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SCRF versus CSF - Are we on the bleeding edge?

77K views 153 replies 24 participants last post by  Rediscovery 
#1 ·
Up until 24th October 2017 the soot particulate filter had always been referred to on the forum as the "DPF". Then I received "the letter" from the Executive Board with this statement: "The SCRF (Selective catalytic reductant filter) component was inspected and soot was found on the rear face. This component contains the diesel particulate filter." Initially this statement made no sense to me, and subsequently I mis-identified the SCRF component as the DOC: https://www.discosportforums.co.uk/viewtopic.php?f=8&t=5379&p=76180&hilit=SCRF#p76180

Since then every time I have searched the web for "SCRF" at least one of the results has it written SCRF® implying that these devices contain protected intellectual copyright material. Trying to get to the bottom of this, today I found a scientific paper called "A Study of the Soot Combustion Efficiency of an SCRF® Catalyst vs a CSF During Active Regeneration" by Lasitha Cumaranatunge et al. The abstract immediately caught my attention:

The soot combustion efficiency of a Pt-based catalyzed soot filter (CSF) was compared to a Cu-SCR catalyst-coated soot filter (SCRF® catalyst) under active regeneration conditions. The CSF was found to have a significantly higher soot combustion efficiency compared to the SCRF® catalyst under typical active regeneration conditions (550-600 °C). Despite the thermodynamic equilibrium limitation of the NO oxidation reaction at high temperatures and the relatively small quantity of NOx in diesel exhaust compared to O2, there is sufficient NO2 production capacity in a CSF where the impact of NO2 to the overall soot combustion efficiency under active regeneration conditions is significant. The differences between a standard porosity filter typically used for a CSF vs a high-porosity filter used for an SCRF® catalyst can only account for a minor portion of the difference in the soot combustion efficiency observed between the CSF and SCRF® catalyst. The fast consumption of the NO2 produced in situ in the CSF by soot may be driving the thermodynamic equilibrium of the NO oxidation reaction to continuously produce more NO2 for further soot combustion during active regeneration, resulting in a significant increase in the soot combustion efficiency in a CSF compared to an SCRF® catalyst or an uncoated filter.

If the JLR component referred to in the letter actually does employ SCRF® technology, this opens up a new avenue of possibilities regarding the root cause for the unfathomably poor performance of the DPF and (with the glass decidedly half-full, to coin a phrase) maybe it points to the possibility of an early hardware fix. Any ideas?
 
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#127 ·
PhilMabbots17 said:
Hi JaneyB

You might need to contain your excitement for a bit longer. Since September 2015, when deliveries of Ingenium diesels began, JLR has:
1) delivered cars that concealed the problem from owners due to faulty "software";
2) denied the existence of the problem when it surfaced, allowing dealers to reset service counters and skip vital oil changes;
3) blamed the high oil dilution on a variety of factors, most of which boiled down to "software";
4) blamed "driving style" when they could no longer get away with blaming "software";
5) admitting in a leaked document that the problem is real and caused by the exhaust architecture and hardware;
6) admitted in the same document to changing marketing materials to deflect future customer dissatisfaction;
7) 37 months after the first faulty cars were delivered, acknowledged that there is a known problem which will be fixed by....wait for it...…
SOFTWARE !!! :lol:

CRC@LandRover said:

I can confirm that Land Rover are currently working on a software enhancement in regards to the concerns that have been raised.

Unfortunately at this time, we have not been provided with an update as to when this will be released.

Once I have received further information I will arrange for the details to be posted in this forum.

I apologise for any inconvenience that this may cause.

