Auto hold - DSG - burning clutch?

[Hillbilly]

To my knowledge, when stationary, with the selector in any position other than P or N, on the brakes or with the handbrake engaged, the gearbox has first gear (or reverse gear) selected, and the clutches are disengaged. The clutches engage when you use the accelerator, or motion is detected.

You can test this for yourself. Disable stop/start and autohold, stop on an incline. When you release the brakes, you'll feel the car roll backwards for a fraction of a second before the clutches engage and slow or stop the rollback. The effect can be disconcerting if you're not expecting it, especially when reversing, but you can mitigate the effect with auto-hold.

The hill start assist governs the starting torque when pulling away on an uphill incline and interacts with the hydraulic brake assist and the transmission control to prevent the vehicle from rolling backwards by applying the brakes. This makes controlling the vehicle during hill starts simple and convenient for the driver. So there is no need to worry about the vehicle rolling backwards or the engine stalling.

From the technical page of VW

[wai]

Hoping someone is in the know...

Here's the scenario. Start stop is on and auto hold is on. Sitting at the lights, after taking your foot off the brake, the engine starts again but auto hold prevents the car from moving forward. In this scenario, I understand the brake is held but is the clutch burning ready to take off or is it sitting in nutral? Currently I avoid having the car stationary with the auto hold function on fearful of burning the clutch.

No, the clutch will not start engaging until the system detects a change in accelerator position. At that point the brake will disengage and the clutch engage.

With a DSG, you do NOT want to try and hold the vehicle n the hand brake only as now the clutch will try and engage. You have to have your foot on the brake where a sensor will disengage the clutch.

[Creniac]

Here's a scenario I experienced many a time in my Jetta.... I have a steep driveway, I would often pull up the driveway, use the autohold feature to hold me in position while my son reached into the letterbox to collect mail.... it was about now I realised a huge issue with auto hold... I'm not sure what sensors come into play but as I tried to accelerate away the autohold feature would not let go although I was throttling on... yes I had the 7DSG but the autohold refused to let go many a time... After experiencing the autohold locking me down a few times I got the sh*ts to say the least.... each time engine revs increased and the horrid smell of clutch burn entered the car..... I eventually had to avoid this and walk back down the driveway to collect the mail in fear of burning the clutch pack out!
I have since got rid of this car due to many issues experienced with it... not only this issue but the fact the DSG mechatronics issue got me as well..... good news is I still love VW now that I have a manual Tiguan....

[Hillbilly]

Here's a scenario I experienced many a time in my Jetta.... I have a steep driveway, I would often pull up the driveway, use the autohold feature to hold me in position while my son reached into the letterbox to collect mail.... it was about now I realised a huge issue with auto hold... I'm not sure what sensors come into play but as I tried to accelerate away the autohold feature would not let go although I was throttling on... yes I had the 7DSG but the autohold refused to let go many a time... After experiencing the autohold locking me down a few times I got the sh*ts to say the least.... each time engine revs increased and the horrid smell of clutch burn entered the car..... I eventually had to avoid this and walk back down the driveway to collect the mail in fear of burning the clutch pack out!
I have since got rid of this car due to many issues experienced with it... not only this issue but the fact the DSG mechatronics issue got me as well..... good news is I still love VW now that I have a manual Tiguan....

Auto hold and Hill start assist are two different things Auto hold can be turned on and off Hill start is built in and works automatically.

Auto hold works as part of the Electric handbrake and Hill assist works with the Hydraulic braking

Have a read of this page Auto Hold Function < Technical Glossary < Innovation & Technology < Volkswagen International

If you are only stopping for half a minute I would have just kept my foot firmly on the footbrake.

[wai]

I have the exact opposite with my Caddy.

I stop on a hill facing uphill and try ad drive up. I press the brake pedal to engage hill hold and the pedal comes up hard. I take my foot off the brake and press the accelerator. The brake releases immediately and the clutch engages around 1/4 second later. The result is I roll back a little. Not too bad.

I stop on a hill facing downhill and try and reverse up. I press the brake pedal to engage hill hold and the pedal comes up hard. I take my foot off the brake and press the accelerator. The brake releases immediately and the clutch takes around 1 second to engage. I start rolling forward, so my reaction is to press the accelerator a bit more. The clutch engages and I am launched backwards. I jump on the brake and the loop starts again.

The only way around this is to use the handbrake (conventional type) and use it the same way you would with a manual transmission.

