Burning RUBBER smell.

Amarillo said:
What happens to those T6 vans where the driver, to keep weight down for fuel economy, never refuels above 1/4 tank?


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There is a member on the T6 forum who deliberately kept is tank low to stop regeration happening in an attempt to improve mpg.
Well eventually he had both the dpf light and the mil light on as it was stuck in limp mode.
He had to call out VW Assist who carried out a forced regeration on his driveway and said it was touch and go as to whether it was going to clear otherwise it would have been a replacement DPF not covered by warranty.
 
I'd like to understand what is really behind this 1/4 of a tank advice.
The posts refer to insufficient fuel cooling when below 1/4 tank..... This seems to imply that the fuel in the tank gets heated when the dpf regenerates?
Why / how is that happening? I know extra fuel is used to generate the extra heat to burn the soot, but unless fuel is being returned to the tank, the explanation makes no sense.
I'm aware my attempts to understand this may be complete b*ll*ocks, but I hope someone can explain what is going on.

I'd be putting up a big fight with vw if they try and tell me I'm to blame for not following a procedure they haven't told me about.
 
2into1 said:
I'd like to understand what is really behind this 1/4 of a tank advice.
The posts refer to insufficient fuel cooling when below 1/4 tank..... This seems to imply that the fuel in the tank gets heated when the dpf regenerates?
Why / how is that happening? I know extra fuel is used to generate the extra heat to burn the soot, but unless fuel is being returned to the tank, the explanation makes no sense.
I'm aware my attempts to understand this may be complete b*ll*ocks, but I hope someone can explain what is going on.

I'd be putting up a big fight with vw if they try and tell me I'm to blame for not following a procedure they haven't told me about.[/QUOTE

The fuel is pumped around and around and around the system it is a full return system a tank of diesel flows around the system roughly once every two minutes. As dealers we have be advised to tell all of our customers and a supplement for the owners manual will be issued by vw at some point. It is also to do with the fact that depending on where you are in the world you may run out of fuel if there is not a fuel station in range as more fuel is used during regen.
Click to expand...
 
This is from vw guru’s reply “The fuel is pumped around and around and around the system it is a full return system a tank of diesel flows around the system roughly once every two minutes”.

Well, I didn’t know that, so thanks @Vw guru .

This explains a little more
 
The fuel itself heats up due to friction in the pumps and pipes etc:. and cooled on return to the tank, nothing to do with the DPF.
When a DPF regeneration is required fuel will be pumped into the DPF to ignite, raise the temperature and burn off the trapped particulates.
 
WelshGas said:
The fuel itself heats up due to friction in the pumps and pipes etc:. and cooled on return to the tank, nothing to do with the DPF.
When a DPF regeneration is required fuel will be pumped into the DPF to ignite, raise the temperature and burn off the trapped particulates.
Click to expand...
Not sure this explains it, unless vw have realised they’ve designed a fuel system that need greater than 1/4 tank to prevent overheating (and evaporating / blowing up???) in normal operation. If that was the case, surely the engine would shut down at 1/4 of a tank, not just stop regenerating the dpf?
 
2into1 said:
Not sure this explains it, unless vw have realised they’ve designed a fuel system that need greater than 1/4 tank to prevent overheating (and evaporating / blowing up???) in normal operation. If that was the case, surely the engine would shut down at 1/4 of a tank, not just stop regenerating the dpf?
Click to expand...

Ok so the fuel travels from the tank via the lift pump through the filter then through the pressurization pump it then goes to the high pressure fuel pump from there part of the fuel then goes back down the return while the rest goes to the fuel rain part of the fuel then goes back down the return line while part of the fuel is held at 2000bar pressure in the fuel rail it is then injected by the injectors when required. The unused fuel then goes back via the leak off pipes. During DPF regen fuel is injected into the engine on the exhaust stroke and combusts in the exhaust heating the dpf up there is no direct injection into the exhaust it’s all via the injectors. The dpf can at times reach 800 degrees C however it normally operates around 650 degrees C the whole engine bay gets very hot during this process and in fact it’s not a worry of the fuel overheating it’s because the fuel is used to keep the vital components cooled if the fuel gets to hot then this cooling effect is no longer present and can lead to component failure. You can drive your vehicles down past a quarter of a tank on a journey that’s fine however as soon as possible it needs to be refilled past a quarter. Say for instance you drive from Yorkshire to Cornwall and you have a quarter of a tank left then you think oh that’s ok im doing local trips while I’m down here and I will refuel before I go back, unbeknown to you just before you stoped the dpf was about to start a regen phase ( remember a T6 will go into regen ever two hours of driving accumulative) you start up drive your van for 5 miles stop do the same again and again the ecu has realized you have less than a quater of a tank and will not allow regen to start now you are clogging up your dpf. If the vehicle starts a regen process it needs to finish if you are above a quarter of a tank the process starts you are using more fuel you stop just below a quarter the ecu will try to finish the process it started even under a quarter to complete the cycle you drive short trips the engine ecu allows it because the fuel temperature is within spec and the system has to carry out either full or partial regen because the process has started there is no fuel station near, because the fuel burn rate is so high during regen you don’t have enough fuel to make the fuel station and have to call the AA. I know what options I would prefer for the sake of £20
 
Cripes, when I had an Austin Seven, I thought it was complicated when they moved the gravity fed fuel tank from the bulkhead to the rear of the vehicle, hence requiring pumping.