Thanks,
Becci
^^^^^^^^^^^^^This^^^^^^^^^^^^

The "software enhancement" referred to by Becci on 19th October 2018 turned out to be N289, which Dan then told us on 12th March 2019 was going to raise the estimated diesel dilution percentage from 6% to 10%. After four years of Arthur Daley ducking and diving JLR finally ignored the advice of its own engineering management (TSEM level) and raised diesel dilution by two thirds to fool customers that there isn't a dilution problem on the D180. Because of this deception I won't know now when the smegging oil needs changing. Please feel free to tell me how this represents an "enhancement", JLR people reading this. :(

Newbies! Before you unconsciously join the ranks of the diesel disaffected, go and read the following post on Epace forums. It contains a clear technical explanation for the Evoque/DS/EPace exhaust design fault that might make your life a misery if you live in a city, town or village.

https://www.epaceforums.co.uk/viewtopic.php?f=8&t=249&p=5186#p5186

Read JLRP001000. View attachment 5997

Then this: [IMG=https://www.discosportforums.co.uk/download/file.php?id=9522][/IMG]

So that was 2015 to 2019. But you are looking at 20MY. If, having read all of this, you think it might still be wise to present some concerns to your salesman and he says that its OK because everything has been fixed on the 2020 models.....

.....ask for some solid proof. Because I've looked into this (on my back) and saw no evidence that anything has changed on either the All new Evoque or facelifted DS.
 

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#128 ·
PaulCP said:
Trojan said:
With all due respect to the OP, the list should now read.

Since September 2015, when deliveries of Ingenium diesels began, JLR has:

1) delivered cars that concealed the problem from owners due to faulty "software";
2) denied the existence of the problem when it surfaced, allowing dealers to reset service counters and skip vital oil changes;
3) blamed the high oil dilution on a variety of factors, most of which boiled down to "software";
4) blamed "driving style" when they could no longer get away with blaming "software";
5) admitting in a leaked document that the problem is real and caused by the exhaust architecture and hardware;
6) admitted in the same document to changing marketing materials to deflect future customer dissatisfaction;
7) admitted in another document that, actually, the DS IS more heavily affected by Dilution and DPF blockage due to the longer distance from the engine to the DPF;
8) told dealers to advise certain customers to steer away from the diesel DS altogether to minimise their risk of experiencing oil dilution or a blocked DPF (these customers would apparently be OK if they bought an XE, according to JLR);
9) changed the dilution trigger from 6% to 10% to squeeze out 66% more miles between oil changes; and
10) termed this erosion of failure margins a "software enhancement". :lol: :lol: :lol:

I've paid to watch less entertaining circuses.

CRC@LandRover said:

I can confirm that Land Rover are currently working on a software enhancement in regards to the concerns that have been raised.

Unfortunately at this time, we have not been provided with an update as to when this will be released.

Once I have received further information I will arrange for the details to be posted in this forum.

I apologise for any inconvenience that this may cause.

Thanks,
Becci
Sums it up perfectly 👍

A decent car spoiled by corporate greed and corporate contempt for customers.
Or, maybe a stubborn ego made a costly blunder by thinking that car design can trample over engineering wisdom?

In late 2017 this forum and Daily Telegraph columnist HonestJohn had pieced together enough information from different sources to put forward a working hypothesis to explain the appalling, unprecedented diesel dilution. It turned out to be correct.

Immediately, the smell of sh!t looking for a place to settle wafted around the corridors at GEDC. Bang on cue, McGovern and Rogers met the press for interviews. They spoke in coded phrases but with the benefit of hindsight it's easy to understand what was going on. McGovern briefed Autocar in an article that appeared on 31st October 2017; Rogers' response appeared less than 2 weeks later in the Daily Telegraph.

It was pure peacocking. "Land Rover delivers without dilution" said McGovern. "If design comes first we produce fur coat cars" replied Rogers.

Wheel Tire Motor vehicle Font Car


Tire Car Wheel Vehicle Land vehicle

Organism Wood Terrestrial plant Font Plant


It was all so avoidable. If only they'd listened to their engineers.....
 

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#130 ·
Trojan said:
Ah, yes, neck ties. People who know what went on will tell you off the record that Design refused to give Engineering the space they needed to fit the XE DPF behind the transverse Ingenium engine. That decision was, as we know, the single root cause behind all these problems. Now, who was it that made the decisions back then? Who reported to whom? So who ultimately signs off the engineering decisions today?
While it's nice and convenient to blame the evil corporation and the cravat for greed I don't think that is the real reason.

