[Closed] Modern Diesel engines cars and their DPFs

A regular Italian tune up

Drive a petrol

If we are to believe the media, DPFs are the least of our worries. Either they'll ban diesels anywhere you might want to go or we'll run out of diesel.

I tell customers that's a DPF needs a "good" m/way run every 250 miles.
But it takes way longer to explain my definition of a good run isn't the same as theirs, I.e 2 junction on the daily rush hour commute in stop start traffic. Unfortunately DPF system isn't going anywhere and most diesels (euro 6) now have add blue as well. Modern diesels are great but extremely complex and cannot function with being ran at full running temperature. I would consider a petrol or moving further from work.

Maybe leave it in 5th instead of 6th?

From my reading of docs the regen cycle is triggered when then revs >2.5k (number fule system manufacture dependant) for a set period. So running in a lower gear from some time should trigger the regen cycle if you can keep the revs high for 15 min or so.

Stop driving like a total fanny!

Next time you have a clear slip road or stretch of road, get the revs up above 2000rpm and floor it!

Any ideas on whether its worth using the expensive Shell Vpower, BP Ultimate etc to reduce the risk of clogging of the EGR and/or DPF?

next one may well be petrol, as they're getting much more economical now, but I've only had this since January on a three year PCP deal

The roads on my run, while a nice scenic drive, aren't straight for long enough to get a good 2000rpm or more for a full 15-30 mins. Looks like I may need to take a decent motorway run somewhere once a week. Richmars, that may help too

I've been through this on another channel.

Essentially, "premium" fuel more because it contains more detergents that supermarket fuel; "Ultimate" and "Vpower" etc contain [i]cleaners[/i], and a minute extra power gain through added combustion. Normal premium has less "[i]cleaners[/i]" but more "[i]keep it clean[/i]" so yes its worth using BP / Shell normal vs supermarket fuel which is relatively dirty. Note that an already clean engine will not perform any better with normal premium fuel.

The advice above is correct. The DPF will either passively (by getting heated up during normal driving) or forcibly (the ECU forces fuel to be burned at high temps - known as a regen process) burn off soot to keep the DPF from being clogged. Most modern cars don't do this (esp. the forced region) until a certain few conditions have been met; The engine must be at optimum temp, the car is driving circa/over 2000 revs. This process normally takes about 10 minutes and in most modern cars is imperceptible. You [i]may[/i] feel a loss of power, reluctant accelerations, smell of burning if stationary, lower current MPG, or puff of dirty smoke during acceleration.

The most likely time for this to happen is on a typically motorway journey. Short stop start journeys do not meet the conditions and therefore you will be building up soot throughout the system. So to look after you engine spend a few extra pence on a branded fuel, and take it for a long journey to invoke the DPF regen. Your dealer can forcibly invoke the regen on the ramp via the ECU if necessary.

Get it deleted from the ECU and removed from the exhaust system.

^^^ Which is an MOT fail if they spot it through emissions or visuals.

so yes its worth using BP / Shell normal vs supermarket fuel which is relatively dirty.

It's all the same fuel the additives are gimmicks to charge you more.

Drive it with later gear changes and it'll be fine.

It's all the same fuel the additives are gimmicks to charge you more.

Possibly, but I'm still looking for a reason why my last diesel struggled (rough, smoky and cutting out) for the first cold 30 seconds or so each run when on supermarket stuff, but was absolutely fine on BP/Esso/etc

^ This for me too...my old Freelander was a different car on the good stuff, paid for itself as well with the extra mpg

It's all the same fuel the additives are gimmicks to charge you more

No it isn't, there's a reason its usually cheaper. Its the same base fuel yes, but it has no / less additives in than branded fuel. I'm not suggesting it lives up to the marketing hype, but it is better for your engine.

Ermmm! That's what I said.

Oh you added a bit. I notice no difference at all when I use it.

Shell nitro plus is the best of all the updated fuels. Never use supermarket fuels and no trying to drive like a 90 year old...3-.3500rpm tends to be max boost engine speed for turbos.....its fitted for efficiency and economy so use the turbo and drive it.....
Failing that flog it for a petrol engine variant if you like the car....way it's going diesels really going to go through the roof!

What I don't understand is that if the DPF is there to prevent particles getting into the atmosphere, but cleans itself by burning these particles off - out of the exhaust and into the atmosphere - what's the bloody point of them in the first place?

