This morning my friends toyota rav4(petrol) failed it's MOT on emissions.3 sensors I believe.She was quoted at least £700.The catalyst may be scrap as well£300. It's now gone to the local toyota agent for further evaluation,so £1000 just for starters........It's not just diesels with DPF problems. :no:

DPF may well reduce carbon particulates. My point is, under the Law of Unintended Consequences, what secondary damage are they causing in the process? Your first line sums it up - I made the clear choice: I cannot now use a diesel so I have a petrol. Instead of 12k miles per year at 51mpg I will drive 12k miles at 35mpg. In doing so I will burn around an extra 500 litres of fuel depleting a finite natural resource and generating around 1.25 tonnes of CO2. Is that worth the particulate reduction or is it the Law of Unintended Consequences in action?

What we should also remember is that the majority of the soot captured by the DPF is generated when the engine is cold and working less efficiently. The high motorway milers that suit the DPF generate less soot anyway.

I am not in disagreement with your thoughts on the beauracrazy. I have lived by supplying VOC control equipment to the auto industry till I retired earlier this week, so I am finally rid of the ignorant consultants and their sheenanigans.

My comment on the suitabilty of the diesel was based on basic facts, that diesels do not do well on short trips, DPF or not. I also don't feel that 12,000 miles a year, which is an average of 32 miles per day should be detrimental to getting and using a diesel engine - DPF or not.

My "normal" driving has been typically very short trips locally - 6 mile round trip with a stop in the middle pus some infrequent long stretches down through Europe. The 2.0 TDI has performed well under these conditions, but clearly likes a blow-out on the Bahn.

Finally, i do believe the majority of the soot comes during hard acceleration as well as in the initial cold start-up phase.

Edited 5 November, 201015 yr by Agerbundsen

...I have lived by supplying VOC control equipment to the auto industry till I retired earlier this week,..

My comment on the suitabilty of the diesel was based on basic facts, that diesels do not do well on short trips, DPF or not. I also don't feel that 12,000 miles a year, which is an average of 32 miles per day should be detrimental to getting and using a diesel engine - DPF or not.

The 12000 per year is not as uniform as that unfortuately.

Get out and about a lot in Spring-Summer-Autumn but during winter I do little more than my 8 mile each way commute 5 days a week The journey to work is mostly flat and downhill which meant that the 1.9TDi never got warm - it did regularly show 70+mpg on the computer though!

Interesting about the VOC control! We are just installing an RTO into a new process so VOC emissions regs are something I am getting to grips with at the moment.

Good luck for your retirement

+1 on the retirement ,welcome to the club. :yes:

+1 on the retirement ,welcome to the club. :yes:

Thanks, I will figure it out after a while.

Well here's how I see it, if you want a car to perform you fit a free flow exhaust, if you stick a potato up the exhaust you will at best cause the engine to cut out, at worst blow the engine completely, a DPF is a potato imo, a complete contradiction in term's for a car engine.

What it does?

It stores up soot, should the soot overwhelm it the soot then compacts and causes a blockage, if it's too badly blocked it either need's a pro regen using up more fuel and creating more soot, catch 22 eh.

Then if it dies completely you have to make another soot can to replace it with, more enviromently friendly action eh?

Add in the additive's, which are so safe and non toxic it has to be kept in a sealed dispenser, and cost a fortune to top up.

So we then have our 80% full tin can, we go out on the motorway and WHOOOOOOSH it get's blown out all over an area that has turbulent air surrounding it, dispensing the ash all over the place for the wildlife to enjoy.

Never have I ever seen something so enforced on a man by someone who knows nothing about nothing, i.e greenies and minister's, the people who drive 2CV6's and VW Combi's because they are eco friendly in their minds.

Now, until Hydrogen is freely available to use, there is nothing you can do to 100% stop byproduct's of fossil fuel's, so stop forcing the car maker's top adopt technologies that will only fail, best example is a Prius, looks like the best compromise to contain urban pollution, until you look at the footprint it left being made in the first place, like making a popsicle out of 10000 oranges.

Supurbia, I take it you don't like diesel particulate filters?

There is a little misconception you need to get corrected:

Combustion of diesel fuel does not generate any ash. If it did, the DPF would be completely impossible. The collected soot is burned to CO2, and the process also generates a little NOx, neither of which are solids, so no ash at all.

For those of you that don't visit the Octavia II forum often, here is an interesting thread on this very DPF issue and supermarket fuel:

http://briskoda.net/forums/topic/175768-the-dpf-and-supermarket-fuel/

The DPF used in the Yeti and Superb 2 need no additives added as they dont need the additive, only the Superb MK1 used an additive and that was because of the location of the DPF as it was added later in the cars life.

Both my diesel Freelanders had DPF's.

Both did nearly 100k miles with no problems at all. This included regular off-road excursions and dunkings in mud and water.

Agerbundsen. You are correct in that the combustion of diesel creates soot

My understanding however is that when the soot burns off there is a small amount of ash left as a by-product of the combustion as well as

the co2 and NOx

This is why DPFs don't last forever - the eventually get choked by ash even when treated correctly.

When my DPF was declared dead on the Merc diagnostics (It was on a Merc)

The report read 'Ash content too high - replace filter'

Agerbundsen. You are correct in that the combustion of diesel creates soot

My understanding however is that when the soot burns off there is a small amount of ash left as a by-product of the combustion as well as

the co2 and NOx

This is why DPFs don't last forever - the eventually get choked by ash even when treated correctly.