When the Ingenium was being developed for the DS & Evoque, Dieselgate had not yet happened. This I think is important as pre-Dieselgate, most manufacturers were running their engines hotter via the ECU as that produces much less soot, and gives the DPF an easier time. The downside of this is that when run hotter, the engines produce way more NOx. Once they got caught cheating because NOx levels were way higher than they should be (not by small amounts either) then the 'fixes' started to make cars behave like the DS ....

The timing for LR was the worst it could have been, exactly when they were about to launch their new engines. So in order to not get caught up in Dieselgate they have to reconfigure the ECU to be emissions compliant which reduces the engine operating temperature, a double whammy for the DS as now the SCRF is too far away for reduced temps to be at all effective for any kind of passive regeneration, and lower engine temps produce more soot. So with zero passive regeneration to help keep increased soot levels down, DPF's clog more easily and all owners get oil dilution to varying degrees.

The Netflix documentary sums this up perfectly I feel. VW did this to become the no.1 car manufacturer in the world, i.e to gain market share. Where are they now? :) In spite of all the fines, their goal was achieved and they forced all other manufacturers to either quit diesel or copy them to stay competitive. JLR got burned badly.

Unfortunately their soot didn't get burnt at all....
 
#131 ·
Parkers Guide update 16th September 2019 for 20MY Discovery Sport. The following on Running Costs and mpg

* Poor fuel economy overall
* Servicing costs are competitive
* Diesel models now have larger fuel tank

Running costs for the Land Rover Discovery Sport really aren't anything to get excited about. Official fuel economy for the 250hp petrol that we drove is just 30.5mpg - and on our spirited driving route we saw an average figure in the mid-teens. That's really poor for a comparatively small SUV, and can probably be accounted for by the car's vast weight. Range-topping diesel models come in at more than 2 tons, unladen - this car really is a porker.

The diesels provide more palatable running costs, with a combined figure of 39.6mpg for the 240hp model we drove. That's still not fantastic, though, especially when compared with a car like the Skoda Kodiaq which easily achieves in the mid-40s and beyond.

Those looking for the cheapest running costs should opt for the very entry-level model, which has front-wheel drive and a manual gearbox only. The reward for losing all that capability is a fuel economy figure of 47.8mpg. CO2 emissions for this car go as low as 140g/km, but opting for the range-topping petrol will see this figure skyrocket to 179g/km, despite the mild-hybrid tech.

Reliability

* Previous Discovery Sports were not reliable
* Latest engine tech may fix diesel emissions issues
* Land Rover doesn't have the greatest reputation

The pre-facelift Land Rover Sport notched up a fairly unenviable reputation for poor reliability. These related in the most part to the diesel emissions systems of the 2.0-litre diesel engine - they failed, contaminating the engine oil and potentially damaging the engine.

Land Rover offered a goodwill gesture to affected owners, but sadly that's not been the last of the Discovery Sport's issues. Disappointingly, many owners have reported creaks and rattles from brand new cars, and other issues such as balancer shaft bearing failure. All of these you ought to bear in mind if considering a used Land Rover Discovery Sport - and if buying new, be sure to service the car within the terms of the warranty so that you have some cover should things go wrong.
https://www.parkers.co.uk/land-rover/discovery-sport/review/mpg-running-costs/
 
#132 ·
Ian_S said:
Trojan said:
Ah, yes, neck ties. People who know what went on will tell you off the record that Design refused to give Engineering the space they needed to fit the XE DPF behind the transverse Ingenium engine. That decision was, as we know, the single root cause behind all these problems. Now, who was it that made the decisions back then? Who reported to whom? So who ultimately signs off the engineering decisions today?
While it's nice and convenient to blame the evil corporation and the cravat for greed I don't think that is the real reason.

When the Ingenium was being developed for the DS & Evoque, Dieselgate had not yet happened. This I think is important as pre-Dieselgate, most manufacturers were running their engines hotter via the ECU as that produces much less soot, and gives the DPF an easier time. The downside of this is that when run hotter, the engines produce way more NOx. Once they got caught cheating because NOx levels were way higher than they should be (not by small amounts either) then the 'fixes' started to make cars behave like the DS ....

