The DPF has a metalic CAT at the front to create the combustion heat and a ceramic core a the rear. Very common in these cases that excessive heat caused the metalic CAT part to melt and cause the blockage. 2012 TDV8 Vogue (L322)

Hi Andy, the garage you spoke to

"the garage said that they have worked on over 1500 DPFs since they started doing this as a specialism"

are they a different company to the DPF Clean Team in Milton Keynes ??

https://dpfcleanteam.co.uk/how-it-works.php

pcourtney - yes, I used a nearby garage that also specialises in DPFs as an additional service. They removed the DPF and it was sent to DPF Clean Team in MK for a machine flush. The garage wanted to try and clean on the vehicle, but there was no guarantee it would solve the problem However, after speaking with DPF Clean Team, it was a no-brainer to send the DPF to them as they offered the 'no fix no fee' promise. They also picked up my dpf and have returned it free of charge and as such, I would highly recommend them.

I'm not going to name the garage I'm using as yet as the job is not complete. Their diagnostic method seems utterly sound and they certainly know what they're doing. However, until I have the brand new DPF back on the vehicle and we can test it to ensure the whole system from air intake all the way through to exhaust is working as it should, I am going to reserve final judgement on them! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

It’s been 2 months since my last post so thought an update was due…

In short, I ended up having a new DPF fitted and all seems to be sound. I’ve since done a little over 1250miles, have had 3 demanded regens and all 3 have successfully completed. The soot accumulation rate is unbelievably low (when compared to before) and, because the intake side of the system was high-pressure tested for any leaks, I am confident that there’s no over-sooting taking place. If anything, I was worried that the demanded Regens weren’t taking place often enough as the WM says that Active Regens generally take place every 250 miles. It does say that this can vary depending on driving style, giving the example that city driving will initiate more frequent Active Regens. However, whilst the WM doesn’t mention the possibility of longer intervals, I have to assume that approx 400 miles between Active Regens is plausible if doing mainly motorway driving. My 1250 miles has been overwhelmingly motorway/extra-urban as lots of long drives since getting the car back. What I don’t know is whether the failsafe trigger is an arbitrary mileage (e.g. max 300 mil before demand if no other previous trigger), or whether it is always based on a combination of driving style, distance travelled and back pressure. Anyway, I digress…

So, the reason for the new DPF was that DPF Clean couldn’t get the back pressure below acceptable tolerance meaning that it was almost certain that the monolith was damaged. This was almost certainly caused by me doing forced regens using my GAP IID, so I urge all readers to take heed of my mistake! The rookie error I made was thinking that forcing a regen would clean my DPF when it was obviously blocked. What I should’ve done was get the DPF cleaned as soon as I got the red triangle and not driven the car at all until that had happened. However, you live and you learn!

The only thing we don’t know is what caused the DPF to block up in the first place. We have a number of theories but we will never know for certain. However, that facts are:
- Car was on over 100k mikes and had a number of DPF cleans under previous ownership. It was a London car so obviously being driven in the wrong environment.
- I had a new EGR fitted (under warranty) so we know the exhaust system was already gunked up with oily soot.
Therefore, the most plausible explanation is that the DPF was already partially damaged and there was enough soot in the system to create a blockage that couldn’t be fully cleared without chemicals. And then it just snowballed and I did nothing to help by forcing regens in the hope of clearing it without external assistance.

I’ve learned a huge amount regarding DPFs during this process and feel so much better informed and able to deal with any potential issue that may manifest in the future. I also learned that any DPF or EGR related fault codes will also prevent active Regens, so to keep an eagle eye out for them. I’ve been driving around with my GAP IID connected to read live values and been very happy seeing the soot values, back pressure voltage and exhaust temps all working perfectly, and will continue to monitor these going forward for peace of mind.

Finally, just a massive shout out to Jack at Millers Garage in Newbury. He’s been truly excellent looking after my vehicle throughout and I can’t recommend his approach and service highly enough. Whilst not a LR specialist, he deals with a lot of them and really knows his stuff. For DPF-related issues I would go back to him without question. Their labour rates are also incredibly reasonable at £80+VAT p/h. Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

Glad you got it sorted in the end and it's now behaving as it should. A new DPF will have lots's of soot capacity as it won't have any ash build-up so expect extended regen intervals. How much was a new DPF? 2012 TDV8 Vogue (L322)

Yes ash is usually the culprit especially on London cars etc where you cant give it a good blow.
I often during a AR keep the 2nd turbo active  2018 SE SDV8 4.4 Byron Blue

Ash can't be blown out by revving it any more than soot can  2012 TDV8 Vogue (L322)

Regeneration is the term used to describe cleaning of the DPF. During this process the ‘wet and sooty’ particulate matter is subjected to further combustion inside the DPF itself. Surface temperatures inside the DPF can exceed 600 Degrees Celsius, at which point the soot turns into a hot white ash. Some of this ash is blown out of the exhaust whilst some is retained inside the core of the DPF.