When my DPF was declared dead on the Merc diagnostics (It was on a Merc)

The report read 'Ash content too high - replace filter'

The ash was probably from the burnt engine oil, not the fuel

The ash was probably from the burnt engine oil, not the fuel

In addition the Diesel will also contain minute traces of inorganic matter - mainly silica and metals. Extremely tiny amounts but over time it will start to add up.

Edit: Just Googled for EN590 (the European standard for diesel fuel) and it seems that diesel can have an ash content of up to 0.01% by mass.

That means that every 55 litre tankful of diesel can produce up to 4.5grams of ash. Hopefully the typical values are well below the maximum!!!!

Edited 9 November, 201015 yr by eccleshill

Just seen an interesting post on DPF in the Fabia II forum My link see post #8

TP

Edited 16 November, 201015 yr by The Plumber

Just seen an interesting post on DPF in the Fabia II forum My link see post #8

TP

Very interesting and good to see the 'inside track' on the subject.

For what it is worth, I have been driving an Audi A5 with the 2.0L TDI CR 170 engine (same as used in Octavia, Yeti & Superb) for the last six week and 1500 miles. It is one of our company cars and I took it over from a guy who did an 8 mile each way commute in heavy NW London traffic and only occasional motorway runs. When I took it over it seemed sluggish and lethargic.

My daily commute is 25 miles each way with 18 miles on motorway and I will use full throttle/high revs for acceleration at least on a couple of occasions on each trip. I'm sure that this has lead to a progressive cleaning out of the DPF and I have noticed that the car has felt far more sprightly and responsive in the last week or so, the engine/exhaust sounding sweeter too.

As an ashamed Octavia owner might i ask where the DPF is located in the Yeti?

Cos I note that in the 1.6CR Octavia it is right next to the turbo & therefore as hot as poss.

(I would tend to unfortunately agree that it F--ks the fuel consumption though.)

As in i am only really getting the same mpg as i get out of a Galaxy ( a substantially larger heavier bluffer vehicle) fitted with the venerable 1.9TDI.

So No progress in real terms in 12 years.

Scheesh

Just had my dpf refilled at motorline Dartford an excellent service from the guys down there.

Many dealers have never done this sevice as the oil pump normaly packs up before it needs doing and therefore the car goes down the scrapper as skoda say its not a fault, funny hoe VW sold all there old engines to Skoda when they had all the same problems with there old Passats.

The usual service interval for complete change is 75K-85K dependent on your driving style and as it takes it signal from the doors the more you get in and out of the vehicle the more it regenerates itself.

Just had my dpf refilled at motorline Dartford an excellent service from the guys down there.

Many dealers have never done this sevice as the oil pump normaly packs up before it needs doing and therefore the car goes down the scrapper as skoda say its not a fault, funny hoe VW sold all there old engines to Skoda when they had all the same problems with there old Passats.

Ah; we have to remember that the Mk I Superb has a different DPF & regeneration system, with a tank of urea that gets squirted into the DPF (IIRC), to that used in the Superb II, Octavia II and Yeti where diesel fuel is injected into the DPF for the regeneration process.

Current cars do not therefore have any 'serviceable' item as part of the DPF system.

LOL

Ah; we have to remember that the Mk I Superb has a different DPF & regeneration system, with a tank of urea that gets squirted into the DPF (IIRC), to that used in the Superb II, Octavia II and Yeti where diesel fuel is injected into the DPF for the regeneration process.

Current cars do not therefore have any 'serviceable' item as part of the DPF system.

You are confusing two different exhaust treatment systems. A DPF is a diesel particulate filter and is little more than a physical filter to remove particles of soot and ash from the exhaust gases; it is usually a network of porous ceramic channels that the gases have to flow through and, in doing so, leae behind the particles larger than the pore size. After a while they obviously get blocked and need regenerating, which is achieved by raising the temperature within the DPF to burn off the soot. Note though that the ash particles created by burning engine oil are made not of carbon but of metal oxides (calcium, zinc, magnesium etc) and can not be burnt away. This is why you must use a 'low ash' oil with DPF-equipped cars and also why eventually they need cleaning or replacing. DPFs are used on engines that are tuned to run a bit cooler and thus create a lot of soot but low NOx levels.

The use of a urea solution (commonly known as AdBlue) is with a system called selective catalytic reduction (SCR). This is a chemical process that uses a catalyst and the injected urea to react with the NOx in the exhaust stream and turn it to N2 and water. This does not do anything for soot, but then SCR is usually used on engines that are tuned to run hotter and thus create high NOx levels but low soot levels. Lots of HGVs use SCR; you will often see a small AdBlue tank next to the fuel tank on Euro IV and Euro V trucks. It isn't used much in cars, although I understand MB and Mitsubishi have used it. The idea is that the urea will last between services and be topped up then.

The Yeti does not have an SCR but does have a DPF.

Just had my dpf refilled at motorline Dartford an excellent service from the guys down there.

Many dealers have never done this sevice as the oil pump normaly packs up before it needs doing and therefore the car goes down the scrapper as skoda say its not a fault, funny hoe VW sold all there old engines to Skoda when they had all the same problems with there old Passats.

Where is the article you read that states VW sold their engines to Skoda due to being crap......

Ignore his comment, especially as it does apply to any of the engines fitted to Yetis.