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DSG jumping out of gear on take off

goodvibes

Go Kart Champion
Location
IL
I wonder if there's a sensor and where. Extremely unlikely but imagine if adding brake fluid helped, LOL.
 
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victorofhavoc

Autocross Newbie
Location
Kansas City
A bit more on this as I try to get to the bottom of it....

I really think this has to do with the pedal/brake connection that tells the DSG when to engage the clutch. Here me out...

There seems to be a variation in how much brake pedal you need to release/move to get the clutch to engage. This varies from when I start it up/drop the parking brake/put in R or D to being full release and it sits there for a second before going to barely releasing pressure from the pedal and seeing the RPM kick up as it starts to engage. When it's the latter is when I get this issue and this makes sense - it's trying to engage the clutch when it thinks the brake is still engaged so it pops back out momentarily. I feel like the ultra-sensitive brake pedal is more often in sport than drive and I feel like I get this issue more in sport. Make sense?
There's no sport mode for the brake itself. The booster just plays with variations of input amount and time. I'm definitely seeing it less with warmer weather, but it has been 2 weeks since I last drove it. My wife has been driving it and hasn't had a single complaint about the drive. Her driving habits are radically different from mine though.

I almost always restart the car when it's warm but not up to operating temp since I only drivea brisk 10 mins, go into daycare, then come out and leave. My wife will drive 15 or 20 mins in traffic and then park the car until the afternoon or at least a few hrs later.

I am very, very confident this has something to do with a partially warm transmission. Whether it's a temp sensor, position sensor, low fluid, bad fluid, or something else I'm not quite sure yet.

@tigeo ,what fluid are you running now?
 

tigeo

Autocross Champion
There's no sport mode for the brake itself. The booster just plays with variations of input amount and time. I'm definitely seeing it less with warmer weather, but it has been 2 weeks since I last drove it. My wife has been driving it and hasn't had a single complaint about the drive. Her driving habits are radically different from mine though.

I almost always restart the car when it's warm but not up to operating temp since I only drivea brisk 10 mins, go into daycare, then come out and leave. My wife will drive 15 or 20 mins in traffic and then park the car until the afternoon or at least a few hrs later.

I am very, very confident this has something to do with a partially warm transmission. Whether it's a temp sensor, position sensor, low fluid, bad fluid, or something else I'm not quite sure yet.

@tigeo ,what fluid are you running now?
Liquimoly but it did it on the OE fluid as well. I only get this issue when I let off the brake too fast. I can 100% control it by easing that first tiny bit of brake pedal travel off to let it catch then off...it takes a split second that way but never jumps.
 

victorofhavoc

Autocross Newbie
Location
Kansas City
Liquimoly but it did it on the OE fluid as well. I only get this issue when I let off the brake too fast. I can 100% control it by easing that first tiny bit of brake pedal travel off to let it catch then off...it takes a split second that way but never jumps.
Yeah, I'm all identical to this, down to the fluid.

I wonder if we're maybe going about it wrong? What if it's related to the temp of the brake system somewhere? I do have some melted sensors...
 

tigeo

Autocross Champion
Yeah, I'm all identical to this, down to the fluid.

I wonder if we're maybe going about it wrong? What if it's related to the temp of the brake system somewhere? I do have some melted sensors...
I definately get varied pedal-off travel before engagement - sometimes it's instant sometimes I can let the brake pedal out a bit more. The first is when I get the issue. I think it's related to that part of this and nothing to do with the tranny.
 

victorofhavoc

Autocross Newbie
Location
Kansas City
I definately get varied pedal-off travel before engagement - sometimes it's instant sometimes I can let the brake pedal out a bit more. The first is when I get the issue. I think it's related to that part of this and nothing to do with the tranny.
I'm inclined to agree. How are your wheel speed sensors? Mine are melt city from getting the brakes hot on track, but I don't have any faults that would seem related. I know the throttle has a variable position sensor and an override. I'm pretty confident the brake also has a position sensor, but I'm not sure if it's variable and I'm pretty confident it has no override.
 

tigeo

Autocross Champion
I'm inclined to agree. How are your wheel speed sensors? Mine are melt city from getting the brakes hot on track, but I don't have any faults that would seem related. I know the throttle has a variable position sensor and an override. I'm pretty confident the brake also has a position sensor, but I'm not sure if it's variable and I'm pretty confident it has no override.
Some interesting info:

DSG Lag caused by brake switch? | TDIClub Forums
 

victorofhavoc

Autocross Newbie
Location
Kansas City
Interesting, just read the whole thing. So, for a while now I've been considering loosening the dogbone and my other mounts, starting the car, lowering on ramps, and then retightening all the mounts to spec. Technically the engine and transmission wiggle into place as you tighten them one by one, preventing any uneven torque load.

