vRS TDi DSG not engaging back in gear in Eco mode after coasting!

[Neily03]

Coasting in-gear creates mechanical drag, effectively slowing you down and thus requiring more throttle activation to keep pace with traffic or maintain speed. Depending on the engine map additional fuel may also be injected at higher than idle rpm. Coasting in-gear will always use more fuel.

Wrong, 'coasting' in gear uses NO fuel, it's shut off completely as there's no need for any.

[andyvee]

Wrong, 'coasting' in gear uses NO fuel, it's shut off completely as there's no need for any.

 

But unless you are going downhill you will decelerate more, so takes more fuel to bring you back up to speed is the theory. Not saying I agree with the theory mind.

[Orville]

Wrong, 'coasting' in gear uses NO fuel, it's shut off completely as there's no need for any.

That is not entirely correct because all engine management systems will be begin refuelling before reaching idle state. Typically this can happen anywhere between 1200-1800rpm, but I concede (also see above apology) that most modern cars do coast without using fuel above these ranges.

[TudorM]

Orville, you are thinking of carburetor engines. Those behave the way you initially mentioned. Hard to find those nowadays tho.

[Orville]

Orville, you are thinking of carburetor engines. Those behave the way you initially mentioned. Hard to find those nowadays tho.

I'm getting old my dear boy. .

[sworrall]

anyway, back to the ops original post...

 

Ive also had the same thing in mine but its not involved a roundabout and can be replicated at any time with the right road speed.  

 

Ive found that when in ECO and going about 40-45mph if the box is in 6th then goes to E and coasts when I depress the throttle to then speed up or try and keep a constant speed the rev counter (which has been at 1000rpm whilst coasting) starts to "bounce" off 1000rpm to 1500rpm and wont re-engage and thus the car just starts to slow down.

 

the only way ive found to get around it is to really put your foot down which ends up with you shooting forward slightly as its gone to 3rd or 4th or applying the brake.  Not ideal when going down the road with a stream of traffic behind you :(

 

Ive asked the dealer service chap about it and they just said its the mechatronic unit trying to decide what gear to pick and normal :( :(   not the best response ive had to a service enquiry imo.  I might make a video of it and show it to the dealer owner to see what they think.

 

other than that my DSG ownership has been great.

 

_____________

 

Feel free to continue blabbbing on about how the thousands of new DSG octavias being produced are now illegal as they disengage the clutch and "coast" to save fuel.  Ill expect a visit from plod sometime soon im sure...

[TheWanderer]

All this does is remind me NEVER to engage it.

[LewJo]

It is illegal to coast out of gear, I've just checked it.

What was your source? I find it hard to believe that manufactures would put a feature on their cars that makes the driver commit an offence.

This fault has persuaded me that Eco mode will never be used in my car. The potential for it to cause an accident is an unacceptable risk in my book.

Lewjo (Joseph)

[bouff34]

It is illegal to coast out of gear, I've just checked it.

Under which bit of legislation is it illegal?

[J8mbo]

I used to be a Vehicle Specialist and also taught people how to drive said vehicles.

 

Coasting was not permitted as it would remove some of the control from the driver as below. For example taking too long trying to find a gear (too long in neutral whilst still moving forward) would be a big black mark as the driver would be coasting.

 

Reasons for not coasting from GOV.co.uk

 

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.

They are the usual ones but with electrical steering and DSG gearboxes, which should select a gear easily (not so in the cases above) coasting probably isn't really an issue.

 

The difference is the DSG gearbox has pre-selected the neutral, where as in a manual box, you would physically knock the gear lever into neutral = naughty.

 

You can clearly coast without reprisal if the computer does it for you.

[bouff34]

I used to be a Vehicle Specialist and also taught people how to drive said vehicles.

 

Coasting was not permitted as it would remove some of the control from the driver as below. For example taking too long trying to find a gear (too long in neutral whilst still moving forward) would be a big black mark as the driver would be coasting.

 

Reasons for not coasting from GOV.co.uk

 

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.

They are the usual ones but with electrical steering and DSG gearboxes, which should select a gear easily (not so in the cases above) coasting probably isn't really an issue.

 

The difference is the DSG gearbox has pre-selected the neutral, where as in a manual box, you would physically knock the gear lever into neutral = naughty.

 

You can clearly coast without reprisal if the computer does it for you.

 

 

This is taken from the Highway Code BUT is only advisory and NOT a legal requirement. If it was it would be phrased as you MUST or you MUST NOT and there would be a reference to the legal basis underneath the point (as there are under other sections of the code). I still don't see that anyone can say it is specifically ILLEGAL to coast unless anyone can produce an act and section which says it is so.... I agree that it isn't good practice but that is not the same thing.

 

(As an aside, if coasting was made illegal then it wouldn't be possible for your car to be towed using a tow rope.)

Edited 1 November, 2013 by bouff34

[J8mbo]

Whether you put the car into neutral or not, you must be in full control of the vehicle. Engine running or otherwise.

 

Towing a car is clearly a breakdown situation and that journey should be kept to a minimum where possible. The 'towed' driver should remain in full control of that vehicle.

 

I remember in my youth, me and some mates were in the back of a Hillman Hunter. As we approached a hump back bridge Trev took the keys from the ignition and threw them onto the back seat.

 

Unfortunately, his aim was off and the keys went down a missing speaker hole on the parcel shelf!

 

The steering locked because the key was out and the brakes stopped working as he frantically pumped the pedal. Luckily, we managed to reach into the boot to get the keys.

 

The car mounted the pavement/ grass verge and nearly went through a fence before Trev got the key back in and re-started the engine.

 

Now that was extreme coasting!

