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DSG downhill in manual......


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I used to put my manual car into 'n' and coast while going down hill until I got told that you can actually be done by the police for it, under the charge of 'not being in full control of your vehicle'. I have no idea how they would be able to tell and if this is indeed true. It was the guy at my SAC that told me this.

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It is not engine braking though is it, it is not some old style diesel.

The Sparks are sparking, the fuel is fueling and the engine is still running, maybe not requiring much fuel but it is still getting fuel.

Sorry George, but I'm afraid you are wrong...

From Wikipedia...

"The term 'engine braking' refers to the braking effect caused by the closed-throttle partial-vacuum in petrol (gasoline) engines when the accelerator pedal is released. While some of the braking force is due to friction in the drive train, this is negligible compared to the effect from the vacuum.

When the throttle is closed, the air flow to the intake manifold is greatly restricted. The concept can be illustrated by the amount of effort required to blow/suck through a thin tube vs. a wider one. It is the work the engine has to do against this restricted air flow that provides the braking effect.

Diesel engines do not have engine braking in the above sense. Unlike petrol engines, diesel engines vary fuel flow to control power, rather than throttling air intake and maintaining a constant fuel ratio as petrol engines do. As they do not maintain a throttle vacuum, they are not subjected to the same engine braking effects."

My point is that the engine, under these conditions, uses a negligible amount of fuel, whereas the same engine, ticking over, uses more as it has to provide enough fuel to keep it running without the assistance of momentum going down hill in gear

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Read what you posted in #23. that is what i was answering to.

 

Is it not good that technology moved on,

what are Wiki saying now on Energy Generation, Battery charging etc, Energy Harvesting,

as we all know there is no way of generating energy without using energy, other than gravity assisted.

Petrol engines require Fuel , Air and Fire.

 

Diesel Engines require Fuel & Heat & that gives the Compression to keep them going, once running you do not need the Electricity.

 

VW now have Cylinder Deactivation or Cylinder on Demand, even they have not have all cylinders not firing,

other than with stop start when the engine shuts off and requires no fuel.

If they can run down hill and use no fuel by shutting down cylinders, that will be coming to a showroom near you soon.

 

Just now we are talking these Euro 5 Emission Gasoline Engines.

Edited by goneoffSKi
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Read what you posted in #23. that is what i was answering to.

 

as we all know there is no way of generating energy without using energy, other than gravity assisted.

Exactly.

Going downhill is using gravity.

Thanks for proving my point :)

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But the engine is using fuel no matter how little,

 

not as said. in #23

"engine braking uses no fuel at all as the momentum of going down hill turns the engine".

 

To see if this is actually true,

maybe plug into the OBD2 and use the readings and see what fuel is being used.

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On a dsg it may use fuel* however manual cars have been switching injectors off for about 20 years

*it may not , I don't know enough about the mapping on modern dsg equipped cars

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Same engine, just the gearbox that's different. No reason to suggest the fuel injection doesn't cut fuel in the same way.

Which is what I meant in my original post

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Hello all.

Still getting used to the DSG,and I have a quick question.....

Going downhill in manual 4th gear,the revs suddenly dropped to idle,i was braking at the time,then when I let off the brakes, the revs went back up to around 3k RPM as they were...

Does this seem normal......I hope so.......

Thanks all......

 

Latest 7 speed DSG have freewheel function to save fuel.

 

If it freaks you change in to sports mode.

 

Q5/Q7 boxes have had it for a few years now.

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Has the DQ200 DSG 7 Speed Twin Clutch had the Service Campaign Field Action since the Service Campaign Started last May?

 

The Synthetic OIl replaced with Mineral Oil & the DSG Software Updated & a Sticker in the boot to show it is done.

Is this what was done yesterday,

or did they just reset the ECU yesterday because they found no Fault Codes?

goneoffSKi..

No oil changed in the DSG,they just re-set the control unit for the gearbox..(or car ECU)

If it needed the oil changed surely they would be aware and do it??

Cheers....

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Would they and would they?

 

Just call Skoda UK CS and ask if your car comes up as requiring the DSG Service campaign, or has it already been done.

http://briskoda.net/forums/topic/314923-fabia-recall/page-9

 

I imagine they were at the Cars ECU via the OBD2, checked for Codes and left in clear.

Edited by goneoffSKi
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Even though I have a 2011 7 speed dry clutch I adopt my own free wheel function by, on a clear road, shift the lever in to neutral down long gentle hills to preserve momentum (both enegry and Tescos fuel) and then re-engage drive when I get on the flat or start the climb.  Helps me get close to the 45 mpg combined figure or even the 55 mpg extra urban if one is feeling keen to get up to the extract the max for the Fabia 2 VRS.

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Neutral isn't needed to get figures like that. The car doesn't fuel when coasting. That's in D or in an appropriate gear in manual mode. Of course if you are in too low a gear while coasting the effect of engine braking will be greater but why shift to neutral for the same effect when you'll get it by being in a high gear anyway?

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Neutral isn't needed to get figures like that. The car doesn't fuel when coasting. That's in D or in an appropriate gear in manual mode. Of course if you are in too low a gear while coasting the effect of engine braking will be greater but why shift to neutral for the same effect when you'll get it by being in a high gear anyway?

 

Free-wheeling has always helped as is more efficent than keeping it in gear due to negating the frictional losses of running with it in gear and turning the engine over faster than it needs to be and hence VAG have been introducing it in the more modern DSG gearboxes.

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