DPF - All

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Mon 15 Oct 2018 16:09
DPF - All - barney100

Seems like I'm in the DPF conundrum. I have a 2.1 diesel and do about 7,000 a year. I've had it four years now and wasn't aware 'til later about the problems. What's the best way to avoid the DPF issues?

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Mon 15 Oct 2018 16:12
DPF - All - Avant

But are your 7,000 miles made up of lots of short trips (in which case a petrol is far more suitable) or fewer, longer trips (in which case your diesel is fine)?

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Mon 15 Oct 2018 20:41
DPF - All - barney100

I take it down the motorway most weeks for 20 miles or so with a few short trips.when it warms up I put it in sport mode.

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Mon 15 Oct 2018 16:28
DPF - All - craig-pd130

The best thing to do is learn to recognise when a regeneration is happening (slightly 'boomy' engine note, slight loss of throttle response, etc) and don't switch the engine off until it's complete.

With most cars, it's not possible to trigger an active regeneration: these will happen as and when the car's ECU decides, based on the level of soot in the DPF, engine temp, driving conditions etc. A long journey at decent speed (note: NOT high rpm) will passively burn off soot but some cars do active regenerations on a mileage / time basis too.

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Mon 15 Oct 2018 16:46
DPF - All - ElHombre

I discovered, thanks to an owners forum, that when mine regenerates it also activates the heated rear window. Apparently this is to increase the load on the engine to assist with the regeneration although it doesn't illuminate the HRW switch.

I've installed a small LED in the tailgate trim wired into the HRW circuit, visible in the rear view mirror. This allows me to see when a regen is taking place so that I can continue driving until it is complete also allows me to monitor the frequency with which they occur.

Might be worth finding out if this, or a similar mod, can be done to yours.

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Mon 15 Oct 2018 17:10
DPF - All - gordonbennet

I've installed a small LED in the tailgate trim wired into the HRW circuit, visible in the rear view mirror. This allows me to see when a regen is taking place so that I can continue driving until it is complete also allows me to monitor the frequency with which they occur.

An excellent home made or aftermarket solution well done, but really it should not have been needed, the maker should have had suitable options on the menu so more informed (interested and/or sensible) owners could not only be informed a regen is taking place or imminent, but, as in some lorries, when conditions are suitable a regen could be driver triggered when convenient because the volume of the DPF itself is available.

The first car maker that comes up with this will have a clear (no pun intended) advantage.

Edited by gordonbennet on 15/10/2018 at 17:10

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Tue 16 Oct 2018 13:38
DPF - All - Gibbo_Wirral

I discovered, thanks to an owners forum, that when mine regenerates it also activates the heated rear window. Apparently this is to increase the load on the engine to assist with the regeneration although it doesn't illuminate the HRW switch.

If yours has heated door mirrors, check them too. If it does activate them there's a really simple LED mod you can wire in to show regeneration.

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Tue 16 Oct 2018 17:40
DPF - All - craig-pd130

I discovered, thanks to an owners forum, that when mine regenerates it also activates the heated rear window. Apparently this is to increase the load on the engine to assist with the regeneration although it doesn't illuminate the HRW switch.

Good point, my 2008 Mondeo IV used to do this, although in the Mondeo's case the light on the HRW switch would come on.

On my most recent Volvo V60, start/stop was disabled while a regen was happening.

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Mon 15 Oct 2018 16:51
DPF - All - skidpan

With most cars, it's not possible to trigger an active regeneration: these will happen as and when the car's ECU decides, based on the level of soot in the DPF, engine temp, driving conditions etc. A long journey at decent speed (note: NOT high rpm) will passively burn off soot but some cars do active regenerations on a mileage / time basis too.

Exactly my experience. As an example the Kia took longer to complete a regen at 70 mph on the motorway (2200 rpm) than it did at 60 mph (1900 rpm). The manual said that regens were best between 1600 and 2000 rpm and this proves that the manufacturer knows more about his cars than a load of bar room experts who still dream about the Italian Tune Up from the 60's.

It did a regen every 250 miles regardless of the use it had been having. Drive for a couple of weeks in town, a regen every 250 miles. Drive to Scotland, 430 mile trip, it would do one or two regens depending on when the first was due.

Read the manual, there will be info in there that helps. Don't ask the dealer, he will have no idea. In the case of the Kia people on the forum had no idea whatsoever, one used to pay his local indy £250 to remove it and clean it out every year.

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Mon 15 Oct 2018 17:19
DPF - All - skidpan

I've installed a small LED in the tailgate trim wired into the HRW circuit, visible in the rear view mirror. This allows me to see when a regen is taking place so that I can continue driving until it is complete also allows me to monitor the frequency with which they occur.

