Engine brake,DSG

[CYCLOPATH]

i am still learning about my gearbox.
When going down hill, it goes into coast
Which I really like, quiet and smooth
But when I brake , it drops into a lower gear, revs more and works as an engine brake.
On a steep 1 in 4, like Porlock hill , I understand,
But , for example , coming off Exmoor , a fast 1 in 6.... I managed 50 mph on my bike in the summer, .
As soon as I braked, it dropped to third. I didn't even need to use the brake
This seems wasteful, and noisy
So I have been dropping it into neutral , and coasting, and braking gently

My question
Am I doing wrong
I have a 180 with the massive discs at the front.

A previous post mentioned choosing between wrecking the engine , or Wearing out the discs.
My choice would be disk, unless there is something I don't know

 

[Freeley]

My cali is a tiptronic so I know nothing about the dsg but I would've thought it was pretty dangerous to drop it into neutral regardless of hill gradient.
For me, I leave it in auto for minor hills but drop it into manual for anything more than that as I want the engine braking

Sent from my Galaxy S6

 

[CYCLOPATH]

Why dangerous.
I have been doing it for the last thousand miles with no problems

I have been doing it in my manual car for the last 5 years
And was really pleased when I found the coast function on the DSG in my Cali.
It drops into neutral .......as long as you arnt breaking

 

[WelshGas]

Why dangerous.
I have been doing it for the last thousand miles with no problems

I have been doing it in my manual car for the last 5 years
And was really pleased when I found the coast function on the DSG in my Cali.
It drops into neutral .......as long as you arnt breaking

Have you switched the "Coast" function on. You shouldn't drop the DSG box into neutral. The gear boxes will take time to switch to the appropriate gear when you put into D. Use the Coast function instead.
You do know about the COAST function on the California? Switched on via the Dashboard Multi Function Display. If functional it will disengage the engine when you stop accelerating. As soon as you touch the accelerator or brake then the drive re-engages and the DSG is in the correct gear.
The California has "Regenerative Braking" which will use engine braking to drive the alternator thus pumping more charge into all the batteries. Using the brakes to slow such a heavy vehicle could lead to brake fade and the inevitable little mountain of flowers at the roadside.

Brakes are cheaper than an engine -True, but brake failure/fade often leads to a trip to A/E or the Undertakers, because those that subscribe to that theory and drive dependant on their brakes frequently end up in one of those places. I know, I used to certify them and speak to the relatives.

 

[2into1]

This one will run and run......almost as far as a car in a neutral coast.

Cue a massive argument about (i) if it dangerous or not and (ii) does it actually save fuel.

For me, (i)=No, (ii)=Big time

 

[pjm-84]

I always control it on the descents due to the weight. I will typically go across to manual, particularly on the steeper inclines or sports on the shallow ones.

Brakes are better but I wouldn't want to be greeted with brake fade when I needed to brake. I've had a few times over the years. I recall towing a rowing boat trailer that I controlled down a long descent and when I needed to check my revs towards the bottom there wasn't much braking to be had. I suspect the trailer brakes were not that effective.

I also cycle and have had, due to my size, numerous issues with brake fade, exploding tubes etc.

 

[Hotel California]

http://vwcaliforniaclub.com/threads/dsg-high-revs-downhill.10100/#post-94333

 

[BerndRos]

I thought freewheeling in neutral used to be illegal in the UK, on the basis that your not then fully in control of your vehicle.

Is this still the case ?

 

[pjm-84]

Rule 122
Coasting. This term describes a vehicle travelling in neutral or with the clutch pressed down. It can reduce driver control because

• engine braking is eliminated
• vehicle speed downhill will increase quickly
• increased use of the footbrake can reduce its effectiveness
• steering response will be affected, particularly on bends and corners
• it may be more difficult to select the appropriate gear when needed.

 

[CYCLOPATH]

Thanks folks, interesting.
Welshgas, I to have had to do to many cremation forms, and am not into risk taking , hence me asking the question and trying to understand.
I do have the coasting function enabled, and isn't it right to say that when you stop accelerating, then the DSG coasting mechanism kicks in, it is putting the engine , in effect, into neutral, the clutch disengages, and revs drop to under 1000. If this happens downhill, then you do indeed pick up speed.
VW can't have put that in if it was illegal , or dangerous....(oops , forgot emissions, may be they could!!)

 

[motacyclist]

Whether this feature saves any fuel or not is debatable, because the engine is ticking over using fuel when coasting whereas when the clutch is engaged on deceleration the fuel is cut off. So the jury is out on that one.

Anyway, I leave it enabled because it can be easily controlled and is useful. For example, approaching a red light or hazard in the distance I will lift off the accelerator and go into coast mode. If the light/hazard remains as I get closer a quick dab on the brake pedal will engage the engine (it is not necessary to actually apply the brakes to do this). The vehicle can then be brought to a stop on the brakes if necessary.

