Engine brake,DSG

[WelshGas]

I got sick off dabbing the brake then dabbing the throttle more so when going down hill so i went back to normal function and doing what i use to in my golf estate,drop it into neutral and coast then back in gear much easier after 50000 miles of doing that my dsg was still perfect.

Your choice. Your DSG box was OK at 50k, and what about at 60k or 70k. But no doubt you sold it on before then.
I'm only telling you how it works. It is illegal to disengage the engine from the gear box by putting the gear box in Neutral VW and other manufacturers get round this by using the Clutch pack in a fail safe mode in the Coast function as the Clutch Pack will automatically engage if there is a problem.
One day you could get brake fade and the DSG box fails to select the correct gear in time and there is a sharp L hander in front of you.

 

[gregspam]

I have a manual but had a DSG on loan when mine went in for the roof repair. When the loan van was dropped off it had the coasting function enabled which I found it a little disturbing going downhill. The way it gathered pace on moderate and steep hills gave the sensation of the van 'running away with itself' and meant I was constantly dabbing the brakes when I wasn't used to having to.

It expect it depends a lot on driving style what behaviour is desirable. I'm used to using engine braking to control my speed, so the interference of the coasting function with my expected default behaviour made it feel counter-intutitive. If i'm easing off the accelerator (downhill or otherwise) it's because I want to go no faster, not pick up pace. I switched the Coast function off and felt much more in control. I only had the DSG for a short period so didn't notice the behaviour the OP mentioned, but I can see how if you are coasting downhill and expecting to control speed by dabbing the brake then engine braking kicking in could be unwelcome. Equally I can see why that software makes the safe decision to provide engine braking to alleviate the potential for brake fade on long descents.

So the intelligence of the DSG boxes has its limits, but we don't want to set off another DSG vs Manual thread now do we...

 

[motacyclist]

I'm used to using engine braking to control my speed, so the interference of the coasting function with my expected default behaviour made it feel counter-intutitive.

I was the same when I first discovered that the DSG box had this feature, but after a few days you get used to it and can use it to it's advantage.

The engine braking doesn't kick in suddenly, a light touch on on brake (without actually applying the brakes) will just re-engage the engine in the same gear it was in prior to lifting off. If this doesn't control the speed enough then just apply the brake as you would normally, this will then cause the box to change down and assist the brakes to reduce speed; dependant on the steepness of the descent the engine revs may rise appreciably as described in an earlier post.

Additionally, slowing down in this fashion will also cause the alternator to take the opportunity to recharge the battery at maximum output. I discovered this after studying the display on the control unit and was puzzled to see that often there was a drain, not a charge, on the battery when travelling at a constant speed. This was because the technology was reducing the load on the engine to reduce fuel consumption; the charge being subsequently replaced on downhill sections when the control unit would show 20 amps going in to the battery.

BTW I don't recommend watching the control unit display whilst driving!

 

[gregspam]

The engine braking doesn't kick in suddenly, a light touch on on brake (without actually applying the brakes) will just re-engage the engine in the same gear it was in prior to lifting off.

My point was that I'm used to how easing off the accelerator behaves and I didn't want to have to move my foot and dab the brake to get that behaviour back (when the roads are clear I often have little need to touch the brakes). When I'm in the right gear for the gradient (of course the DSG makes that choice for me in full auto mode) I don't expect to go faster when I ease off the accelerator and that's often what happens on inclines with the coasting function. But each to their own, it is a setting after all.

 

[T6 CFO]

Very interesting discussion as I was clueless on the coast function. I can say though that I have been on a few driving courses with rather aggressive instructors. I hate to think of the consequences had I stuck the gearbox into neutral


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[ROKET]

Your choice. Your DSG box was OK at 50k, and what about at 60k or 70k. But no doubt you sold it on before then.
I'm only telling you how it works. It is illegal to disengage the engine from the gear box by putting the gear box in Neutral VW and other manufacturers get round this by using the Clutch pack in a fail safe mode in the Coast function as the Clutch Pack will automatically engage if there is a problem.
One day you could get brake fade and the DSG box fails to select the correct gear in time and there is a sharp L hander in front of you.