The timing for LR was the worst it could have been, exactly when they were about to launch their new engines. So in order to not get caught up in Dieselgate they have to reconfigure the ECU to be emissions compliant which reduces the engine operating temperature, a double whammy for the DS as now the SCRF is too far away for reduced temps to be at all effective for any kind of passive regeneration, and lower engine temps produce more soot. So with zero passive regeneration to help keep increased soot levels down, DPF's clog more easily and all owners get oil dilution to varying degrees.

The Netflix documentary sums this up perfectly I feel. VW did this to become the no.1 car manufacturer in the world, i.e to gain market share. Where are they now? :) In spite of all the fines, their goal was achieved and they forced all other manufacturers to either quit diesel or copy them to stay competitive. JLR got burned badly.

Unfortunately their soot didn't get burnt at all....
This is far too complicated. The simple explanation been staring us in the face for 2 years ever since JLRP00100, now confirmed by another JLR letter. It is about the heat sink effects of 70 cm of additional pipework.

Fact - If the DS had used the DPF from the XE it would never have suffered from oil dilution, short service intervals and DPF clogging.

The mistake(s) that led to this appalling cock-up came from someone at Jaguar Land Rover, not VW. ;)
 
#133 ·
Trojan said:
This is far too complicated. The simple explanation been staring us in the face for 2 years ever since JLRP00100, now confirmed by another JLR letter. It is about the heat sink effects of 70 cm of additional pipework.

Fact - If the DS had used the DPF from the XE it would never have suffered from oil dilution, short service intervals and DPF clogging.

The mistake(s) that led to this appalling cock-up came from someone at Jaguar Land Rover, not VW. ;)
^ ^ ^ ^ ^ ^ This ^ ^ ^ ^ ^ ^

Look at the new Defender. It has a single DOC-DPF device strapped to the turbo with downstream DEF-SCR. JLR has always known that this is the best arrangement. It's simple and it works. It worked for EU5 in 2012 and it still works for EU6 in 2020.

We have all suffered because SCRF was a Heath-Robinson contraption knocked together in a financial hurricane. All because someone forgot to get their tape measure out....

...or, more likely, they DID measure it but someone else with neckwear insisted that "undiluted design" was more important than "undiluted oil".
 
#134 ·
Trojan said:

Fact - If the DS had used the DPF from the XE it would never have suffered from oil dilution, short service intervals and DPF clogging.
It's not really fact though, because the other countering fact is that the close mounted DPF used in the XE is there purely because the engine is mounted longitudinally and therefore has the space. The DS does not have the space.

Whether we like it or not, the reason the DS has the architecture it has is because it is based on the Evoque, and therefore any EU6 solution had to fit both cars (and the E-Pace). So there was no clean sheet of paper, and the extra gubbins for NOx removal needed to go somewhere. This is also why the DS was updated so quickly after the Evoque this time as that sharing is quite deep rooted. I'm surprised the E-Pace is not also being updated already.

I'm still going to give the benefit of the doubt to JLR's engineers and don't believe they are incompetent, and that if the engine ran hotter than it does now, that the SCRF solution may have been better. Not perfect, but maybe better enough to allow some passive regeneration.

And again, you can't use the Freelander or other EU5 cars as an example because they all ran their engines much hotter and have all been real-world tested and shown to produce massively more NOx than they should be. That is the direct impact of running the engine hotter, more NOx, less soot, easier time for DPF, more flexibility on where DPF can be, 500 miles instead of 250 between active regens (so less dilution) and less time required to complete one because you generate less soot to start with and passive regens work.

How JLR have handled the problem though is a different matter.... you can fill your boots there. :)
 
#136 ·
Ian_S said:
Trojan said:

Fact - If the DS had used the DPF from the XE it would never have suffered from oil dilution, short service intervals and DPF clogging.
It's not really fact though, because the other countering fact is that the close mounted DPF used in the XE is there purely because the engine is mounted longitudinally and therefore has the space. The DS does not have the space.
I disagree. The available evidence does support the hypothetical premise:

If the DS had used the DPF from the XE it would never have suffered from oil dilution, short service intervals and DPF clogging.