So engaging 2nd Turbo in my view has to assist in ash removal, it certainly wont do any harm  2018 SE SDV8 4.4 Byron Blue

deleted by author 2012 L322 4.4 TDV8 AB low mileage - a peach
1986 V8 Defender 90 County ex-Swiss Army - Red everything....

My preferred Independent: Roy Hardy. R & B AUTOS LTD, 20 Brook Road, Wimborne, Dorset, BH21 2BH (Ex LR Chief Technician)

Last edited by Range Rover L322 on 7th Jan 2023 6:26pm. Edited 2 times in total

I think is referring to 'booting it' after a regen has finished but even then the extra gasflow may just as easily lead to the ash becoming more compacted rather than being partially blown out under moderate gasflow. Additionally anyone who has not had the turbo drain mod done will be throwing oil through the DPF thus increasing the ash. 2012 TDV8 Vogue (L322)

Quote:

Kot your conclusion that the extra pressure from the second turbo might blow out ash is completely understandable and reasonable, however the DPF regen (often called a burn) is a chemical reaction not a result of, or improved by a pressure increase .

Turbo boost is controlled by the software during AR and EGR is closed, a kick wont do any harm

After all, very few of you will actually be aware an AR has started unless you monitor it live every trip (Skyscanner app), What do you think happens during this event (AR) and during normal driving, what happens every time you overtake? and give it a kick etc Get the mod done!

Quote:

the second turbo stops dumping fuel and stops the regen process (the fuel dump is the mechanism which starts the regen).

Sorry you are wrong!! The AR stops when it's finished or if you interrupt it and stop the car!!!.
Are you saying "If you make an overtake the AR stops!!! "

Extract from WSM-- When the supervisor function issues a regeneration request, the co-ordinator function requests EGR cut-off and a
regeneration specific turbocharger boost pressure control. It then waits for a feedback signal from the EGR system
confirming that the EGR valve is closed.
When the EGR valve is closed, the co-ordinator function initiates requests to increase engine load by controlling the
intake mass air flow.
Once confirmation is received that intake conditions are controlled or a calibration time has expired, the co-ordinator
function then changes to a state awaiting an accelerator pedal release manoeuvre from the driver. If this occurs or a
calibration time has expired, the co-ordinator function generates a request to control fuel injections to increase
exhaust gas temperature.

Quote:

you would like to see - run diagnostics and during a regen give it some welly. You will see the all the temps drop Bk 1 sns 1,2,3 and Bank 2 sensor 1. The one to watch is Bank 1 Sensor 2. at 37-60mph it will regen at 620-660ºC. If you boot it then you will lose temperature as it goes off regen.

It does what its designed to do during AR if you kick/overtake etc the system knows you have entered more fuel into the cycle, and temperatures will potentially increase, so to protect the components from over temperature, it controls fuel burn accordingly, of course there will be temperature deviations but this will be controlled by the software, but it doesn't stop the AR process.

DPF Fuel Management Function
The DPF fuel management function controls the following:
Timing and quantity of the four split injections per stroke (pilot, main and two post injections)
Injection pressure and the transition between the three different calibration levels of injection.
The fuel management calculates the quantity and timing for the four split injections, for each of the three calibration
levels for injection pressure, and also manages the transition between the levels.
The two post injections are required to separate the functionality of increasing in-cylinder gas temperatures and the
production of hydrocarbons. The first post injection is used to generate the higher in-cylinder gas temperature while
simultaneously retaining the same engine torque output produced during normal (non-regeneration) engine operation.
The second post injection is used to generate hydrocarbons by allowing unburnt fuel into the catalytic converter
without producing increased engine torque. 2018 SE SDV8 4.4 Byron Blue

The regen is very clever. Not sure why you find it so  2012 TDV8 Vogue (L322)

 2018 SE SDV8 4.4 Byron Blue

No matter what the Workshop manual says a regen will stop prematurely if you brake or accelerate hard when it's part way through at least on my L322 as I've observed it with the GAP IID tool. It then just waits until it fills up again and reaches it's soot limit rather than starting again to get the soot load down to minimum. 2012 TDV8 Vogue (L322)

deleted by author 2012 L322 4.4 TDV8 AB low mileage - a peach
1986 V8 Defender 90 County ex-Swiss Army - Red everything....

My preferred Independent: Roy Hardy. R & B AUTOS LTD, 20 Brook Road, Wimborne, Dorset, BH21 2BH (Ex LR Chief Technician)