[Chunkstar]

Porsche 911 has this feature ,and worked well but never did it on or near an island surely you should be "on the brakes or throttle " so should never happen ?

[TudorM]

For guys who already have their cars, can you select Eco from the mode button but have the coasting function disabled from the options? So if you want it, you can still use Eco but without the fiddly bit which is coasting?

[sworrall]

For guys who already have their cars, can you select Eco from the mode button but have the coasting function disabled from the options? So if you want it, you can still use Eco but without the fiddly bit which is coasting?

nope, no option to disable

[conn]

Sounds like a software issue to be really honest. As of my own experience I always like to be in gear. No coasting - not ever (been driving manuals and automatics). In the urban area I would say that being in gear and decelerating using the engine can save you more fuel compared to coasting. Why? Because you will start decelerating always at the same time - does not really matter if you coast out of gear or decelerate using engine. For example you see you need to come to complete stop after 200 meters down from 50 km/h. Which saves you more fuel - coasting or decelerating in gear (oh and which of those burn more breaks)?. What I am saying is that if you want coasting to be more effective you need to roll farhter away to be as effective.

 

For notes injection engines do not consume fuel over around 2000 rpm decelerating in gear. If you are decelerating at 1500 rpm then you will consume a little, but way less compared to coasting.

 

Oh and driving down a long hill you are better off being in a right gear where you do not gain speed nor decelerate - 0 consumption. On the mountains - you HAVE TO be in gear, otherwise you will just burn out your breaks. Simple as that.

 

 

And over all why did they implement that ECO anyway. Normal for every day driving and Sport when you want to get a little bit kinky.

 

 

By the way this is my build week of 1.8 Elegance DSG with loads of equipment - weeeeeee.

[TudorM]

Imo, getting used to engine braking is useful as future preparation for driving electric cars. The regenerative braking on those is so powerful, you skip using the brakes much more than on ICE cars. But I'm going off topic again...

[Dodgy]

Interesting that people posting on an enthusisasts seem to think they have more intimate knowledge of the pros and cons of coasting than the designers of the system over at VAG.

[andyvee]

Anyway, back to the subject......

 

I tried this on the way in to work today, and it worked flawlessly, both in traffic and at motorway speeds.

 

I found it selected the correct gear on re-engaging and only needed a slight press of the accelerator to re-engage gears.

 

One odd thing is that it doesn't return to coasting after a gentle tap of the brakes without a gentle prod and release of the accelerator, it seems to assume you still require engine braking and stays in gear.

 

Can't see that Eco mode made the slightest bit of difference to the fuel economy on my regular drive, hardly a scientific test though!

 

Might try it on a longer run and see what happens.

[Anddenton]

Interesting that people posting on an enthusisasts seem to think they have more intimate knowledge of the pros and cons of coasting than the designers of the system over at VAG.

 

Problem is I think the designers over at VAG have come up with this as a way of increasing fuel economy and decreasing emissions in the official tests without considering real world driving where coasting for long periods is not really possible unless you have long stretches of level or slightly downhill road. Coasting in the UK is usually coming up to traffic lights/junction where you coast for a bit then use the breaks, so no benefit here, or coasting down hills where this new feature will allow the car to run away and you will need to be on the break all the way down = more fuel used and you have break fade at the bottom when you need to stop.

 

Probably works great on a rolling road but around town or on A/B roads (And probably most UK motorways) I'll remain a sceptic for now.

[Phil-E]

Definitely not right.

 

Surely the car should re-engage drive when touching the throttle? How a dealer can say this is 'normal' is beyond me!

 

Imo, getting used to engine braking is useful as future preparation for driving electric cars. The regenerative braking on those is so powerful, you skip using the brakes much more than on ICE cars. But I'm going off topic again...

 

And I think you are a little off with this one.

 

Drove a Toyota Yaris Hybrid the other day.

 

You get NO regenerative braking when in 'D'. The engine does shut off when coasting but no regenerative braking. The only way you get this is to shift the gear leaver into 'B' mode. It then drive like a normal ICE car in gear giving you 'engine' braking when you let go of the throttle.

 

So it seems even hybrid cars are using the whole coasting for longer saves fuel theory.

 

Phil

[philbes]

Coasting with the car in neutral would be an instant fail on the IAM Advanced Driving test.  Indeed I know of a candidate that failed within 5 minutes of starting the test because he depressed the clutch to roll over each of a series of speed bumps.  I am meeting an IAM examiner at a training course tomorrow and will discuss this with him.

[TudorM]

Then tell him about this whole DSG gearbox and coasting out of gear in ECO and see what he thinks of it. Quite curious...

[Anddenton]

 

So it seems even hybrid cars are using the whole coasting for longer saves fuel theory.

 

Phil

 

Bit different on a hybrid as the engine is cut so no fuel is used. On a petrol/diesel when coasting (Clutch down/out of gear) the engine is running so using fuel to idle, coasting with clutch up then no fuel is used so better to do this unless you are coasting over a long distance on level road which I guess doesn't happen very often.

[Phil-E]

Yeah curious to hear an IAM instructors thoughts on it.

 

Bit different on a hybrid as the engine is cut so no fuel is used. On a petrol/diesel when coasting (Clutch down/out of gear) the engine is running so using fuel to idle, coasting with clutch up then no fuel is used so better to do this unless you are coasting over a long distance on level road which I guess doesn't happen very often.

 

But in the Hybrid you can use regenrative braking which drives the motor as a generator to pump power back to the batteries. This produces drag similar to engine braking.

 

In normal 'D' mode the Yaris hybrid didn't do this and just coasted with engine off and motor not engaged.

 

Phil