My experience driving DSG (S tronic)

[friendly_jacek]

I rented Audi Q5 while traveling in Europe. Very good ride despite limited HP (170 or so with the 2.0 Diesel). The transmission was very smooth with hard to notice shifts. I would say better than conventional auto tranny with torque converter.

The only annoyance was when I mashed gas from standing still (like waiting to turn left) while in Drive. There would be almost a second of delay. I almost had an accident once or twice because of that.

Someone told me later to use S on the shifter, but I never remembered to use it.

According to wiki, while in D, the DSG starts in second gear and pressing gas pedal fully will produce a delay to downshift. IMHO, this is not the best idea. Is every DSG like this?

http://en.wikipedia.org/wiki/Direct-Shift_Gearbox

BTW, I personally find the Audi controls for audio, climate and navigation extremely non-intuitive.

 

[dparm]

I think you're misreading that. It definitely starts in first gear...I have an S tronic car.

 

[friendly_jacek]

Originally Posted By: dparm
I think you're misreading that. It definitely starts in first gear...I have an S tronic car.


Maybe, this is the text:

Quote:
"D" mode

Whilst the motor vehicle is stationary and in neutral (N), the driver can select D for "drive" (after first pressing the foot brake pedal). The transmission's reverse gear is selected on the first shaft k1,[3] and the outer clutch K2 engages at the start of the 'bite point'. At the same time, on the alternate gear shaft, the reverse gear clutch K1 is also selected[2][3] (pre-selected), gearbox still doesn't know whether the customer wants to go forward or reverse (could still change even though its in d) but the clutch pack for second gear (k2) get ready to engage . When the driver releases the foot brake pedal, the k2 clutch pack increases the clamping force, allowing the second gear to take up the drive through an increase of the 'bite point', and therefore transferring the torque from the engine through the transmission to the drive shafts and road wheels — and the vehicle moves forward. Pressing the throttle / accelerator pedal fully engages the clutch and causes an increase of forward vehicle speed. Pressing the throttle pedal to the floor (hard acceleration) will cause the gear box to kick down to first gear to provide the acceleration associated with first, although there will be a slight hesitation while the mechatronics deselects second gear and selects first gear


BTW, I drove the 7-speed S-tronic.

 

[dparm]

Just read that a few times. That is not well worded.

Regardless, I drive with it in S mode all the time anyways (usually in manual mode) so I don't really notice this or care.

 

[friendly_jacek]

I just did a quick search and other Audi Q5 owners noticed the same quirk:

http://www.myaudiq5.com/index.php/topic/1117-s-tronic/

Quote:
I have 2 Audi`s.Both 2010.
An A3 2.0 tdi 140 s-line s-tronic.
A Q5 2.0 tdi 170 s-line stronic.
The a3 has no lag and takes off like a rocket no lag no problem.
The Q5 sits there after you accelerate and decides to go at its own leisure sometimes quick and other times with a 2 to 3 second lag. Dam right dangerous at times. I now just wait for a bigger gap in the traffic.
My point is that here we have 2 diesels almost the same displaying totally different auto characteristics. I am convinced it it the gearbox and not the 2 litre diesel engine.

 

[Quattro Pete]

Originally Posted By: friendly_jacek
Is every DSG like this?

If it's truly the case, I would guess it is vehicle/implementation specific since it's just a matter of software.

FYI, the conventional auto trans on our C300 works just like this - starts in 2nd gear when in "D" mode, and it makes the car painfully slow to get going. Hence we keep it in "S".

 

[dparm]

Pete, I'd disagree -- in this case the reason for starting in 2nd is mechanical (due to the design).

Regardless, S tronic is frickin AWESOME to drive. 8ms shifting? Yes please.

 

[Quattro Pete]

I'm not sure I follow you. If it's mechanical, then how come it can start in 1st gear when in "S" mode?

 

[dparm]

Originally Posted By: Quattro Pete
I'm not sure I follow you. If it's mechanical, then how come it can start in 1st gear when in "S" mode?



Because in that case it is not pre-selecting R, unless I'm totally off-base. I have one of the Audi technician study guides on S tronic but have not yet read it.

Isn't it:

R-2-4-6 (shaft one)
1-3-5-7 (shaft two)

 

[SteveSRT8]

The programming is what's different. Vastly different from platform to platform.

Example: New C&D test of BMW vs. Audi, EXACT SAME ZF 8 speed trans. Audi was noticeably better, just better tuning.

 

[dparm]

Is BMW using the Borg-Warner too? The DCT in the M cars is Getrag.

 

[mechtech2]

After doing it wrong 10 times, most people would remember to put it in 'S'.

 

[chrome]

I agree with dparm, the wiki page seems poorly worded, and seems to imply the DSG will start off in 2nd gear unless floored past the kickdown switch.

This is not what I observed in my VW Jetta with the 6-speed DSG. It will always start from a standstill in 1st (observable from the gear indicator on the instrument cluster) and upshifts to 2nd when appropriate. S-mode just pushes the upshift point higher in the rev range.

 

[chiks]

Slow computing power is the cause. It needs a faster processor that can determine all that it needs to in order to reduce/emiminate the lag

 

[SteveSRT8]

Originally Posted By: dparm
Is BMW using the Borg-Warner too? The DCT in the M cars is Getrag.


They use other transmissions, but they are using a TON of the ZF 8 speeds as they are ultra versatile. Hybrids and conventional drivetrains.

 

[Quattro Pete]

Originally Posted By: chiks
Slow computing power is the cause.

How do you know this? Processing power is cheap these days. I really doubt that a car manufacturer would leave a serious issue like this unresolved if it could have been easily addressed by a slightly more expensive CPU.

 

[Hokiefyd]

If you put it in S, does that force you to then sequentially tap the shifts up/down? If so, that's a very poor implementation of an automatic transmission in my opinion.

I had something akin to that in my 2011 Camry. The transmission would shift way too soon and would shift in/out of gears unless I kept it in sequential mode. It would work fine in sequential mode, but one shouldn't have to do that.

 

[SteveSRT8]

They have to program in SOME delay, because some people have a spastic foot! The key is how much.

I am with Pete as the PCM processing speed is unlikely to be the cause of this issue.

 

[KrisZ]

As with most modern automobiles, lousy programming is most likely the cause.
Just an example, an average commercial aircraft has about 3-5 million lines of code and that includes redundant systems. Cars on the other hand can have 50-100 million lines of code.

 

[dparm]

Originally Posted By: Hokiefyd
If you put it in S, does that force you to then sequentially tap the shifts up/down? If so, that's a very poor implementation of an automatic transmission in my opinion.

I had something akin to that in my 2011 Camry. The transmission would shift way too soon and would shift in/out of gears unless I kept it in sequential mode. It would work fine in sequential mode, but one shouldn't have to do that.



No. S is still "full auto" it just holds gears longer, downshifts more liberally, and uses engine braking a bit more.

You tap it to the manual mode for full DIY shifting.