DSG7 0AM Vag Com Data Logs

[logger]

I have started this new thread about the DSG7 0AM here in MK6 because my contributions to the original thread at MK5 diverged into discussing a MK6 gearbox. I know there are lot of DSG threads already, but this one might focus a bit on answering questions by capturing what the DSG7 is actually doing via VagCom.

To get your mind around how it all works here is a drawing of the innards.


With VCDS, I can log lots of parameters slowly, or 1 or 2 parameters quite quickly. Sample rate ranging from ~ 1 per second to ~ 10 per second. So if you have suggestion on what might be worthwhile looking at let me know.

.. and to get the ball rolling here are the two excel logs I have made to date.
1) 4 minute drive in "D" with the TSI118 DSG7 reversing, stopping and starting several times and going through all 7 forward gears. DSG7 Drive Log.xls
2) Crawling along at idle on a flat road, Starting and stopping 3 times using different Gear Selector positions. 6kphStartStop3Times.xls

I can tell you, trying to understand how this thing works is a great way to fry your brain.

PS. when I labelled the drawing above I was gunna switch all the Gear Numbers to confuse the hell out of everyone but I decided against it

[soogs]

You have opened a can of worms. To start the ball rolling, I've a quetion and a suggestion.

Q1. When you are coasting without any accelerator input, is the clutch disengaged eg in neutral like in a manual? The reason for this question is generally when i coast to a red light, I shift the gears to neutral both in manuals and autos, in the belief that it may save gas, probly a misconception that it does. I guess you should be able to tell as the rev should drop to idle.

S1. Since the DSG is computer controlled, wouldn't it be nice if we can somehow input the gear mapping with a push of a button in say 4 patterns from nanny to hoon. Shouldn't be hard to acheive and probly more useful than ACC, as from the other thread most say D upshifts too early and S is to aggressive.

TIA

[Frankenstrat]

You should NEVER coast in a standard automatic gearbox. You will blow the seals and possibly cause other damage to occur. As for the DSG, I'll leave that to someone more familiar with that particular gearbox.

[cktsi]

So from rows 47-54 were you creeping in "D1" (on MFD)? If so, were you getting the mild bumping?

I can see from your sheet that the clutch plates are being 'feathered' i.e. being modulated only slightly.

My suggestion (and one Blutopless2 might also be interested in) is sampling rate 10 per second and just crawl in D1 - preferably up a reasonable incline - not too steep but enough to trigger the bumping. Don't do it for too long of course.

It's would be interesting to see the variation in K1 expanding & contracting.

btw... you must be a real car nut cos you even spent a few hrs with the car jacked up, spinning the wheels, reading Vagcom & looking at the gears??

Nice diagram... I say that cos I cannot find 0AM on the internet (but I have 02E) and it's exactly as you described it in the other thread & as I consequently envisioned it.

The surprise is the reverse gear as it differs to 02E diagram. Maybe the depiction is confusing, but in 02E it depicts
1. torque coming off the drive shaft,
2. onto the reverse gear shaft, then
3. back onto the output shaft with the forward high gears 5 & 6, then
4. the differential.

Whereas this diagram is showing (and I could be reading it wrong & it isn't the flow diagram anyway - but merely highlighting the connecting cogs)

1. torque coming off the drive shaft, then
2. the output shaft with the forward high gears 5, 6, 7 then (compared to R shaft in 02E)
3. onto the reverse gear shaft, then
4. the differential.

Hopefully i've got it wrong and there is a transmission power flow diagram depicting reverse? Sorry to ask, but I know it's a real question.

[logger]

You have opened a can of worms. To start the ball rolling, I've a quetion and a suggestion.

Q1. When you are coasting without any accelerator input, is the clutch disengaged eg in neutral like in a manual? The reason for this question is generally when i coast to a red light, I shift the gears to neutral both in manuals and autos, in the belief that it may save gas, probly a misconception that it does. I guess you should be able to tell as the rev should drop to idle.

Here you go 50kphCoastDvsN.xls Shows you what the clutches do two similar accels up to 50kph then a coast back down to a stop. The first event is doing the decel in "D" Drive and the second in angels Gear "N". As you will see, both clutches open in "N" (as you would expect). However in "D" they alternate one clutch being engaged to some extent all the time with a degree of slip occuring. This XLS logs clutch torque, commanded and actual positions. There is a 2nd sheet in there with another longer decel in "D"

S1. Since the DSG is computer controlled, wouldn't it be nice if we can somehow input the gear mapping with a push of a button in say 4 patterns from nanny to hoon. Shouldn't be hard to acheive and probly more useful than ACC, as from the other thread most say D upshifts too early and S is to aggressive.