But without moving the hard points you are correct to say that it lacks the space. None of the D8 cars have the space required for the Ingenium engine AND a close-coupled DPF. But this didn't stop them trying.

This lack of space (it's just an inch or so) was something that simply got over-looked during an extremely busy period when they were trying to get ten nameplates simultaneously through the EU6 type approval process. It was assumed that, since the Ford/PSA 2.2 Duratorq engine snuggled neatly into the available space in the Evoque and Freelander, not to forget the first 45,000 or so Discovery Sports (UK up to GH516413), together with its close-coupled DPF, then it followed that the transverse AJ200D would fit neatly into the L550 - and into the L538 in due course.

It was a small oversight. But it had enormous consequences.

Two years ago someone claimed to have an engineering source (L550 powertrain design team) that gave them this information via a dealership. Today I can match that with confidential written communications that convey precisely the same information. You can say that all these people are lying, that their memories are unreliable or you can say that I am lying, but otherwise the evidence is what it is. Importantly their evidence is corroborated by JLR documents, as we shall see.

Whether we like it or not, the reason the DS has the architecture it has is because it is based on the Evoque, and therefore any EU6 solution had to fit both cars (and the E-Pace). So there was no clean sheet of paper, and the extra gubbins for NOx removal needed to go somewhere.
Yes, the "extra gubbins" for EU6, that is to say the DEF injector and the 3-way SCR, always go underneath the car because that's the ideal position for them. Look at all the other cars that JLR produce. But JLR's engineers were not idiots - they knew what would happen to soot management if the DPF was also stuck down there in the cold airflow. At some point late on in the development process JLR planned for the L550 to have the DOC-DPF-DEF-SCR architecture. It works best because it places the DOC-DPF pair as close to the engine as possible. In 2015 JLR produced this schematic for the Discovery Sport L550 AJ200 diesel.

[IMG=https://www.discosportforums.co.uk/download/file.php?id=8362][/IMG]

This diagram corroborates the accounts of anonymous JLR witnesses. In 2015 at least one part of JLR was still forging ahead with a design that had the exhaust hardware components arranged exactly as they are on the XE. Look at the date on the files: 15th May to 21st July 2015. What other explanation could there be for this document ? In any cogent explanation this document has to be addressed, it cannot be simply swept aside as if it were a forgery or otherwise irrelevant. So what is it describing if not the XE system applied to the DS chassis?

As for the under-floor "gubbins" for NOx reduction, have a look at this diagram. The vehicle in the picture clearly isn't a Jaguar XE. Then look at the accompanying text: Overview The Selective Catalyst Reduction system is an exhaust aftertreatment system used to reduce the nitrogen oxides within the exhaust gas. For this purpose, a specified amount of Diesel Exhaust Fluid (DEF) is injected into the exhaust system, downstream of the DPF... read that again, slowly.... "downstream of the DPF...." Look where the DEF injector (7) is positioned on the downpipe. Think where the DPF has to be located in order to be "upstream" of it. Remember that this is a diagram of a Discovery Sport that you are looking at.




This is also why the DS was updated so quickly after the Evoque this time as that sharing is quite deep rooted. I'm surprised the E-Pace is not also being updated already.
Agreed.

I'm still going to give the benefit of the doubt to JLR's engineers and don't believe they are incompetent, and that if the engine ran hotter than it does now, that the SCRF solution may have been better. Not perfect, but maybe better enough to allow some passive regeneration.
If they'd been able to use the XE DOC-DPF device attached to the turbo as per the provisional workshop manual extract depicted (there's no HP EGR to get in the way on the planned architecture because LP EGR is tapped off after the SCR) the SCRF® would have been unnecessary. No-one is saying that the engineers were incompetent. The suggestion is that they were asked to pull off the impossible. They tried their hardest to create an alternative system but they couldn't make it work with the DPF located so far away from the engine. Physics. Chemistry, Thermodynamics. Talented engineers proved no match for the immutable laws of nature,

What is suggested is that senior executives knew that there were massive risks of failure with the "alternative exhaust" project and that they pushed sales and marketing plans forward against the advice of their engineers. Where are the people concerned today? It's an excellent question. They are probably reading this. If they disagree with the views expressed they are at liberty to offer their alternative evidence. If this is the wrong interpretation, why doesn't JLR correct the record?