Flying ox - I think that by burning off through the DPF higher combustion temperatures (and therefore cleaner burn) can be achieved than in the engine (diesel engines not being that hot, relatively). That or all the nasties are got rid of on motorways and away from urban areas.

DPF problems made me get rid of my Trafic and change to a petrol car, miss my van 🙁

My van is rough as when it starts on tesco diesel, no problem on shell or BP. It's not the same.

Why don't the manufacturers include a caption / indicator light to show when the regen is taking place?

Or at the very least a warning when the time since the last regen is becoming excessive?

Or a means of guiding the driver to achieve a regen when driving e.g. hit X revs?

Cars have so many other warnings / guidance (like change gear now, too hot, low oil etc) why not have some for the DPF?

Without information, how are drivers meant to influence something they can't see?

The manufacturers need to do more to help.

Rant over.

^^^^ Some manufacturers vehicles have stickers or dangly things on mirrors in the car with just that when they are fresh off the transporter or at least a look in the handbook reference.

I suspect many get chucked away before the consumer sees them.

I guess the regen process doesn't necessarily occur every journey, it allows the DPF to accumulate soot and then kicks in. So drivers have no idea how often the light should come on, if it should come on every journey or if it needs to come on at all. The point is to have a system that works that is invisible to the driver. Too much risk to confuse rather than to comfort.

But it seems to me that the imperceptible approach isn't working. It's costing people money because they can't tell whether they've had a regen or not. There needs to be something 'active', like the service interval warning or airbag failure light, to get the owners to take action.

The Flying Ox - Member
What I don't understand is that if the DPF is there to prevent particles getting into the atmosphere, but cleans itself by burning these particles off - out of the exhaust and into the atmosphere - what's the bloody point of them in the first place?
POSTED 40 MINUTES AGO # REPORT-POST

It works in a similar way to a catalytic converter, once it gets up to temp it can burn these particulates so you don't get the soot - but unlike a cat that just lets the gases through until it's warm it get clogged by them. It really doesn't take much to clear them normally and most cars not have s re-gen map built into the ECU which can make the car run warmer to clear them. They do indeed get clogged if diesels don't get a nice warm long run now and again - but of course every dealer in the UK no had thier default excuse should anyone ever ask for some warranty work on them.

My understanding is that give it 'the beans' now and again isn't nearly as effective as 20 mins at 70 when the car is fully up to temp.

I've got a diesel for company car tax reasons, I only drive 3 miles to work so it should be ****ed, but my weekly drive to my riding spot down the M-Way means in 40k miles it's been absolutey fine.

Oh and it runs on that oh so 'dirty' super market diesel - none of that snake oil stuff for me.

DPFs typically regen every 300 to 600km going by any I've dealt with lately. Some vehicles you'll never notice, some will hesitate a bit while it's happening. Most modern DPFs will quite happily regen at not much above idle speed, provided all the required conditions have been met.

Flying Ox, the DPF is basically a ceramic filter, so particles above the filter size never get through it. During a regen the temperature of the ceramic is raised so the built up particles burn of into smaller particles, which can pass through the filter.

to get the owners to take action.

You'll just have a big queue of people going to their garage to complain that a light's come on

Buy a diesel Honda as they don't have, or indeed need, a DPF...

Or buy a petrol car.

Or just use your bike 🙂

Or have an old diesel pre DPF...

Although the baby robins don't like them

Get it deleted from the ECU and removed from the exhaust system.

Which is the path I chose and I've never looked back.

Buy a diesel Honda as they don't have, or indeed need, a DPF...

And who told you that?
I can assure you Honda diesels have DPFs, as out of the company cars we deal with, Honda DPFs have given us the biggest problems.

Why don't Honda diesels have or need PDFs?

Different cars have different conditions for the auto regen, worth checking. On my bmw the fuel tank has to be more than half full for the regen to be triggered.

I think that by burning off through the DPF higher combustion temperatures (and therefore cleaner burn) can be achieved than in the engine (diesel engines not being that hot, relatively).

Right and wrong.

Yes, higher temperatures are achieved in the DPF to burn off the soot but this is only as a consequence of the artificially lowered combustion temperature (thank you EGR) in order to lower NOX emissions.

Diesels do run cooler but older diesels were much hotter and consequently generated less soot (in theory).

First gen Honda diesel's didn't have DPF's. Not sure about the new ones.

Why don't Honda diesels have or need PDFs?

