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DPF Burn-off, Overrun and Instantaneous MPG


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8 minutes ago, JTQ said:

 

Typically with our domestic car's DPFs they tend to block with soot by 20% in something like  300 to 500 miles, and this figure triggers an active burn.

 

 

OK, but how do you know this?  Does your car give you a read out or what?  How do you know it's  doing an active burn?  I've  never noticed any change with mine.

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19 minutes ago, rovinmad said:

OK, but how do you know this?  Does your car give you a read out or what?  How do you know it's  doing an active burn?  I've  never noticed any change with mine.

 

I only know because I have tended to take an interest, as having a history involving diesel engine development; but the quality of info available to me these days is only as good as the answers I find, its no longer from "my" research.

 

The only way I know with my wife's Golf is into an active DPF burn, is its cooling fan runs.

With my Disco I have not a clue, but I know it must be working because its done 18K miles, no way would it be running if it had not. The Disco tows 50% of its use,. 

So with the Golf and a technical bent I am aware of regerenations, but with the Disco I am not.

I would like to know these things, but the domestic car market does not cater for anoraks, now its minimum, just vital info.

Then I only want to know really so I drive on a bit longer to complete the task rather than clock up yet another aborted attempt.

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16 minutes ago, JTQ said:

......With my Disco I have not a clue, but I know it must be working because its done 18K miles.....

 

I know when my D4 burn starts as the exhaust note noticably changes to a more gruff sound from inside the car, even my wife notices.

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Stay safe - Griff.  :ph34r:

Wheels at the front - Discovery 4. Wheels at the back - Bessacarr 845.

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8 minutes ago, Griff said:

 

I know when my D4 burn starts as the exhaust note noticably changes to a more gruff sound from inside the car, even my wife notices.

 

Thanks, I will have to drive with my hearing aids in, something I avoid typically, I prefer the quiet, less worrying.

 

Is yours an Adblue version, ours is, a run out model?  

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There are many permutations, both in how they are done and how well they are managed, not to mention whether the driver can tell whether they are being done.

In my case, FIAT engine in a Vauxhall, raw fuel is injected into the cylinder during the exhaust stroke. The only way that the driver knows it is happening is by the increased instant fuel consumption or fan run on.

It does it every 500miles or so whether it need it or not, or sometimes just for the hell of it (so it seems!).

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3 minutes ago, JTQ said:

 

Thanks, I will have to drive with my hearing aids in, something I avoid typically, I prefer the quiet, less worrying.

 

Is yours an Adblue version, ours is, a run out model?  

 

No not Adblue, a 2015 model.

Stay safe - Griff.  :ph34r:

Wheels at the front - Discovery 4. Wheels at the back - Bessacarr 845.

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1 hour ago, JTQ said:

I feel that saying 300 to 400 C  DPF entry temperature is" ample for passive regeneration" will for many of us with DPFs be somewhat misleading.

The 400 C [barely a hint of red in the dark] is just about on the very lowest threshold  at which  a passive burn might be obtained with the likes of some Citroen & Peugeot engines that specifically employ a fuel carried catalyst like cerium oxide, the active component of Eoyls. However, the temperature needed   even then with a fuel carried catalyst is  typically considered as 500 C.

 For those systems without the likes of Eoyls, then there needs to be an entry temperature of about 600C for a DPF burn passive or otherwise

 

An important function of fuel carrier catalyst like Eoyls is simply to reduce the  DPF burn temperature so the better chances of passive regeneration. These days it is not so commonly adopted in our cars, many simply rely on active regeneration where use of excess fuel provides the temperature lift. If your driving gets a passive burn that's a bonus, in reality, I doubt with our cars many do.

 

That occasional motorway thrash for most of us is not to get a passive burn more to get a full cycle active burn,  things up hot enough for the ECU to initiate it and long enough to complete it.