We could also legitimately ask why JLR used the L550 production vehicle as a test platform for coatings that were still at the prototype stage of development. A year after the Discovery Sport Ingenium was launched, the coatings manufacturer gave a presentation in America which ended with speculative statements about possible ways to improve known shortcomings of the SCRF® system. This happened a year after it was being fitted to production cars? I wish I was joking. What shortcomings had they identified? Well how about this, for starters. "The SCRF® catalyst can be fully regenerated (95%) in ~30 mins at 600°C". That was the state of play for SCRF® in 2016, according to the manufacturer.

How good is 95% regeneration in approximately 30 minutes? It is rubbish. It compares to a full - i.e.100% - regeneration at 600°C in 20 minutes for a catalysed soot filter (CSF) - i.e. like the DPF device used on the XE. So a 50% longer burn is needed with a SCRF® compared to a CSF and it still can't clear the filter completely. This would no doubt have been explained to the management in words of one syllable when the decisions to use it in the L550 and L538 were being taken. But still management didn't catch on. Maybe the chemists at the party were more convincing in persuading management that this new SCRF® technology could break the laws of nature. Maybe they said the engineers were "stuck in the past". Who knows? The engineers were over-ruled is all we can say.

And again, you can't use the Freelander or other EU5 cars as an example because they all ran their engines much hotter and have all been real-world tested and shown to produce massively more NOx than they should be. That is the direct impact of running the engine hotter, more NOx, less soot, easier time for DPF, more flexibility on where DPF can be, 500 miles instead of 250 between active regens (so less dilution) and less time required to complete one because you generate less soot to start with and passive regens work.
All of those obstacles were overcome with the XE exhaust. It uses minimal post injection for DPF regeneration and the car makes it comfortably to the extended service intervals The DPF's are not known for clogging or failing. If the XE exhaust architecture had been fitted to the L550 - as JLR documentation shows clearly was still intended between 15th May and 21st July 2015 - then it, too might have performed flawlessly and in doing so fulfilled every one of the claims made for it in the brochure.

The sickening part of this is not that the Discovery Sport failed to live up to the promises contained in the brochure. It's that when it didn't (for understandable reasons), instead of taking responsibility and putting things right, this miserable little company then spent four years blaming its customers' "driving style" while using every trick in the book to hide what it had done.

Perhaps the Serious Fraud Office ought to be reading this as well.

Published: 21-Jul-2015
Exhaust System - INGENIUM I4 2.0L Diesel - Selective Catalyst Reduction
Description and Operation
View attachment 8363
 

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#137 ·
The first DS with Ingenium and SCRF® shipped in September 2015. Here's a taste of the evidence that SCRF® was still undergoing significant development in 2016. Our 16MY and 17MY diesels were, in effect, JLR's test platforms.

Rectangle Font Circle Paper Auto part

Azure Font Screenshot Number Rectangle

Rectangle Font Line Parallel Screenshot

Font Parallel Poster Rectangle Advertising


View attachment 6778
 

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#138 ·
@Resdiscovery ...

Having worked for several large corporations, documentation is usually written by technical writing teams, and the non-specific block diagram is likely to be nothing more than a simple copy and paste job on the grounds that at the block level, it's largely correct. For the XE you could put a further box round the DOC and DPF and for the DS you would put the extra box round the DPF and. SCR elements instead. The document for the 'DPF' operation uses the block diagram. The document for the SCR system, or NOx after-treatment system uses diagrams showing the placement of actual components in the DS itself.

You could start to get really pedantic here and say well both documents are in effect in-accurate because there is neither a separate DPF, OR, a separate SCR system, they are combined in an SCRF, which is identical in shape to the component highlighted in red under the DS floor pan. I doubt very much that the XE SCR system component looks like the DS SCRF. And the main reason they will still discuss these high level systems (DPF and SCR) separately is because that's how everyone understands them. Everyone here still talks about DPF replacement, but really it's an SCRF replacement. (Part of the reason it'll be more expensive too.)