We asked for an explanation about what was going on and we certainly got it there!
Thanks again Vw guru for that very extensive technical bulletin.
 
Thanks for taking the trouble to post such a detailed explanation. Bit of an eye opener really. Been reading up on this elsewhere and it seems fairly common to have a 1/4 tank cut-off, so not just VW. We live and learn.
 
Vw guru said:
Ok so the fuel travels from the tank via the lift pump through the filter then through the pressurization pump it then goes to the high pressure fuel pump from there part of the fuel then goes back down the return while the rest goes to the fuel rain part of the fuel then goes back down the return line while part of the fuel is held at 2000bar pressure in the fuel rail it is then injected by the injectors when required. The unused fuel then goes back via the leak off pipes. During DPF regen fuel is injected into the engine on the exhaust stroke and combusts in the exhaust heating the dpf up there is no direct injection into the exhaust it’s all via the injectors. The dpf can at times reach 800 degrees C however it normally operates around 650 degrees C the whole engine bay gets very hot during this process and in fact it’s not a worry of the fuel overheating it’s because the fuel is used to keep the vital components cooled if the fuel gets to hot then this cooling effect is no longer present and can lead to component failure. You can drive your vehicles down past a quarter of a tank on a journey that’s fine however as soon as possible it needs to be refilled past a quarter. Say for instance you drive from Yorkshire to Cornwall and you have a quarter of a tank left then you think oh that’s ok im doing local trips while I’m down here and I will refuel before I go back, unbeknown to you just before you stoped the dpf was about to start a regen phase ( remember a T6 will go into regen ever two hours of driving accumulative) you start up drive your van for 5 miles stop do the same again and again the ecu has realized you have less than a quater of a tank and will not allow regen to start now you are clogging up your dpf. If the vehicle starts a regen process it needs to finish if you are above a quarter of a tank the process starts you are using more fuel you stop just below a quarter the ecu will try to finish the process it started even under a quarter to complete the cycle you drive short trips the engine ecu allows it because the fuel temperature is within spec and the system has to carry out either full or partial regen because the process has started there is no fuel station near, because the fuel burn rate is so high during regen you don’t have enough fuel to make the fuel station and have to call the AA. I know what options I would prefer for the sake of £20
Click to expand...
What a fantastic explanation Guru.

And I did exactly the wrong thing yesterday. I left Derbyshire for London with 1/4 tank, ran the tank right down to ~1/16 then refuelled in London with 74 litres half a mile from home.

With only short trips planned this week, I’ll have to try to work out how to squeeze in a longer journey.


Follow my blog: www.au-revoir.eu
 
The Regen cycle is driving me nuts and I thought mine must be faulty as it was doing it often (drove from Alps to Calais and it kicked in as I entered the Eurotunnel Car Park)... I thought WHY NOW!?!?!? - So thanks @VWGuru for the explanation. It seems to use a hell of a lot of fuel during this process and makes me wonder if the DPF thing isn’t a bit of a pointless circle:

Develop Diesel engine to extract maximum efficiency.
Add a DPF to protect the environment.
Clean DPF every 2 hours using lots of extra fuel, reducing efficiency and creating pollution.



I’m sure I’ve oversimplified it there somehow...


Sent from my iPad using Tapatalk
 
Great info @Vw guru ! Just out of interest - why do the newer Euro 6 engines regenerate more often than the older Euro 5 engines in the T5/5.1? Is it due to increased EGR usage or maybe something to do with the AdBlue system? It seems it could potentially be a big hit on fuel economy with such regular regens.

Thanks.
Mark
 
markh said:
Great info @Vw guru ! Just out of interest - why do the newer Euro 6 engines regenerate more often than the older Euro 5 engines in the T5/5.1? Is it due to increased EGR usage or maybe something to do with the AdBlue system? It seems it could potentially be a big hit on fuel economy with such regular regens.

Thanks.
Mark
Click to expand...
Hi @markh unfortunatly it’s all to do with lowering emissions partical limits has to be lower for euro 6 so the vehicle has to regen more. EGR lowers NoX gas to a degree and the selective catalytic reduction system (adblue) reduces the box even further
 
s2bear said:
The Regen cycle is driving me nuts and I thought mine must be faulty as it was doing it often (drove from Alps to Calais and it kicked in as I entered the Eurotunnel Car Park)... I thought WHY NOW!?!?!? - So thanks @VWGuru for the explanation. It seems to use a hell of a lot of fuel during this process and makes me wonder if the DPF thing isn’t a bit of a pointless circle:

Develop Diesel engine to extract maximum efficiency.
Add a DPF to protect the environment.
Clean DPF every 2 hours using lots of extra fuel, reducing efficiency and creating pollution.