They're not Acrobatic?

[i]They're not Acrobatic? [/i]

Badum-tish 🙂

But it seems to me that the imperceptible approach isn't working. It's costing people money because they can't tell whether they've had a regen or not. There needs to be something 'active', like the service interval warning or airbag failure light, to get the owners to take action.

Say what? If you knew it was happening with a light to tell you, the car would go through exactly the same motions and nothing would change. Possibly in your head you'd tame your driving style in an effort to save fuel, but this - for example tendling around at 1500 reves in 6th gear) won't help the process and will perhaps just lead to the next regen happening slightly earlier.

My Honda doesn't have a DPF but in the Halfords oil flipcard thing there is a listing for a DPF model with a different oil...a low soot variant to avoid clogging the DPF.

And this is where some of the issue stems from...who services your car, and are they using the correct oil, or have they just got a big drum of 5w30 that does the job whether it be a 10 year old Transit, a 5yr old Petrol city car, or a 3yr old modern diesel with DPF?

My dad's Fiat had constant problems and needed yearly forced regens...I'm convinced it's due to going to a cheap backstreet garage. They didn't even know how to reset the flashing oil light (service indicator), Google knows it's just a sequence of button presses to reset without a computer.

From what I've been told (& my recent experience with a 1.2 petrol Seat Leon) the modern petrol engines have exactly the same issues.

But it seems to me that the imperceptible approach isn't working. It's costing people money because they can't tell whether they've had a regen or not. There needs to be something 'active', like the service interval warning or airbag failure light, to get the owners to take action.

I'd like a light to say the dpf regen is due in x number of miles, and then the option to self-initiate it within that period. My drives are a mix of short local trips and longer ones on duel carriageways etc, yet the regen invariably starts when I'm nearing home, requiring another wasteful 15minute drive.

Kryton, look at it the other way. If you've not seen a light, then maybe you'd razz it to initiatiate a regen and save yourself the cost of fixing a knackered DPF?

A light comes to tell me to top up the windscreen wash but not to 'clean' the DPF. It's crazy.

On my Kuga there's a light at the top of the instrument cluster that occasionally blinks furiously for about 2 minutes. Nothing in the manual and the Kuga forums don't know what it is.

Perhaps it's morse code for "you need to do something about your DPF now"

My golf has a DPF and if i've not been on the motorway for a bit it does regen itself and keeps the fans running when I turn the car off because it's heated itself up for the regen.

Not had an issue in the 2.5 years I've had the car and thats nearly 60'000 miles now. Wouldn't fancy owning it after the warranty period though if the DPF goes and needs replacing.

I jumped into a vw caddy at work the other day. There's a sticker in the top corner of the windscreen saying that occasionally a 'regen' light will come on and to ignore it and continue driving.

I'm hoping that my new automatic 3l diesel engine sorts itself out as without cruising at 95mph, you can't actually maintain 2000rpm. It just changes upto 8th at about 55 and bumbles along at 1200rpm using the torque to shift it. Non selective automatic as well so nothing you can do.

Another dpf delete advocate of a professional reprogramme and removal. That £800 cost would have easily covered it.

Switch it off through software, knock the insides out of the filter and replace on the car.

Its less restrictive, uses less fuel
Doesn't regen where it puts more fuel in to burn residues, uses less fuel
Won't need a special trip on the motorway for 20 mins to clean it up
Won't block and cost loads to replace

Deliberately buying an older non dpf car has its upsides.

cost loads to replace

...when you fail your MoT. Don't have it removed; it's there for a reason.

MOT is a visual inspection only Rio....nothing is taken apart...

I reasoned it was causing more problems, so it had to go.

At some point, MOT testing will catch up with technology, and scanning the car for faults will be required, but VOSA isn't exactly quick to introduce new things, so it'll be a good few years yet.

On Euro 5 and above lorries/buses, all emission related fault codes have to be stored for over a year, even after being cleared. They also track and log lots of other variables, so it only takes a matter of minutes to find out if anything has been tampered with, or if there's any on going problems.
I'd imagine something similar will be in cars before long, as enforcement of emission standards is pretty high on the EU's hit list.

A DPF is only one part of the complexities of a modern diesel engine, and in the grand scheme of things, is pretty reliable. Early ones did have a few issues, which quite often a software update would help, but it's now a reasonably mature technology. Provided you're not continually doddering around town only doing a couple miles a time, the engine management does a pretty good job of keeping them clean without you ever realising.