 

 

Passive Regeneration, as the name implies, does not require additional energy to carry out the regeneration process.  Instead, this strategy relies on the oxidation of soot in the presence of NO2, which can occur at much lower temperatures in the range of 250 °C to 400 °C (480 °F to 750 °F).  A catalyst is used to convert NO present in the exhaust to NO2.  These catalysts require the use of precious metals to facilitate the reaction, platinum (Pt), in particular, which adds additional cost to the system.  In some cases the catalyst coating is applied directly to the DPF, as with a catalyzed DPF (C-DPF), or an upstream oxidation catalyst (DOC) may also be used.

 

Active Regeneration requires the addition of heat to the exhaust to increase the temperature of the soot to the point at which it will oxidize in the presence of excess oxygen in the exhaust.  The combustion of soot in oxygen typically requires temperatures above 550 °C (1,000 °F).  Since these high temperatures generally do not occur during normal engine operation, a number of strategies are used to actively increase the exhaust temperature

 

Active regeneration systems may include the use of a diesel burner to directly heat the exhaust entering the DPF or the use of a diesel oxidation catalyst (DOC) to oxidize diesel fuel over the catalyst as a means for increasing the DPF temperature.  Use of the DOC also requires excess diesel fuel in the exhaust, which may be accomplished through a fuel injector (hydrocarbon doser) mounted in the exhaust upstream of the DOC, or through late in-cylinder post injection strategies.  Other forms of active regeneration include the use of electrical heating elements, microwaves, or plasma burners.

 

As I mentioned earlier, there are many systems and combinations of systems in use, it isn't a one hat fits all, all attain the same end, the Eolys and Fords PAT additive help the process by allowing the carbon particles to be oxidised at lower temperatures in oxygen rich exhaust gasses, i.e. their systems don't support the NO2 system.

 

What is often forgotten is that the residue from burning soot is ash, which stays in the DPF, can partially block it  and increase back pressure in the DPF, but not enough to promote an active re-gen, after a relatively short distance and time, in comparison with normal active re-gen, a little extra soot promotes an active re-gen and so it goes on, rinse and repeat, with the driver wondering whyh is fuel consumption is up and his fan is runningmore than it should.

Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it.  :rolleyes:

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We never notice it in our Santa Fe, it has only done 29000 miles in 4 years but is mainly used to tow now so gets a good run regularly.

My previous Saab used to smell hot when you switched off if it had done a regen. It had the FIAT derived 16v diesel that Vauxhall use too. It did go into safe mode once, the egr valve stuck and regen failed.

Dealer fitted new valve and did a regen all fine, it did get a good blast regularly!

 

Hyundai Santa Fe+Bailey Unicorn Cadiz

Mini Cooper convertible -fun Car!:)

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14 hours ago, Jaydug said:

 

There is!   And it's been used on some Citroen & Peugeot engines since 2000 and on every PSA engine since 2009.   On every Citroen or Peugeot, alongside the diesel tank there's a 3ltr tank (sometimes a bag) of PAT fluid.   Every time the car is refueled, a measured amount is injected into the diesel.   (So don't fill with small quantities)   Roughly a litre of Eolys will be used every 25000 miles, so warning messages will appear when the engine has covered 70-75K miles.   The tank then must be topped up with fluid and the computer told that it's been done.   The message warns of filter blockage.   Ignore the message and the engine goes to limp-mode.   The particle filter is fitted with a sensor at each end and when the computer detects a preset difference between the two, regeneration takes place.   It happens every 600 or so miles.        A year ago, at 70000 miles, the Eolys tank on my C5 was refilled in preparation before going to Spain.   

Eolys or Pat fluid shouldn't be confused with Adblue.    That is an additional fluid that has been used for the past few years.    PSA vehicles now require both.

I don't doubt that your car has these items, but having now checked again elsewhere, the 2013 Citroen C3 Picasso 1.6ltr diesel I have does not require it. It uses passive regeneration.

Hence the dealer telling me I need to do a decent run periodically, in order to burn off the particles.

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2 hours ago, Griff said:

 

I know when my D4 burn starts as the exhaust note noticably changes to a more gruff sound from inside the car, even my wife notices.

 

Cx-5 did that.

Tiguan I only know when the fan is running after stopping.