On some makes the cooling fan runs permanently whilst a regen is taking place thus it should be possible to wire in a warning for that.

But beware, any changes or additions to the wiring that are not carried out by a dealer would probably cause warranty issues should the mod be deemed to have caused/contributed to the issue.

If its out of warranty no worries.

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Tue 16 Oct 2018 10:24
DPF - All - skidpan

I take it down the motorway most weeks for 20 miles or so

If that is simply to give the car a run rather than a necessary journey you are simply burning money. Buying a petrol and only doing the necessary mileage will cost less than buying a diesel and doing journeys specifically to keep the DPF healthy

with a few short trips.when it warms up I put it in sport mode.

Read what I and other have written above. Sport mode generally means more revs and more revs does not mean a better regen. In fact high revs will prevent a regen, the higher speed of the exhaust gasses can prevent the DPF heating to 600 degrees, that is why Kia and others specify the best revs to use, in Kias case 1600 to 2000.

RTFM and find the DPF section, there will be info instead of urban myth.

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Tue 16 Oct 2018 10:37
DPF - All - RT
RTFM and find the DPF section, there will be info instead of urban myth.

Many manuals have no information at all on DPF or regeneration

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Tue 16 Oct 2018 11:01
DPF - All - skidpan
RTFM and find the DPF section, there will be info instead of urban myth.

Many manuals have no information at all on DPF or regeneration

We had the BMW and Kia with DPF's and the manuals both included DPF info.

The Nissan,Seat and Skodas that we have bought after selling both diesels have all had DPF info sections in the manual.

The section in the manual for the Fabia has quite a bit of useful info about the DPF.

Couple of sections

To clean the filter, and where traffic conditions permit drive as follows for at least 15 minutes or until the indicator light goes out.

4th or 5th gear engaged (automatic transmission: position D / S).

Vehicle speed at least 70 km/h.

Engine speed between 1,800-2,500 rpm.

This is very different from the Kia 1600 to 2000 rpm info and shows why you MUST read the manual.

We encourage you to avoid constant short journeys. This will improve the combustion process of the soot particles in the diesel particulate filter.

Obviously its a bit late for people to read this if they only do short trips but in fairness its in the brochure as well.

Problem is very few people read anything. They might look at the 0-60 time, they look at nice pictures, they are probably impressed if its got 18" wheels with virtually no tyres. But to expect them to learn about the important stuff is expecting far too much. And expecting sales people to give truthful advice is totally unrealistic, all they want is to sell the most expensive highest spec car which is usually a diesel.

Take my MIL (please). She voted for Brexit and still cannot understand why there are so many foreign people in town when she voted for them all to be sent home. Like many others she had no idea what she was voting for.

Most diesel users have no idea that a DPF is fitted to their cars. Drivers of newer cars probably never have an issue, that is the area where used diesels have the majority of issues. And those buyers of older cheap diesels expecting cheap motoring find its a myth.

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Tue 16 Oct 2018 17:47
DPF - All - craig-pd130

Exactly my experience. As an example the Kia took longer to complete a regen at 70 mph on the motorway (2200 rpm) than it did at 60 mph (1900 rpm). The manual said that regens were best between 1600 and 2000 rpm and this proves that the manufacturer knows more about his cars than a load of bar room experts who still dream about the Italian Tune Up from the 60's.

Yes, the optimum rpm for active regeneration seems to be around the lower end of peak torque rpm range, which is in the 1,600 to 2,000rpm region for many turbodiesels.

At those rpm the BMEP is near its peak but gas flow isn't excessive. Also most cars throttle the inlet to the manifold using the anti-shudder flap to raise EGTs when the regen is happening, so if you give it a bootful the ECU can actually suspend the regeneration process.

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Tue 16 Oct 2018 19:58
DPF - All - barney100

I've looked at the manual and there is no mention of a DPF or indeed any light on the dashboard showing of regeneration. One poster stated his rear heated screen came on during regeneration, maybe that's why mine came on the other day.

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Sat 20 Oct 2018 21:56
DPF - All - daveyjp
I had the Forester serviced today and whilst picking up the car had a chat with the dealer service manager.

I mentioned Subaru dropping diesels and he was thankful of it. On a weekly basis he gets customers in with DPF and associated plumbing problems. In the vast majority of cases it is owners doing low miles who were seduced by the mpg figures. They have had decent mpg, but then get the bill for sorting out the DPF.

The impact of dieselgate and media stories about diesel, clean air zones etc means they now really struggle to get anyone interested in the few diesels they have in stock.

Being in the car trade he is hearing similar from dealers of marques which sell far far more cars a year than Subaru do.

He doesn't see diesel being chosen by many typical motorists over the next 2-3 years.
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