Now there are two types of hill assist. One is called hill hold, and the other called hill start.

The hill start version is supposed to release the brake gradually rather than instant off. It will also hold the car with your foot off the brake for up to 3 minutes. The clutch is not engaged until accelerator position changes.

The hill hold version releases the brake instantly. It will also hold the car with your foot off the brake but for just 3 seconds. The clutch is not engaged until 1 second after accelerator position changes.

The sensor that is used to work out when to release the brake is the one that detects accelerator position.

[Creniac]

HillBilly, sorry put ya crook last night.... yes it was the Hill Start feature on my Jetta 7DSG that was at fault not the auto hold (Auto hold on is my Tiguan)...... yes different but hill start was the issue on a steep incline.

[kleung]

The hill start assist governs the starting torque when pulling away on an uphill incline and interacts with the hydraulic brake assist and the transmission control to prevent the vehicle from rolling backwards by applying the brakes. This makes controlling the vehicle during hill starts simple and convenient for the driver. So there is no need to worry about the vehicle rolling backwards or the engine stalling.

From the technical page of VW

...except Hill Start is not fitted to the Passat. It is, however, fitted to Golfs.

From the VW Australia 2012.5 Golf brochure:

Hill Start Assist (HSA) (not pictured)
Hill Start Assist holds the vehicle stationary for 1.5 seconds on hills with an incline greater than 5 percent, when the foot brake is released, by temporarily locking the brake pressure. This intelligent feature provides a comfortable hill start, which importantly avoids any rolling back.

I can definitely tell the difference when I'm driving my father's Golf vs my Passat. Auto-Hold annoys me (so I leave it turned off 99% of the time), but the HSA function makes it much easier to take off smoothly going up a hill, and potentially safer too (you don't have to worry about rollback even if the car behind stops too close)

I'm not sure what sensors come into play but as I tried to accelerate away the autohold feature would not let go although I was throttling on...

If your car is fitted with Auto-Hold (as opposed to HSA), then there should be a button somewhere to turn it on and off. On the Passat, it's one of the buttons next to the gear selector. In the Passat, you need to have your foot on the brake to be able to turn Auto-Hold off, otherwise the parking brake automatically engages.

Auto hold works as part of the Electric handbrake and Hill assist works with the Hydraulic braking

Have a read of this page Auto Hold Function < Technical Glossary < Innovation & Technology < Volkswagen International

I think your interpretation is slightly off - the auto hold actually uses the brake hydraulics to maintain braking pressure to hold the vehicle stationary. Further down the paragraph from your link:

The system is operated via the ABS/ESP hydraulic unit.

So functionally, auto-hold works like the parking brake, and will cause the electric park brake to engage automatically if you try to turn it off with the button on the console without your foot on the brake, or if you are stationary with your foot off the brake for too long. Mechanically, however, this function is implemented using the same hydraulics as the foot brake.

For safety reasons, the function always has to be reactivated by means of a button to the left of the gear lever.

This description from the same page is either slightly inaccurate, or outdated - Auto-Hold can be manually turned on each time you start the car via the console button, OR you can set it to be on by default through the MFD menu (this applies to the Passats with the white MFD, not sure about the earlier red MFDs).

[AllBlack]

No, the clutch will not start engaging until the system detects a change in accelerator position. At that point the brake will disengage and the clutch engage.

With a DSG, you do NOT want to try and hold the vehicle n the hand brake only as now the clutch will try and engage. You have to have your foot on the brake where a sensor will disengage the clutch.

Just checked this theory, and on flat ground, auto hold OFF, once the foot brake is released, engine starts and the car kicks into gear and it moves off. Foot no where near accelerator. just creeps forwards on 800rmp.

[Hillbilly]

Just checked this theory, and on flat ground, auto hold OFF, once the foot brake is released, engine starts and the car kicks into gear and it moves off. Foot no where near accelerator. just creeps forwards on 800rmp.

Same as mine.

I never use auto hold and on a hill would use the handbrake as when you put foot on accelerator it disengages, provided you have your seatbelt on and connected

So would sort of work in a similar fashion to hill hold.

[AllBlack]

So it seems I'm now able to answer my own question. Today I tried using auto hold on a slight incline. Here's what happened.

Took foot off the brake, engine started, auto hold held the car still. Tapped the accelerator very briefly and the brake released, car rolled back just a fraction before creeping forward in first gear. Guessing this means clutch isn't burning!