Thanks Welsh gas noted.The problem what made it worse is my brake pedal when cruising seem to go down a couple of inches and not much feel and braking harder then needed and going down to cornwall it got tireing and felt a little out of control.I Took my cali to have the brakes checked they said it was normal is your 180 the same,my golf was a solid feel.cheers

 

[WelshGas]

Thanks Welsh gas noted.The problem what made it worse is my brake pedal when cruising seem to go down a couple of inches and not much feel and braking harder then needed and going down to cornwall it got tireing and felt a little out of control.I Took my cali to have the brakes checked they said it was normal is your 180 the same,my golf was a solid feel.cheers

No, my brakes feel fine. Except on steep hills I wouldn't even know the Coast function was activated if it wasn't for the fact that the revs dropped to idle and the Gear indicator on the Dashboard display shows just D or S.
I certainly do not get any change in the brake "bite" position or amount of force required. Does that happen ALL the time or only after a period of travel?

 

[Freeley]

I've always had to stand on the brakes on mine, it was a bit disconcerting at first but have got used to it. Never had to do an emergency stop though!

Sent from my Galaxy S6

 

[motacyclist]

Odd to hear that about the brakes, the two Cali's I've had have been fine, maybe they have changed the amount of servo assistance?

 

[CYCLOPATH]

ROKET you don't say how old your van is.
Mine is 2015. I find the brakes very powerful . I have to be gentle, which is fine, or the van slows up very quickly!
Looking at the front discs, I have 18 inch thunders, and the discs are almost as big as the wheels, which goes some way to explain it
From what you describe....not much feel......a little out of controll......it doesn't sound right to me.
Was your garage used to the 180 Cali, which is different to the transporters. I know my local VW van garage, a non Cali one, doesn't seem to know some of the specifics........

 

[leightonjthomas]

Personally I would never free-wheel a vehicle, manual or automatic, in neutral because of the possibility of loss of control if there were even the slightest of delays in re-engaging the correct gear.
We are now in our third year of Cali ownership and have enjoyed driving all over the UK and much of Europe. I have always been a lover of Cruise Control and have always engaged it as much as possible. However, it was only after reading Welshgas's advice on the coasting function that I starting adjusting my use of cruise. Previously I had just stuck it in cruise and left it there for mile after mile of motorways, whatever the terrain. Now, as I start descending some of the long, rolling hills of France, Portugal (or even the M4!), I dab the brakes gently to disengage cruise and then touch the throttle before immediately releasing, allowing it to coast downhill. Usually the speed will increase slightly due to the slope then, just as it is levelling out and the speed nears the original cruise speed, I press the reset button and it reverts seamlessly to cruise control.
Previously, as I say, I would have left it in cruise with the gear-select reading showing D7, whereas in coast mode it shows D. The main benefit has been in mpg which has noticeably improved, even on relatively short journeys.
I have never felt out of control and I would not attempt to use on very steep hills where I am more than happy to utilise the engine break function.
Having driven countless types of vehicles, including heavy goods, over almost forty years I am very definitely still learning to get the best out of my beloved Cali.

 

[sidepod]

Are you guys aware how brake servo vacuum is created on a diesel?
It's probably better to keep the engine spinning..

 

[CYCLOPATH]

Sidepod, tell us about servo vacuum

 

[CYCLOPATH]

Leightonjthomas,
I have been driving like you describe, except , if you just push the cruise controll lever on top of the stalk half way to the right, it temporarily turns of cruise controll, but doesn't cancel the last settings, so you can coast in D,
then click the side button on the stalk up to go back to previous speed, or down to set it at current speed
It just saves all the dabbing, and making brake lights flash

 

[sidepod]

Brake servo vacuum on a diesel is created by a pump driven off the engine ( unlike a petrol motor that uses intake low pressure across a diaphragm)

Long descents on idle may well overwhelm the servo. Result, almost no brakes , unless you drive like Kimi ( two foot braking).