Yeah that would be neat. On the other hand, I s'pose "D" could be considered the Nanny mode, "S" for hoons and Tiptronic for home brew. BTW, Took me a while to work out the only thing the cable from the Gear selector to the gearbox does is to set the park brake Rest is controlled by the PFM box.

[logger]

So from rows 47-54 were you creeping in "D1" (on MFD)? If so, were you getting the mild bumping?

No 47-54 on the "0-6km 3 times" sheet was in Tiptronic mode, gear "1" and no bumping whatsoever.

I can see from your sheet that the clutch plates are being 'feathered' i.e. being modulated only slightly.

yes hence the slipping

My suggestion (and one Blutopless2 might also be interested in) is sampling rate 10 per second and just crawl in D1 - preferably up a reasonable incline - not too steep but enough to trigger the bumping. Don't do it for too long of course.

It's would be interesting to see the variation in K1 expanding & contracting.

Will place that on the job list

btw... you must be a real car nut cos you even spent a few hrs with the car jacked up, spinning the wheels, reading Vagcom & looking at the gears??

.. and there is still plenty in there that is puzzling so there will be more jacking and spinning required

Nice diagram... I say that cos I cannot find 0AM on the internet (but I have 02E) and it's exactly as you described it in the other thread & as I consequently envisioned it.

The surprise is the reverse gear as it differs to 02E diagram. Maybe the depiction is confusing, but in 02E it depicts
1. torque coming off the drive shaft,
2. onto the reverse gear shaft, then
3. back onto the output shaft with the forward high gears 5 & 6, then
4. the differential.

Whereas this diagram is showing (and I could be reading it wrong & it isn't the flow diagram anyway - but merely highlighting the connecting cogs)

1. torque coming off the drive shaft, then
2. the output shaft with the forward high gears 5, 6, 7 then (compared to R shaft in 02E)
3. onto the reverse gear shaft, then
4. the differential.

Hopefully i've got it wrong and there is a transmission power flow diagram depicting reverse? Sorry to ask, but I know it's a real question.

You haven't got it wrong, thats how it works. Not that I have studied the 02E DSG6, but it sounds to me like it only has 2 output shafts. Whereas this little marvel has 3. Gear wheel R1 will always idle on shaft 2 (otherwise there would be a serious problem) & R gear is actually selected on R2 on shaft 3.

[logger]

Would this make sense for set of gear ratios including the final drive?

1st 17.36
2nd 10.19
3rd 6.7
4th 4.91
5th 3.90
6th 3.01
7th 2.66

[Stoney!]

Q1. When you are coasting without any accelerator input, is the clutch disengaged eg in neutral like in a manual? The reason for this question is generally when i coast to a red light, I shift the gears to neutral both in manuals and autos, in the belief that it may save gas, probly a misconception that it does. I guess you should be able to tell as the rev should drop to idle.

TIA

There is no need for this as when you lift your foot off the throttle in the vee dubs it completely shuts the fuel of (i.e. 0.0L/100k's) and whilst in gear it uses the momentum of the car to keep the engine turning, in neutral it requires fuel to idle so you will actually use more by doing this! (i.e. 0.7L/hour, L/100k's depends on current speed)

and in cars that don't have this feature, whatever you save in fuel will probable be burnt by brake and transmission life....

Stoney!

[logger]

There is no need for this as when you lift your foot off the throttle in the vee dubs it completely shuts the fuel of (i.e. 0.0L/100k's) and whilst in gear it uses the momentum of the car to keep the engine turning, in neutral it requires fuel to idle so you will actually use more by doing this! (i.e. 0.7L/hour, L/100k's depends on current speed)..

Good point Stoney. That would explain why in the decel from 50 to 0 in Drive it still works its way down through the gears swapping clutches along the way. Initially I thought, why so busy, doing all that changing during a coast. It now makes sense that it would do this to keep the engine speed windmilling near some target of around 1,000 rpm.

[soogs]

There is no need for this as when you lift your foot off the throttle in the vee dubs it completely shuts the fuel of (i.e. 0.0L/100k's) and whilst in gear it uses the momentum of the car to keep the engine turning, in neutral it requires fuel to idle so you will actually use more by doing this! (i.e. 0.7L/hour, L/100k's depends on current speed)

and in cars that don't have this feature, whatever you save in fuel will probable be burnt by brake and transmission life....

Stoney!

Would a DSG coast further from 50 to 0 in neutral than in D? If it does then fuel savings would negate each other, as you have pointed out it uses fuel in neutral but then it may coast further unless the friction losses in gear is minimal.