Auto hold - DSG - burning clutch?

[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.

[Guest001]

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!

[Guest001]

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!

Same would happen if you used the handbrake. Might be slightly rougher release though as the brakes tend to pop off quickly. Will try mine tomorrow on the only incline for miles in our area