So personally I don't see that either of those documents show any clear evidence of JLR having developed a close coupled DOC-DPF solution and changed their mind at the last minute. It seems more likely that someone simply re-used a block diagram, and someone else wrote the NOx after treatment part later showing the actual components that were being used. Yes in 2013 the original intention may well have been to use a DOC-DPF, but I bet they found pretty quickly that it didn't fit the Evoque, and I also bet that everyone from design and engineering wanted to share the same system between the Evoque, DS and E-Pace if the latter was on the drawing board at that stage. All guesses of course ...

The more interesting things in what you've posted are the lack of efficiency in the SCRF in cleaning the soot, and the fact that it never seems to actually manage 100%. Also not much mention of any passive cleaning. Another interesting question for an SCRF is can you clean the ash from it like you can a more standard DPF? If you can't then that implies once it's full of ash, it's a new SCRF.... which as we know is expensive. Not great news for long-term owners and also does the absence of 100% soot burning even after 30 mins mean that the soot filter part of the SCRF has a shorter working life than a seperate DOC-DPF solution?
 
#139 ·
Ian_S said:
@Resdiscovery ...

Having worked for several large corporations, documentation is usually written by technical writing teams, and the non-specific block diagram is likely to be nothing more than a simple copy and paste job on the grounds that at the block level, it's largely correct. For the XE you could put a further box round the DOC and DPF and for the DS you would put the extra box round the DPF and. SCR elements instead. The document for the 'DPF' operation uses the block diagram. The document for the SCR system, or NOx after-treatment system uses diagrams showing the placement of actual components in the DS itself.

You could start to get really pedantic here and say well both documents are in effect in-accurate because there is neither a separate DPF, OR, a separate SCR system, they are combined in an SCRF, which is identical in shape to the component highlighted in red under the DS floor pan. I doubt very much that the XE SCR system component looks like the DS SCRF. And the main reason they will still discuss these high level systems (DPF and SCR) separately is because that's how everyone understands them. Everyone here still talks about DPF replacement, but really it's an SCRF replacement. (Part of the reason it'll be more expensive too.)

So personally I don't see that either of those documents show any clear evidence of JLR having developed a close coupled DOC-DPF solution and changed their mind at the last minute. It seems more likely that someone simply re-used a block diagram, and someone else wrote the NOx after treatment part later showing the actual components that were being used. Yes in 2013 the original intention may well have been to use a DOC-DPF, but I bet they found pretty quickly that it didn't fit the Evoque, and I also bet that everyone from design and engineering wanted to share the same system between the Evoque, DS and E-Pace if the latter was on the drawing board at that stage. All guesses of course ...

The more interesting things in what you've posted are the lack of efficiency in the SCRF in cleaning the soot, and the fact that it never seems to actually manage 100%. Also not much mention of any passive cleaning. Another interesting question for an SCRF is can you clean the ash from it like you can a more standard DPF? If you can't then that implies once it's full of ash, it's a new SCRF.... which as we know is expensive. Not great news for long-term owners and also does the absence of 100% soot burning even after 30 mins mean that the soot filter part of the SCRF has a shorter working life than a seperate DOC-DPF solution?
[IMG=https://www.discosportforums.co.uk/download/file.php?id=8360][/IMG]
[IMG=https://www.discosportforums.co.uk/download/file.php?id=8361][/IMG]

This is not a block diagram. It is a CAD/CAM extract dated 21st July 2015. The vehicle is clearly a L550 Discovery Sport. We can't see the DPF but we can see the DEF injection point (7) and we can all read the words.

The Selective Catalyst Reduction system is an exhaust aftertreatment system used to reduce the nitrogen oxides within the exhaust gas. For this purpose, a specified amount of Diesel Exhaust Fluid (DEF) is injected into the exhaust system, downstream of the DPF.