 

Xtrail I never noticed a regen taking place.

 

Courtesy of David Bodily Volkswagen Technical Support Spvecialist 

Diesel Particulate Filter (DPF) 

Detailed below is important information outlining the function and features of the Diesel Particulate filter which all members of your team need to be aware of. 

Diesel particulate filters are becoming more commonplace on diesel engines, particularly sizes 2.0L upwards. This is in order to reduce the exhaust emissions as required by European legislation. 

The prime reason for a DPF is to reduce particulate matter entering the atmosphere. Particulate matter is found in the form of soot, which is produced during diesel combustion. The DPF traps most of the soot which would normally travel down the 
exhaust and into the atmosphere. The DPF can hold a certain amount of soot, but not a huge quantity and therefore it needs to go through a process called ‘regeneration’ in order to clear the soot loading. When the soot goes through a ‘regeneration’ process it will be converted to a much smaller amount of ash. The ash is non-removable. There are two types of ‘regeneration’, passive and active. 

During long motorway journeys, passive regeneration will occur. This needs no intervention from the engine control unit. Due to the raised exhaust temperatures on a long journey (temperatures between 350 and 500°C), the procedure occurs slowly and continuously across the catalytic-coated (with platinum) DPF. The catalytic-coated DPF is situated close to the Engine, therefore the exhaust gas temperature is high enough (500°C) to ignite the soot particles. Due to this soot is burned-off and is converted into a smaller amount of ash. 

Active ‘regeneration’ is when the ECU intervenes when the soot loading in the DPF is calculated to be 45%. The procedure lasts for about 5 – 10 minutes. Specific measures are taken by the ECU to raise the engine exhaust temperature to above 600°C, these include switching off the exhaust gas recirculation and increasing the fuel injection period to include a small injection after the main injection. The soot particles are oxidised at this temperature. 

The ECU will trigger a regeneration process, if for some reason this is aborted, ie. customer slows down, stops etc, the process will be resumed when regeneration conditions are once again met, above 60km/h (38mph). This will continue for 15 minutes. 

If after 2 attempts of 15 minutes, a successful regeneration has not been possible, the loading will increase. At 50% soot loading, the ECU will continue to maintain maximum exhaust temperatures of 600°C to 650°C to cause a regeneration process. The system will try to run a regeneration process for 15 minutes. If unsuccessful, the system will repeat this process for a further 15 minutes, if still unsuccessful, the DPF light on the driver display panel will then be lit. 

The owners handbook states, the DPF symbol lights up to indicate that the diesel particulate filter has become obstructed with soot due to frequent short trips. When the warning lamp comes on, the driver should drive at a constant speed of at least 60 km/h for about 10 minutes. As a result of the increase in temperature the soot in the filter will be burned off. If the DPF symbol does not go out, the driver should contact an authorised Volkswagen repairer and have the fault rectified. 

At 55% soot loading the DPF light is lit on driver display panel. At this point the customer should follow the advice in the handbook. If they ignore this information and continue driving the vehicle until the soot loading reaches 75% without successful regeneration, additional warning lamps will light up. At this point the customer will also be complaining of lack of power, etc. 

At 75%, regeneration is still possible with the use of the VAS tester. Only when the loading is above 95%, is it necessary to replace the DPF unit. 

Operating Status System Response 
45% DPF Load Level 1 
- Normal Regeneration 
50% DPF Load Level 2 
- Regeneration at maximum exhaust 
temperatures 
55% DPF Load DPF lamp 
Regeneration from 60 km/h 
onwards 
("See operating manual") 
75% DPF Load DPF, SYS and MI lamp 
Torque limitation, EGR 
deactivation, 
Regeneration via VAG tester only 
95% DPF Load Replace the DPF Unit 

The Warranty department has confirmed that if there is no fault on the vehicle and DPF regeneration has been unsuccessful due to the customers driving style and the 
customers failure to comply with the instructions in the handbook, DPF replacement will not be paid for by warranty. 