 

[leightonjthomas]

Leightonjthomas,
I have been driving like you describe, except , if you just push the cruise controll lever on top of the stalk half way to the right, it temporarily turns of cruise controll, but doesn't cancel the last settings, so you can coast in D,
then click the side button on the stalk up to go back to previous speed, or down to set it at current speed
It just saves all the dabbing, and making brake lights flash

I didn't know that and will certainly use from now on as I haven't liked the thought of the brake lights flashing. I thought that the switch would only turn it on or off and, therefore, I'd lose the set speed.
Many thanks, Cyclopath.

 

[WelshGas]

Are you guys aware how brake servo vacuum is created on a diesel?
It's probably better to keep the engine spinning..

In "Coast" mode the engine is idling and the EMU is monitoring and controlling everything. It will adjust engine revs if necessary.

 

[benArrayx]

In my experience in my diesel Audi A4 engine at idle is sufficient for the brake servo to work - tested this the other day in heavy traffic crawling down a steep mountain road with engine off, then on again when brakes stated to fade (due to non running servo).

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[sidepod]

In my experience in my diesel Audi A4 engine at idle is sufficient for the brake servo to work - tested this the other day in heavy traffic crawling down a steep mountain road with engine off, then on again when brakes stated to fade (due to non running servo).

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And you managed to steer it without power steering ?
Of course the servo will fade with no engine. Crawling along isn't exactly pushing the brakes system is it?
Only a nutter would coast downhill in neutral.

 

[benArrayx]

Steering was incredibly heavy but just doable, it was mainly straight though. I'm talking about going at maybe 1mph max, literally crawling forward in v. heavy traffic. I wouldn't do it any faster than that. Brakes continually on, more or less depending on if I wanted to roll or not. Not a recommended thing to do, but I'd already been sat for a long time burning diesel and polluting the mountain for no good reason... No stop/start on that car

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[briwy]

The servo does not have any effect on brake fade which is usually due to excessive heat build up. In extreme cases the brakes can fail completely and the brake fluid can boil.
This why engine braking is used on long descents on a big gradient, more normally associated with HGVs.
All the servo does is reduce the effort you have to exert on the pedal, so if you have brake fade the brakes won't work properly whether the servo is operative of not.

 

[ROKET]

No, my brakes feel fine. Except on steep hills I wouldn't even know the Coast function was activated if it wasn't for the fact that the revs dropped to idle and the Gear indicator on the Dashboard display shows just D or S.
I certainly do not get any change in the brake "bite" position or amount of force required. Does that happen ALL the time or only after a period of travel?

The way i could describe my brakes is if i press slowly they have feel and respond quickly and if i have to press the brakes quickly the pedal goes down 2 inches and lose the feel so i brake to hard ,i think it is a servo problem. When i go down hill in gear of the thottle and need to check my speed i go into manual and change down accordingly with short dabs on the brake pedal when needed not over short distances my golf had the same original brake pads at 50000miles and that is with a lot of trips over holme moss so i will not be getting any brake fade.My cali is a 2015 180 dsg with 7000miles on the clock .cheers

 

[WelshGas]

The way i could describe my brakes is if i press slowly they have feel and respond quickly and if i have to press the brakes quickly the pedal goes down 2 inches and lose the feel so i brake to hard ,i think it is a servo problem. When i go down hill in gear of the thottle and need to check my speed i go into manual and change down accordingly with short dabs on the brake pedal when needed not over short distances my golf had the same original brake pads at 50000miles and that is with a lot of trips over old moss so i will not be getting any brake fade.My cali is a 2015 180 dsg with 7000miles on the clock .cheers

All I can say is that I get progressive braking from the time I press the brake pedal. If you are not happy then maybe persuade your Dealer to have someone go on a test drive with you to try and replicate this rather than depend on the Diagnostic computer.

 

[benArrayx]

That definitely sounds like a problem Roket.

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[briwy]

Sounds like they need bleeding unless it's some weird thing associated with the DSG box.