I've just been too lazy and busy to do it. My issue didn't start occurring until after I replaced my dogbone with a full mount from hpa. It wasn't immediate, but months later. Granted, the engagement with the 034 insert was so rough that it felt the entire car was shaking itself loose, so if it did happen I probably missed it a lot.
 

geokilla

Go Kart Newbie
Location
Toronto, Ontario, Canada
Car(s)
2018 VW GTI DSG
Got my stage 1 and DSG tune and it seems to have exacerbated the issue. Still no idea why it's doing this when pulling away from a complete stop but I can say with 100% certainty it happens more when starting on a uphill. My VW mechanic friend is saying it's due to the brake hold interfering with the DSG so maybe I should disable brake hold? It definitely doesn't do it as much on a flat surface or when going downhill.
 

tigeo

Autocross Champion
Got my stage 1 and DSG tune and it seems to have exacerbated the issue. Still no idea why it's doing this when pulling away from a complete stop but I can say with 100% certainty it happens more when starting on a uphill. My VW mechanic friend is saying it's due to the brake hold interfering with the DSG so maybe I should disable brake hold? It definitely doesn't do it as much on a flat surface or when going downhill.
This is likely a different issue that we are talking about here/not related.
 

victorofhavoc

Autocross Newbie
Location
Kansas City
This is likely a different issue that we are talking about here/not related.
Yeah agreed. Either it's different or disabling brake hold will make things worse. What we're talking about feels like the clutch engages, bogs, then disengages, rpm rises, and then it engages again. It's fast, though, maybe half a second. It's so harsh that it's certainly felt like a stumble.

@tigeo, I've been doing some testing and having my wife daily drive the car. It is 100% occurring after a short drive and restart of the engine. If the engine is left on after a cold start, it will not occur! It definitely occurs more (and harsher) if the car was in sport before shutting off.

The question on my mind is, what's different about a warm start for the brake/engine/transmission in terms of what can be signaled electronically and relates to the clutch release of the dsg.
 

geokilla

Go Kart Newbie
Location
Toronto, Ontario, Canada
Car(s)
2018 VW GTI DSG
This is likely a different issue that we are talking about here/not related.

Yeah agreed. Either it's different or disabling brake hold will make things worse. What we're talking about feels like the clutch engages, bogs, then disengages, rpm rises, and then it engages again. It's fast, though, maybe half a second. It's so harsh that it's certainly felt like a stumble.

@tigeo, I've been doing some testing and having my wife daily drive the car. It is 100% occurring after a short drive and restart of the engine. If the engine is left on after a cold start, it will not occur! It definitely occurs more (and harsher) if the car was in sport before shutting off.

The question on my mind is, what's different about a warm start for the brake/engine/transmission in terms of what can be signaled electronically and relates to the clutch release of the dsg.
It's the same issue. If you check my post history in this thread, you'll see I had the same issues prior to the tunes. I got exactly the same thing that you guys are describing. Yet no dealer was able to replicate the issue and that the operation is normal. If it was normal, it wouldn't have happened in my first year of ownership... I mean I could have waited to flash but it is what it is. If my DSG breaks, at least I have service records indicating I reported this multiple times. I didn't wanna hold back on getting it tuned anymore. I paid for it 2 months ago and I wanna start enjoying my car.
 

victorofhavoc

Autocross Newbie
Location
Kansas City
It's the same issue. If you check my post history in this thread, you'll see I had the same issues prior to the tunes. I got exactly the same thing that you guys are describing. Yet no dealer was able to replicate the issue and that the operation is normal. If it was normal, it wouldn't have happened in my first year of ownership... I mean I could have waited to flash but it is what it is. If my DSG breaks, at least I have service records indicating I reported this multiple times. I didn't wanna hold back on getting it tuned anymore. I paid for it 2 months ago and I wanna start enjoying my car.
Are you able to reproduce it by following this process?:
Start cold car and drive for 10 mins
Put it in sport and drive hard for a minute
Park and turn off car
Wait 5 minutes
Start car and check for the bogging behavior

If it does occur, can you prevent or make it better by going back to normal and then to sport again?
 

geokilla

Go Kart Newbie
Location
Toronto, Ontario, Canada
Car(s)
2018 VW GTI DSG
Are you able to reproduce it by following this process?:
Start cold car and drive for 10 mins
Put it in sport and drive hard for a minute
Park and turn off car
Wait 5 minutes
Start car and check for the bogging behavior

If it does occur, can you prevent or make it better by going back to normal and then to sport again?
No the easiest way to reproduce is to pull away from a hill. Whether you're in D or Sport or Eco has no effect on the behaviour. It's most likely a bad mechatronics unit but unless it completely craps out, it's too intermittent to diagnose. My VW mechanic friend said it's highly likely it's the mechatronics too if brake hold isn't interfering with the DSG behaviour. Which in theory makes sense since I never had these issues in my first year of ownership and only now is it getting worse.
 

victorofhavoc

Autocross Newbie
Location
Kansas City
No the easiest way to reproduce is to pull away from a hill. Whether you're in D or Sport or Eco has no effect on the behaviour. It's most likely a bad mechatronics unit but unless it completely craps out, it's too intermittent to diagnose. My VW mechanic friend said it's highly likely it's the mechatronics too if brake hold isn't interfering with the DSG behaviour. Which in theory makes sense since I never had these issues in my first year of ownership and only now is it getting worse.
If it was related to hill assist you'd notice it every single time on a hill of 3% or greater incline (unless you messed with this setting in the registry).

If it's related to the mechatronics unit you'd most likely see other issues in regular shifts beyond just from a start. Not that it couldn't be the actual brains, but it's highly unlikely. More of a failure on the mk6 and even there it was extremely limited in total scope.
 
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