DSG7 DQ200 0AM - Thoughts about problems

[Geremia]

Hello,
i hope to not disturb with something i would like to share


Perceptible symptoms:

1) Quick sequence of metallic sound knocks (rattle sound) coming from the gearbox, mainly shifting between the first 4 gears (D or M), when at low rpm and few torque request, or anyway on cobbled roads without shifting. Often the engine does not rev up during this rattling.
2) Single metallic knock sound during upshift in M at middle/full throttle, or downshifting with throttle released.
3) With throttle released, downshifting and immediately pressing throttle results in a DSG indecision, lower gear is selected, its clutch is closed, rpm are already stabilized to the lower gear, but engine does not reply to throttle until a timeout occurs after 1-2 seconds which unlocks the indecision (only with the new software).

In November 2011 VW group delivers a TPI for all the brands (Audi, VW, Seat, Skoda), TPI 2027553 for Audi, maybe this number changes from brand to brand but its content does not change, it’s the famous software upgrade:
Customer statement / workshop findings:
Rattling noises from front of vehicle/gearbox on uneven or cobbled roads.
Technical background:
When driving on poor (or cobbled) roads the idling gears of the pre-selected gear start to vibrate and to rattle.
Measure:
The software recognizes the poor road and deselects the gear. The gears are changed faster. This minimizes the rattle after 1-3 seconds. => standard condition!

Problems persist, furthermore the new sw introduces new indecision occasions, so in March 2012 a new TPI 2028692 is delivered:

This claim is simply a comfort problem. Noise is inherent in the design and match the standard technology of the moment.
No components are damaged. Inform the client of this situation

Gears are wet in oil, they should eventually produce a low/thud noise, what kind of tolerance should they have to produce such knocks? DQ250 gearbox, with wet clutches, does not produce that rattle noise.
Why a rattle sound, or better a repetition of a single knock? Looks mostly like a TCU (transmission control unit) indecision.

Googling around we could find lots of nonsense and also some handy material.
Searching “SSP390” we could have the vw selfstudy which roughly describes the gearbox.
Clutches and dual mass flywheel (DMF) are made by Luk, googling “luk_tech_dsg_de_en” we can have their own workshop manual provided within their clutch replacement kit.


Using VCDS, a microphone near the gearbox and a screen grabber something interesting pops up.
This is about an Audi A1 TFSI S-tronic my2012, but any other vw group car equipped with DQ200 7speed dry clutch would suffer pretty the same problem, mostly if drived constantly in city.

http://www.youtube.com/watch?v=ePUgaNH3Y2I

It’s about an upshift 1->2 with rattle sound, both gears are selected and noise comes out when both clutches are slightly pressed (kisspoint is around 7mm). The road is not cobbled at all, it’s perfectly flat.
Monitoring only clutch actuators to have an higher sample rate.

http://www.youtube.com/watch?v=dZpJgJaIKnw

This is the VCDS log:

Marker  TIME    Group 91 - Field 1      TIME    Group 111 - Field 1
        STAMP   Clutch Path 1 -  (G617) Actual position STAMP   Clutch Path 2 -  (G618) Actual position
        40.18.00        6.08    40.37.00        12.05
        40.58.00        6.08    40.78.00        12.08
        40.92.00        2.00    41.11.00        12.01
        41.31.00        2.00    41.52.00        12.00
        41.71.00        2.00    41.87.00        12.01
        42.06.00        2.00    42.26.00        2.07
        42.45.00        7.05    42.61.00        2.07
        42.80.00        11.08   43.01.00        2.07
        43.19.00        11.00   43.38.00        2.08
        43.55.00        10.09   43.72.00        7.07
        43.92.00        10.03   44.07.00        7.07
        44.26.00        9.08    44.45.00        7.07
        44.62.00        9.05    44.80.00        12.00
        44.98.00        7.06    45.14.00        13.07
        45.33.00        2.00    45.53.00        13.03
        45.72.00        2.00    45.91.00        13.03
2       46.08.00        2.00    46.27.00        12.04

43.55.00 10.09 43.72.00 7.07
43.92.00 10.03 44.07.00 7.07
44.26.00 9.08 44.45.00 7.07
44.62.00 9.05 44.80.00 12.00
44.98.00 7.06 45.14.00 13.07

For 1.5 seconds both clutches are beyond the kisspoint while the rattle noise comes out.
Let’s have a look at what happens if going in 1st gear with throttle sobbing on a flat road (quite the same would happen with stable throttle on cobbled road)

http://www.youtube.com/watch?v=qVxHvS2YCEk

No special noise at begin, pretty quiet, one drive shaft has N selected and clutch open, the other drive shaft has 1st gear selected and clutch closed, so I could think no noise from the DMF itself. Once the speed gets higher, the TCU preselects the 2nd gear but leaves its clutch open, the rattle noise comes out.
Which mechanical parts have joined the game? Drive shaft 2 and clutch disc 2 which, even if clutch is open, probably makes small contact on its pressure plate. Where does the noise come out? From the idling gears which vibrates as for the TPI, I continue to not believe at all.

Let’s have a look at the clutch pack, Luk’s pdf turns out handy even if we can’t see details for each single element.



Without putting hands over this iron pieces agglomeration, it’s difficult to spot out the noisy component, maybe parts num 6 and 7, specially those “self-adjusting device” (red dots and yellow circle), in this pic from a russian guy (i don’t remember who and where, sorry) you can see 4 springs being part of the yellow device.



