DSG: Problems, Questions, Likes and Dislikes

[Syd118TSI]

...and driving the DSG Golf poops all over driving the Mazda, that's before you even talk about interiors and monkey grins.

[Ryan_R]

I know. It was a minor 'DSG complaint' compared to a conventional auto

[cameronp]

I am just wondering where to start with this one. Which parameters to look at? We know the issue is unwanted delay between when we want to the car to go and when it actually does. But how do we express this in terms of something measurable?

So do I measure..
FROM accelerator press, or
FROM Brake Pedal release

TO RPM rise, or
TO Motion in KMH (from ABS), or
TO Clutch movement...

Had a quick look earlier, thinking I would look to measuring delay from accelerator press to clutch movement. Compare it between Stock and APR tune to see why the latter seemingly does not have the lag. Straight away found this to be flawed way to measure it.
The K1 Clutch moves towards engaging before I even touch the accelerator. It is triggered by releasing the brake pedal. Without actually recording it, I can see the clutch has moved most of the way towards engaged before my foot is fully off the brake pedal it is that quick. This results in the forward creep you will see when crawling in traffic. So no accel pedal at all required. OTOH if you stop on an upslope, release the brake, couple seconds of hill hold, then ABS releases brakes and you merrily roll backward til the cows come home without any hint of clutch movement. I expected it might slowly engage but it does not unless you touch the accelerator in this state. So there is more to the lag than just the clutch.
Also at this point I am looking to find where I can pull the "hill hold active" state out of VCDS. Have not found that one just yet as it would be interesting to see when it triggers. Not that I believe it is the cause of the delay on launch we are looking at.

I've definitely seen the Golf crawl up a fairly steep slope, revving somewhat above idle the in the process. Other times it doesn't. No idea what's going on there.

It would be neat to see a plot of velocity vs time with markers showing the moment that the brakes are released and the moment that the accelerator is pressed. I'm not sure how hard that would be, but from what you said above it sounds like you have a way to get the raw data needed to do that.

[logger]

I've definitely seen the Golf crawl up a fairly steep slope, revving somewhat above idle the in the process. Other times it doesn't. No idea what's going on there.

Yeah it will crawl up a slope just fine, but you will need accelerator to make it launch off the hill hold brake setting. Otherwise it will roll backwards.

It would be neat to see a plot of velocity vs time with markers showing the moment that the brakes are released and the moment that the accelerator is pressed. I'm not sure how hard that would be, but from what you said above it sounds like you have a way to get the raw data needed to do that.

Had a look at doing that this afternoon. My VCDS kit can only grab 9 individual items per second. So in practice this means if I wanted to grab Brakes + Accelerator + Speed (3 items) it would only be looking at each item once every 0.3 of a second. So I could easily end up with an error just under 0.3 of a sec. So instead I tried just grabbing Accelerator and Speed. This allows me to grab each item every 0.2 of a sec. So far if I am reading the data right - it takes just under 0.6 sec from pressing the accelerator until the car moves.
I tested it maybe 30 times, measuring the time from Accelerator press to motion (with & without the ECU tune active). Never got the scary pregnant pause, which from memory is more like a 2 or 3 seconds. The chances of having VCDS hooked up and logging the correct parameters when a bad delay happens seems pretty remote to me. I think my car is behaving properly and the delay between pedal press and movement is perfectly acceptable. This leads me to believe something else is the cause of the pregnant pause when it occurs. As far as I can tell it is not a repeatable state for the car to be in. It is transient. So perhaps either;
1) Some condition that causes the Gearbox to change strategy at the moment of launch, causing the delay, or
2) Adaptation out of whack, causing a one off slow launch, that subsequently cannot be repeated, because the system continually adapts.

Also did some logs with 5 parameters, Brakes + Accelerator + Speed + Clutch1 + Clutch2 but the sample rate meant each item every half a second, so not a lot of use.

[cameronp]

So far if I am reading the data right - it takes just under 0.6 sec from pressing the accelerator until the car moves.
I tested it maybe 30 times, measuring the time from Accelerator press to motion (with & without the ECU tune active). Never got the scary pregnant pause, which from memory is more like a 2 or 3 seconds.

Wow, 0.6 seconds is actually longer than I'd expected - no wonder it's easy to feel the lag on take-off. Pity that the VCDS sample rate is so low. BTW was this with or without the APR upgrade active? If I recall correctly you said that one effect that it had was to make the DSG feel a lot more responsive off the line. I wonder if that's also something that can be quantified.

I ordered a VCDS dongle of my own yesterday, encouraged by the data you've been able to show in threads like this one. With any luck it should get here on Friday so I can play with it on the weekend...

[Corey_R]

Did you get the basic VCDS dongle which only works with Golfs? Or the proper one which is only $100 more but works with every single VW/Audi model there is?

[Ryan_R]

I had a weird one on the way to work this morning. I was slowing up towards a roundabout going up a steepish hill. The traffic cleared while I was still moving (about 15kph in 2nd gear) so I gave the accelerator a bit of a push and heard a clunk. Maybe the car was planning to shift to 1st gear at the precise moment when it suddenly needed 3rd instead. I was turning right at the roundabout, so I was only after just enough power to get up the hill for another 5 or so meters.

[logger]

Wow, 0.6 seconds is actually longer than I'd expected - no wonder it's easy to feel the lag on take-off. Pity that the VCDS sample rate is so low.

Yeah although in perspective, I have logs of it taking 0.33 sec as well. But because of the sample rate I chose to use the event when it sampled the accelerator at ~ 4% or a poofteenth after I pressed it and sensed the speed at 1kph. There are other samples when the pedal is at say 20 or 30% which would have occured several poofteenths after pedal press and therby artificially reducing the time period.

BTW was this with or without the APR upgrade active? If I recall correctly you said that one effect that it had was to make the DSG feel a lot more responsive off the line. I wonder if that's also something that can be quantified.

BOTH - with and without tune -no discernible difference in what I have measured. Having said that I do not believe I am seeing or measuring the delay that scares people. I think this is something different and (I have a hunch) the additional torque available via the tune ameliorates this issue. Will keep looking. Will also do some timing from brake release to movement by holding accelerator against brake, to see if that is any quicker.

[flappa]

Had the DSG "delay" yesterday morning , boy did I have the delay.

Typically , my car is under a carport , and whilst outsides temps are cold , its never directly in the open. I usually have it idling for about 2mins getting my stuff together before I drive off. Dont ever recall having that delay before.

yesterday morning, the car was in the open and had ice all over it. Usual start up procedure ,but when I got to the intersection , it delayed badly. Definently a second or 2 delay before it took off.

In my experience , its only at startup and only when its cold. When its up to basic operating temps , I dont seem to have a problem.

[logger]

In my experience , its only at startup and only when its cold. When its up to basic operating temps , I dont seem to have a problem.

I suspect Cold temps effects some DSGs more than others.
Your DSG6 has a common oil circuit for the entire gearbox. So the same relatively large quantity of combined lubricating and hydraulic oil (~7 ltr) is pumped at an operating pressure of ~ 300psi. Whereas my DSG7 has two independent circuits. One of which is dedicated to the mechatronic unit. It contains only a fraction of the oil quantity (~1 ltr), is optimised for hydraulic use and is pressurised to ~1000psi or 3 times the pressure. Furthermore the DSG6 has a mechanical Oil pump that runs continuously with the engine, whereas the DSG7 has electric system with an accumulator and can operate momentarily including when the engine is off.
So while is makes sense that the cold conditions are effecting your DSG6, chances are a DSG7 may not be effected in the same way.