I’m sure I’ve oversimplified it there somehow...


Sent from my iPad using Tapatalk
Click to expand...
I was thinking similar myself, also economy whilst driving a T6 is "better" than T5 but it then regens every 2 hours driving, often when you park up so it uses loads of fuel regenerating whilst parked so doesn't affect the mpg figures on the mfd. Misleading emissions and mpg in my opinion.
 
I can’t believe that VW would mislead people about emissions figures, in real terms it’s creative accounting from VW to satisfy a bullsh#t target set by tree huggers who have no concept of the real world situation.
 
Perfectos said:
bullsh#t target set by tree huggers who have no concept of the real world situation.
Click to expand...
I think the idea of climate change has moved beyond the tree hugging minority into mainstream belief.

Diesel particulates are a very real problem. They rise into the atmosphere, then fall as precipitation. When this precipitation is snow, the snow is darkened, more heat is absorbed by the darker snow and glaciers retreat and the ice caps melt at an alarming rate.

The problem is solvable, just as a worldwide commitment solved the hole in the ozone layer with the Montreal Protocol.



Follow my blog: www.au-revoir.eu
 
WelshGas said:
Been mentioned before, but are the likes of VW, and others, going to buy into it for the T7?
Click to expand...

Depending on wether there will be a T7 from mermerings I here the MK 8 golf will be the last ever golf ever built
 
Amarillo said:
I think the idea of climate change has moved beyond the tree hugging minority into mainstream belief.

Diesel particulates are a very real problem. They rise into the atmosphere, then fall as precipitation. When this precipitation is snow, the snow is darkened, more heat is absorbed by the darker snow and glaciers retreat and the ice caps melt at an alarming rate.

The problem is solvable, just as a worldwide commitment solved the hole in the ozone layer with the Montreal Protocol.



Follow my blog: www.au-revoir.eu
Click to expand...

My post was not aimed squarely at the particulate issue, which as you quite rightly say is a real issue, I highlight the issue of the real world situation where manufacturers are “forced” to use creative accounting to meet a particular Short term target to enable them to “continue” to sell a product which the manufacturer have no short term practical solution or alternative and therefore is forced to continue to use a fossil fuel enabled vehicle, which has been modified to meet a particular short term target, not in fact to address the real world issue!
VWguru has highlighted the very issue in his posts, is it acceptable to use more fuel ( potentially more pollution) to dupe the results in a particular way as to not fix the original problem the particular limit was introduced to resolve ?
I apologise to any tree huggers which may have been offended by my post, however simply duping the results is purely smoke and mirrors, ( excuse the pun) the real problem still exists and will continue to exist until a practical / real choice exists for the mass consumer.
We are in a transition period which needs to be filled by technology, not BS, and until such time as the perfect solution is available we will be subject to the corporate and political push me pull you resulting in real world BS
 
If VW haven't got the Euro6 emission system functioning in what should be a seemless manner there isn't much hope for the 2020 emission level being achieved. Cali Grand the answer?
 
Amarillo said:
I think the idea of climate change has moved beyond the tree hugging minority into mainstream belief.

The problem is solvable, just as a worldwide commitment solved the hole in the ozone layer with the Montreal Protocol.

Follow my blog: www.au-revoir.eu
Click to expand...

Solvable if we can work out how to stop volcanoes erupting & the like.

The climate on earth was changing long before the combustion engine was invented.

Of the stuff we can change...

The 15 largest cargo ships currently in operation spew out more emissions than all the cars on the planet, to me it would make more sense to target them rather than motorists.

There are far more emissions created by building a new car compared with those that will ever be emitted by a car that is already in use.
Buy your nice "clean in use" japanese electric car but please factor in the emissions from the ship used to get it here.
 
andyinluton said:
The 15 largest cargo ships currently in operation spew out more emissions than all the cars on the planet, to me it would make more sense to target them rather than motorists.
Click to expand...
The 15 biggest ships produce more sulfur oxide pollutants than all the cars in the world, because they run on completely different fuels. A ship produces more carbon dioxide emission per mile and per gallon of fuel than a car. Ships in general, however, have the lowest emission levels of any other method of cargo transport , producing fewer emissions per ton of freight per mile than barges, trains or trucks.
https://www.quora.com/Is-it-true-th...orld-produce-more-pollution-than-all-the-cars
There are far more emissions created by building a new car compared with those that will ever be emitted by a car that is already in use.
Click to expand...
Good article here.
https://www.theguardian.com/environment/green-living-blog/2010/sep/23/carbon-footprint-new-car
Buy your nice "clean in use" japanese electric car but please factor in the emissions from the ship used to get it here.
Click to expand...
From Sunderland?
 
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