Common causes for complaint 

• Frequent short journeys – Regeneration conditions are not met. Not recommended for sale in the Channel Islands and inner city driving.


• Customers who continue to drive the vehicle with DPF light on – Continued driving with the DPF light on and without successful regeneration results in excessive soot loading of the DPF, to a point where it is above 95% loaded. At this point regeneration is not an option and replacement of the DPF is 
necessary. 

• Fault 18434 particle filter bank 1 malfunction – Common fault code. This does not only relate to the DPF itself, but the entire exhaust gas handling system. This can be caused by defective temperature sensors, pressure sensors, additive 
system components (if applicable), poor connections, wiring issues, etc. 

Important Information 

• Before diagnosing a problem vehicle or attempting to perform an emergency regeneration, it is important to obtain a full diagnostic log and read out relevant measured value blocks. These MVB’s contain important information on the condition of the DPF system and are essential in diagnosing the fault. When the DPF light is illuminated, it does not necessarily mean that the DPF requires regeneration. For further advice, please contact Technical Support with the information from the diagnostic log and MVB data. 

• If a problem vehicle arrives with the DPF light, the engine management light and the emissions light on. If during your diagnosis and reading of relevant MVB’s, you find that the soot loading exceeds 75% (but is still below 95%), an emergency regeneration procedure must be performed with the VAS tester. Further to this, the customer needs to be educated. They need to understand why the lights have appeared on the dash panel. Their attention needs to be brought to the owners handbook instructions, so that they are aware of what the DPF light means and what to do when it appears. This should prevent unnecessary repeat visits for regeneration purposes. 
David Bodily 

Volkswagen Technical Support Specialist
 

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16 hours ago, Fireman Iain said:

My Jeep brings a message up on the dash when it's doing an active regen. I've only ever seen it once, just after I collected it from the dealers, where presumably it had done a number of short trips. 

 

Never seen it since, so my driving style and journeys are obviously enough for regular passive regens. Mixed use, in winter I use it for the 7 mile round trip to the gym, 12 miles each way to work, and longer trips maybe only once a month or so. Summertime, I mostly use the motorbike, so the Jeep rarely does the short trips, mostly being used for towing and longer journeys. 

The lights to tell you of a regeneration taking place are usually your last warning to allow it to complete the process before you start getting knocked into limp mode. The process was more than likely disturbed (engine turned off) a few times previous

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For those who are interested in knowing how full there dpf is or regen etc. I have an app on android phone along with a cheap bluetooth adapter which can tell me how full or through a regeneration plus exhaust temps my car is (Astra). Its interesting to know but  not ideal as the app has to be on to tell me the details I want to know.

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2 hours ago, daveat92 said:

I don't doubt that your car has these items, but having now checked again elsewhere, the 2013 Citroen C3 Picasso 1.6ltr diesel I have does not require it. It uses passive regeneration.

Hence the dealer telling me I need to do a decent run periodically, in order to burn off the particles.

 

That's OK!  You believe what you wish however, take a look at this  video.   The guy is talking about his Peugeot 3008 which apart from the body shell, the running gear, engine and gearbox are the same as your car.      Here's another one - same engine as yours.

 

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Citroen C5-X7 Tourer+Avondale Rialto 480/2
https://jondogoescaravanning.com

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3 minutes ago, Edde said:

For those who are interested in knowing how full there dpf is or regen etc. I have an app on android phone along with a cheap bluetooth adapter which can tell me how full or through a regeneration plus exhaust temps my car is (Astra). Its interesting to know but  not ideal as the app has to be on to tell me the details I want to know.

 

I’m just happy to let the onboard computer system do it all for me. The designers of these systems, as well as auto gearboxes, climate control, self dipping headlights etc  are far cleverer than I will ever be. 

Experience is an awful teacher who ends up sending you simply horrifying bills

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In all VAG group cars it is easy to identify a regen.

 

Revs tend to sit around 1,000rpm at idle instead of 800rpm

 

Start/Stop function does not happen

 

Cooling fans stay on after engine switch off

 

Very warm around the middle of the car between front and rear passenger doors outside.

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