I've got to deal with far more other issues than anything DPF specific. I don't think I've replaced any DPFs this year, but I've done several additional fuel injectors/glowplugs on Transits for the DPF regen, a couple EGR valves on Transporters, a Caddy marked beyond economical repair for the turbo actuator failing, a couple injectors on 1.7cdti Astras, along with seemingly endless blocked fuel filters.
The fleet of Merc Sprinters seem to of gotten past all the boost pressure leak problems from last year, although had to do one turbo and a full set of injectors recently, but that's a fleet with the average mileage now reaching 200k, with some reaching 600k.

So MC if you were buying a new (ish) car would you buy a diesel?

As above, MoT will soon catch up through fault code scanning or a more stringent emissions test. Also worth noting that it's an offence to drive a vehicle with the DPF removed.

Rio - Member
As above, MoT will soon catch up through fault code scanning or a more stringent emissions test. Also worth noting that it's an offence to drive a vehicle with the DPF removed.

This is true - they are policing this and EGR blanking although I don't know the detail. If you remove your DPF or drill the core you could be in for a failed MOT and nasty financial bill to get your car back on the road.

So MC if you were buying a new (ish) car would you buy a diesel?

As long as I was still doing the mileage to justify it, but the economics of it are getting lower. However, I've got the benefit of being able to fix things myself, and not running the risk of being fleeced by a dealer should things go wrong.

I don't think there's any dealer within a couple miles radius of my work that hasn't been pulled up by their relevant manufacturer over questionable work they've tried to bill us for - any queries, we send them to our HQ, who send them across to the relevant manufacturer, which usually results in a phone call direct from the manufacturer asking for details, as they won't risk losing national contracts because of poor dealers.

Personally, I can see why leasing is becoming so popular. You pay a fixed amount, and if it breaks, it's not your problem, and you don't run the risk of garages trying to sell you something you don't need.

Listening to R4 this morning the world is finally catching up with the environmental problems of diesel cars. How they ever became known as 'environmentally friendly' is one of the biggest cons of our time. The problem now is that air quality in big towns and cities has become a significant cause of death largely attributed to the rise of diesel powered cars - not the only cause of polution, but a significant one.

jimjam - Member

So MC if you were buying a new (ish) car would you buy a diesel?

I'm getting a sort of divide by zero error at the idea of MC buying a new car tbh.

Anything current-ish from the Honda diesel line up has a DPF. Over on the Honda forums there are a lot of people with DPF issues (although that's probably true for many marques). However there is remarkably little chat over on the Mercedes forum about DPF. Make of that what you want.

We have a petrol Honda that we use for running around locally and the Mercedes diesel gets used for longer runs. We've not had any DPF issues on this Mercedes or the previous one and I've probably put 120K onto the last two cars.

I'm getting a sort of divide by zero error at the idea of MC buying a new car tbh.

🙂

What I don't understand is that if the DPF is there to prevent particles getting into the atmosphere, but cleans itself by burning these particles off - out of the exhaust and into the atmosphere - what's the bloody point of them in the first place?

The particles are soot, ie carbon. The filter traps them, and (when it's time for regen) coupled with a catalyst in the filter the excess heat of regen oxidises the carbon into CO2 which is of course gaseous. It's a tiny amount of CO2 to the amount you'll be producing from your engine. So the particles are no more.

I'd like to know who's switched from typical diesel to say, a VAG TFSI engine, and how MPG compares between the two with the same driver and driving patterns.

I'm getting a sort of divide by zero error at the idea of MC buying a new car tbh.

The car is currently in bits, so the pre-abused combo is now on the road.

So from what I have read diesel is very dirty and we can expect massive price hikes due to increased demand and a limited supply chain as refineries have been closed and we rely more on fuel from Russia etc.

So for the driver who bought a diesel thinking it was kind to the environment and encouraged to buy it but the idiots in whitehall, it would seem he and 60% of his fellow drivers are doomed to pay more? IMO the idiots in power should do something about this after all they encouraged us to buy the bloody things!

Diesel is dead.
I love my old school mechanical 200tdi Landrover engine because of its simplicity, but I hate the TDCI in my Transit - it works okay but I always have a constant fear of something diesel related going expensively wrong.

But to be honest I would quite happily rip both engines of the vehicles and replace with a Tesla motor and battery pack if they were available second hand/used.
The transit is perfect for electricying.