could change the the pressure pump assembly + mechatronic fluid at an experienced FNG - I doubt VW will do that as it's quite technically demanding & is a tedious task. They will probably be more interested in replacing whole unit - for better margins & lesser headache. A good & deep OBD scan can reveal low fluid pressure. What I can understand is that pump unit is taking time to reach working pressures in order for solenoids to get going.

If pump assembly change can't be done, you should be changing mechatronic fluid atleast - new fluid at 9 years mark can work wonders as it's viscosity will be quite lower compared to old fluid - which will certainly help in quicker gear shifts.

After reading your post, I have tried multiple times on my DSG (DQ381) - in my case ignition & P to D vehicle movement takes approximately 1 to 1.5 second. N to D is almost immediately with engine running. I am at 50K KMs.

I doubt any software update will help. Also, I am against DSG reset in your scenario.

Hoping you get it sorted out soon.

Regards,
SilverSmoke.

What I have observed in the 350km with the Virtus 1.5TSI 7DSG, DQ200 is the following:
* Very eager to move to D2 from D1 - can happen as low as 5kmph
* Not eager at all to move to D1 from D2 - sometimes, it happens as low as 4-5kmph.
* If in M-mode, TCU prevents upshift from M1 to M2 before 15kmph
* If in M-mode, TCU forces downshift from M2 to M1 around 10kmph (need to re-check this, but definitely >= 7-8kmph)

Need to observe more, but what I realized is the following:
* For Manual Mode, M, the TCU is enforcing reasonable upshift, downshift between M1 <-> M2 (and other Mx gears as well).
* For Drive Mode, D, the TCU is too eager to upshift, and too reluctant to downshift
* For Sports Mode, S, the upshift case is helped (as S holds gears longer). However, even S doesn't downshift early from S2 to S1.

So, I have been trying to adapt moving to M when slowing at red light, stop-go jams, and/or over mountain Bangalore speedbreakers. Challenge is to remember to upshift when accelerating from M1 (esp when turning and the paddles are not in their rest position), or nudge the DSG lever back to D.

Shifting to N at stops beyond 5-10s.
Thoughts ?

Quote:

Originally Posted by lancer_rit (Post 5963943)

Another ~85km on the weekend, and in M-mode, the TCU forces downshift from M2 to M1 at ~12kmph. Sometimes, depending on how sharp the deceleration is, it may be lower or the speedo may not be updating the instantaneous speed quickly enough...

And in stop-go crawls, I do thinks its better to switch to S mode, will prevent going into S2 unless 15kmph is hit. This reduces the need to downshift manually. If and when paddle downshift is needed, the TCU will switch back to S instead of D, and then again hold S1 longer than D1 would.