APR: C7.5 S6 TCU issues

[kenny_l]

I have two problems:

1) cruising in 4th or 5th (about 30-35mph?); come up to the place I'm about to turn into, start applying brakes, then hit downshift paddle twice (seems to be in 4th when I do this, and I like to take it to 2nd), takes the car a full second to shift. I don't believe it happens if I am not applying brakes first. Dashboard display does correctly report the intended shifts as I press the paddle though.

2) when being somewhat heavy on the gas from a stop - not flooring it, not easing it, but a quick transition to, say 60 or 70% (I don't have VCDS to tell you, assuming it does indeed log throttle position) - car acts like it's about to go, but then if I back off ever so slightly (because I think I'm about to overdo it from a light), transmission gets too proactive and shifts up hard immediately, lots of vibration, car feels like bogging and doesn't go as quick as I want it to. I wasn't paying attention to gearing.. I know if I had VCDS this would be much more helpful...

Anyone else experience similar?

[Sean@APR]

I have two problems:

1) cruising in 4th or 5th (about 30-35mph?); come up to the place I'm about to turn into, start applying brakes, then hit downshift paddle twice (seems to be in 4th when I do this, and I like to take it to 2nd), takes the car a full second to shift. I don't believe it happens if I am not applying brakes first. Dashboard display does correctly report the intended shifts as I press the paddle though.

2) when being somewhat heavy on the gas from a stop - not flooring it, not easing it, but a quick transition to, say 60 or 70% (I don't have VCDS to tell you, assuming it does indeed log throttle position) - car acts like it's about to go, but then if I back off ever so slightly (because I think I'm about to overdo it from a light), transmission gets too proactive and shifts up hard immediately, lots of vibration, car feels like bogging and doesn't go as quick as I want it to. I wasn't paying attention to gearing.. I know if I had VCDS this would be much more helpful...

Anyone else experience similar?

Both are new to me. I'll PM you my email, I'd like to get a ticket open for these. We are currently working on getting a C7.5 in house again to look at a few other DSG quirks.

[kenny_l]

Will do - fyi on the second issue, it seems like this might just be the traction control kicking in. The last time it happened, I think I noticed a yellow flash at the top of the display, but it disappeared as fast as it appeared (or I was seeing things).

[Sean@APR]

Will do - fyi on the second issue, it seems like this might just be the traction control kicking in. The last time it happened, I think I noticed a yellow flash at the top of the display, but it disappeared as fast as it appeared (or I was seeing things).

Ahh, yes.. that will happen.

On the first one, can you possibly make a phone video of it happening? That could simply be that you're asking for too much of a downshift. It won't downshift below an "engine stall" threshold.

[kenny_l]

I might be misunderstanding - when I'm downshifting, the new engagement rpm is higher than where I started though, right? Not sure how this applies. I'll try to take a video next time. RPM is probably around 1000-1200 in 4th before I shift to 2nd.

[Sean@APR]

I might be misunderstanding - when I'm downshifting, the new engagement rpm is higher than where I started though, right? Not sure how this applies. I'll try to take a video next time. RPM is probably around 1000-1200 in 4th before I shift to 2nd.

Forget that whole post, my brain obviously wasn't engaged. The stall threshold is for upshifts.

On downshifts, are you tapping the handle twice in quick succession? If you tap it once does it shift right away?

DSG transmissions have two shafts, odd gears on one and even gears on the other. If you want to go from an even gear to another even gear, it can't go directly. It has to shift to an odd gear first, then re-position the forks on the even shaft before it can shift back to there.

I'm not sure what the display shows while it's doing that. I'll try it on the drive home tonight.

[kenny_l]

Sorry for the delay - I wasn't able to get a video yet, but I did get a speeding ticket :)

I was tapping it twice (and the display updates right away), but the shift delay also happens if I downshift just once. It's taking more than a second at times, although the display always updates instantly. You have to have just started hitting the brakes before shifting - there must be some kind of window although it is pretty consistent for me. I'll get a video soon

[Sean@APR]

Sorry for the delay - I wasn't able to get a video yet, but I did get a speeding ticket :)

I was tapping it twice (and the display updates right away), but the shift delay also happens if I downshift just once. It's taking more than a second at times, although the display always updates instantly. You have to have just started hitting the brakes before shifting - there must be some kind of window although it is pretty consistent for me. I'll get a video soon

Without a video, I can't be 100% sure, but I tried several times on my car and couldn't duplicate this. That leads me to think this is a specific issue to your year. I notified the person in charge of those and he's looking into it.

[kenny_l]

ok, sorry it's blurry.. I actually took several videos in a row - all exhibited the issue - but only one did I manage to actually film the tach. Anyway we start in 5th and about midway I say brake and then say shift. The display goes from D5 to M4 and then eventually you see the tach move. it may look sideways depending on what player you use, not sure why. I'll try to get a better one tomorrow.

https://drive.google.com/file/d/0B4p...ew?usp=sharing

[kenny_l]

another note.. if you play this using google drive's built in browser media player, the audio is late. If you notice when the 5 changes to a 4, that's actually when I said "shift", but you don't hear it until after the visual change if you're playing it through google drive.. so I recommend just using the visual change as the cue for when I pressed the paddle. Or use a different player.

[kenny_l]

so, almost 2.5 seconds to shift on that video... I tried it today from around 55mph and wasn't able to get it to happen (brake and then paddle-shift resulted in an almost immediate gear change)

[Sean@APR]

Thanks for making that, it clarifies the situation very nicely. I've passed the video along to the calibrator and we'll see what he says about it.

[kenny_l]

Hi, I was wondering if the delayed manual shifting issue has had any progress. Thanks

[kenny_l]

I guess not! :P