Going downhill on a slight slope the coast feature can be used to maintain speed without using any throttle. If the speed increases too much then a quick dab on the brake pedal engages the engine. If the van slows down too much, then rather than speed up using the engine just dab the throttle pedal and this will put the vehicle back into coast mode.

I enjoy using this feature and enjoy trying to anticipate in order to get the longest distance without actually using the engine!

 

[CYCLOPATH]

I didn't know that Motacyclist, the engine brake cuts the fuel off.
I always presumed it was still sucking fuel in, and burning it to provide the energy for the breaking.
That changes the equation quite a lot,

 

[AlanC]

The fuel will never be cut completely off. The engine will just drop to idle, this should be about 900rpm appx, as shown on the tachometer and a small amount of fuel is needed for this.

Alan

 

[CYCLOPATH]

But it doesn't Alan, it revs higher than normal
Normally it drives around 2000 revs, but down a hill with the brakes on it goes up to over 3000

 

[AlanC]

Sorry, I was thinking about the Coast Mode for that answer.

If you are in a lower gear going down hill, the fuel is still supplied but still at the idle level.

If you toggle through the display to Consumption 1 when this happens, you will see the consumption goes up in this situation. If the fuel was cut off, the consumption figure would be zero as the computer wouldn't have any fuel flow with which to calculate the consumption.

Alan

 

[WelshGas]

When you are in "Coast" mode, the engine is disengaged from the gearbox and is idling - and in this state it is using fuel to maintain the idling speed.

When you dab the brakes , "Coast" mode is switched OFF and engine braking is engaged. The engine is connected to the gearbox and the wheel speed drives the gearbox which drives the engine and thus the revs increase. You are now utilising engine braking. The engine revs rise BUT - NO FUEL is injected into the engine. This is controlled by the Engine Management Unit (EMU) the engine is basically drawing in air and compressing it thus producing a Retardation Force ie: Engine Braking
The EMU also drops a gear to allow the engine to rev higher and thus more engine braking. Also just read that the Turbo also produces an element of exhaust back pressure.

 

[AlanC]

I stand corrected.

Alan

 

[CYCLOPATH]

So
Why is it any worse for me to disengage the engine by slipping into neutral, and use the brakes gently?
And if I feel the brakes are fading, or even just need to stop a little harder, then flip it back into gear

I don't drive or descend on the edge atall, going down Porlock hill, or alp d huez is a different matter, but on gentle slopes ?

 

[WelshGas]

I stand corrected.

Alan

No, I had to do a lot of Googling and reading. A normal, basic diesel has very poor engine braking effect compared with a petrol engine. But modern diesels with turbos , EGR valves and EMU can now give as good if not better engine braking.

 

[motacyclist]

There's a Wiki article on engine braking here

 

[WelshGas]

So
Why is it any worse for me to disengage the engine by slipping into neutral, and use the brakes gently?
And if I feel the brakes are fading, or even just need to stop a little harder, then flip it back into gear

I don't drive or descend on the edge atall, going down Porlock hill, or alp d huez is a different matter, but on gentle slopes ?

N on the DSG box actually physically disconnects the engine from the DSG box.
COAST function does not physically disconnect the engine from the DSG box but does allow the Clutch pack to disengage, but the fail safe position is Engaged.
Also the EMU ensures that the DSG box is in the correct gear when COAST is disabled by braking or accelerating.
Going from N to D then there will be significant lag while the EMU and DSG electronics determine and change to the correct gear.

 

[WelshGas]

There's a Wiki article on engine braking here

Trouble is that article has very little about modern small Diesel engines. It tends to concentrate on Jake and Exhaust brake systems found on big HGV diesels.

 

[pjm-84]

i always wanted a jake brake!

https://www.bing.com/videos/search?...&mid=4BE4381F1836CC76928D4BE4381F1836CC76928D

 

[GrannyJen]

I try not to break my engine,

but it does sometimes seem to get terribly rowdy and busy,

I just think of all that lovely cleaning of the DPF it's doing....

Happy Engine breaking and new year everyone xxxxx


Jen

 

[ROKET]

When you are in "Coast" mode, the engine is disengaged from the gearbox and is idling - and in this state it is using fuel to maintain the idling speed.

When you dab the brakes , "Coast" mode is switched OFF and engine braking is engaged. The engine is connected to the gearbox and the wheel speed drives the gearbox which drives the engine and thus the revs increase. You are now utilising engine braking. The engine revs rise BUT - NO FUEL is injected into the engine. This is controlled by the Engine Management Unit (EMU) the engine is basically drawing in air and compressing it thus producing a Retardation Force ie: Engine Braking
The EMU also drops a gear to allow the engine to rev higher and thus more engine braking. Also just read that the Turbo also produces an element of exhaust back pressure.

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.