Giving a don’t care to the noise, the question remains: why the single noise is strafed for 1.5 seconds?
Looks mostly like and indecision, but..about what? Gears are already selected, the TCU has only to open one clutch and close the other.
How can the TCU know if the operation has been completed and, as required, smoothly?
It samples 3 sensors:
- G182, returns rpm before clutches, it scans the starter ring gear located on the DMF, rpms are equal the engine ones.
- G632, returns drive shaft 1 rpm (blue)
- G612, returns drive shaft 2 rpm (green)
When value from G182 is equal one of the other 2 located after clutches, it means the clutch stopped slipping, simple and clear. Different timing and pressure strategies are used based on the requested torque (throttle position), while the effective/detected job time, if I’m not wrong, is took in account for further kisspoint adjustment. There are some measuring blocks where the TCU reports something like counters for discarded clutch slippage for this computation, after the rattle sound they are incremented, sadly there is no documentation out here about these counters.


Why the 6 speed DQ250 does not make such rattle noise? Let’s go comparing them


Details of DQ200 DMF




Here the 6 speed DQ250 gearbox, clutch pack, DMF






One thing catches eyes when comparing DQ200 0AM and DQ250 02E (6 speed with wet clutches, without rattle sound):
In DQ250 the pre-clutch speed sensor (G182) scans rpm on the clutch pack (secondary mass), while in DQ200 it scans on the starter ring gear (primary mass), in other words, for DQ250, any DMF oscillation is insignificant because it affects all the 3 speed sensors at the same time (G182, G632, G612), while in DQ200 is significant because it affects only G632/G612 but not G182

If “idling gears start to vibrate and to rattle” is not convincing at all, this speculation makes at least some more sense:

During a shift on the first gears (1 to 4), at low vehicle speed (low aerodynamic drag) with low throttle, both clutches comes slightly pressed on their pressure plate, an alternation of positive/negative torque is created (now one prevails, now the other) which is transmitted to DMF which starts to oscillate. TCU compares G182 (stable) and G632/G612 (oscillating) but it can’t be sure if and how much the clutches are slipping, finally it reaches a timeout and discards the smooth transition approach. Alternation/bounce reflects to the not-firm components of the clutch pack which causes the repetitive rattle noise. The software kisspoint auto-trim function and the mechanic self-adjusting device result to be not reliable, so they fail their purpose and the clutch disc will wear out prematurely.

For sure we can’t evaluate the advanced tech level reached by VW group just using a couple of pdf and some measuring block sampled at 2.5 sps.
For sure VW group betatesters reported weird issues on the first gears (or do they drive hundreds of km only on highways?), the Tricore CPU, which should be the one inside the TCU, can reach 200Khz sampling rate on the A/D converters, for sure it can clearly see the situation, for sure someone at the DSG department triggered a trace log to take a look deeply.
Maybe VW asked Temic to solve the issue by sw, maybe Temic told “first take this beta sw i’ve in the drawer, go putting G182 on the clutch pack”, maybe Luk told “go designing a new crankcase while I put some magnets on the clutch pack”.
Maybe is better to do nothing, just warranty extension to the most boring, like China, Russia, Taiwan.
Maybe 1.5 seconds of stall, rattle sound, excessive slippage are really just a comfort issue, everyone is free to think, evaluate, believe.

About the 3rd symptom, it seems mostly a sw bug, just a doubt to be cleared: does the vehicle still stays approved/certified for public roads driving even if a new gearbox sw update introduces occasional stall of about 1-2 seconds while pressing throttle after downshifting?


Good luck

J3

[Z-Rain]

Okay mister!

[Radio]

Geremia, хоть бы загуглоперевел.

[InterPaul]

Вообще статья ни о чем.
Ну есть стук, и что? Предложено решение проблемы или хотя бы мысли о том что может быть? Нет. Просто куча текста и малопонятных фоток.
А завершение опуса вообще классное "Maybe is better to do nothing" - нафига вообще что то делать? типа стучит и стучит...
Незачот, тему в топку.

[kott]

Geremia, а это что за непонятные буквы и картинки?

[InterPaul]

Это типа английский язык
Но нафига он тут - вот это серьезный вопрос...

Кстати, там по тексту есть ссылка на некоего "russian guy" (блин хорошо хоть не gay), который типа исследовал проблему. Это не уважаемый UKV случаем?

[Vano69]

Geremia, What the fuck???

[Январь]

Интересный спасибо очень 12 утра информация.
Но было бы если взять, то 13 дня будет ли так???

[UKV]

Цитата:

Сообщение от InterPaul

...
Кстати, там по тексту есть ссылка на некоего "russian guy" (блин хорошо хоть не gay), который типа исследовал проблему. Это не уважаемый UKV случаем?

Нет..., это фото старого сцепления AndyAstra.

Цитата

...in this pic from a russian guy (i don’t remember who and where, sorry) you can see 4 springs being part of the yellow device.

Вот ссылка на первоисточник: http://www.drive2.ru/cars/skoda/octa...6863888647144/

добавлено через 16 минут

Цитата

Сообщение от Geremia

Hello,
i hope to not disturb with something i would like to share
...

Geremia, thanks a lot!
Welcome to our forum, I hope it will be interesting for you.
Please do not hesitate here to ask about anything from "VAG world". If we can, we would help.

Geremia, спасибо большое!
Добро пожаловать на наш форум. Надеюсь он будет интересным для тебя!
Не стесняйся спрашивать нас обо всем, что касается "мира VAG". Если мы сможем, мы поможем.

[Никанор]

По ссылке уважаемого UKV,получается, что износ накладок сцепления даже при пробеге за 100000 км минимальный. Хоть это радует.