You presumably understand the meaning of "downstream" as well as I do. It means that in this 21st July 2015 drawing, the DPF (it is clearly visible adjacent to the bulkhead in another drawing that I can post) is above the injector, close to the engine. DOC-DPF-DEF-SCR. These words and pictures match what engineers have said happened. Why are there no words and pictures describing SCRF to the same level of detail? Perhaps because it was only invented in 2014 and was still basically a prototype when these drawings were produced?

As JM's presentation shows, this was still novel technology that was incapable, more than one year after the events we are debating, of completing a full regeneration inside 30 minutes. So JLR would have known this in 2015, wouldn't they? This is the pincer moment. Whatever the "preferred" choice of architecture in July-August 2015 JLR had left itself in an impossible position because, having denied the powertrain engineers the space they needed, it found itself having to choose between:

1) a workable design that met the spec but didn't fit without the risk of setting fire to the car;
2) prototype hardware that could be made to fit but didn't work according to spec (and never would), or
3) suspending L550 production until there was a design that both fitted and worked.

For purely commercial reasons JLR decided it was better to go with option 2, hide the problem for as long as possible (normally 2 years) and then blame diesel dilution and clogged DPFs on the driving style of anyone who had the temerity to challenge the quality of a JLR product.

Not pretty.
 
#140 ·
Rediscovery said:
This is not a block diagram. It is a CAD/CAM extract dated 21st July 2015. The vehicle is clearly a L550 Discovery Sport. We can't see the DPF but we can see the DEF injection point (7) and we can all read the words.
Come on ... :D

Clearly by block diagram I meant the first diagram in your initial post copied below... Let's call this Diagram 1.

[IMG=https://www.discosportforums.co.uk/download/file.php?id=8362][/IMG]

The diagram you quote in the post before this one, which as you say is clearly some kind of CAD export comes from the SAME document, so let's call that diagram 2. As I Previously stated, in diagram 1, if we are going to take it as gospel, it is in fact incorrect for either the XE or any close coupled DOC-DPF arrangement (DOC is item 10, DPF is obviously item 9) as these tend to be in the same box. Likewise it's also incorrect for what is in the DS, Evoque etc. as in that arrangement 6, the SCR and 9, the DPF are in the same under-body component and the DOC (10) is close mounted to the engine.

Diagram one is clearly a generic block or schematic on the overall components in a system and their rough interaction. I can't agree that this is enough to conclude they were still pursuing a close coupled DOC-DPF unit as per the XE. To further illustrate you can easily find the following diagram also from July 2015 on the 'DPF'... Let's call this diagram 3.

Arm Leg Human body Font Automotive exterior


Looking at both diagram 2 and 3 we can see quite clearly that the same component, the SCRF (combined SCR and DPF function), is described as either the SCR (Item 8, diag 2) or DPF (item 4, diag 3) depending on whether you are looking at the DPF system document or the SCR system document. It is in the same place and the same shape on both the DS CAD drawings.

So again I stand by what I said that if we want to be really picky, both CAD diagram parts lists are incorrect, and we shouldn't refer to a DPF or SCR on the DS, but instead SCRF which combines the two. For me the simple explanation is that diag 1 is a generic schematic probably used in many places and that diag 2 and diag 3 are used differently to highlight ancillary components that apply only to that function and also because people understand what a DPF is...

None of which is trying to refute anything you've said about the SCRF operation and the clear demonstration of how in-efficient it is. That information is both very useful and dis-heartening in equal measure.

We can only hope if this architecture is still present on the new DS and Evoque, that SCRF technology has improved massively since 2015-16 and that it has solved some of the issues. Else this nightmare will persist for many. Can't see who wins there.
 

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#141 ·
Possibly....

Diagram 3 confused me for a while when I first saw it. I think it's easy to explain though: it's simply the DOC-DPF architecture for EU5 markets where SCR was irrelevant, even after 1st September 2015. No NOx to worry about? Then crank up that heat boys!

I think I am on the same page, with reservations. I think we agree that the schematic represents the original design intent, provided that you accept that a functional schematic with oxy-cat (DOC) and catalysed soot filter (DPF) shown as two boxes is not invalidated if, for heat preservation, they combine these functions into a single canister, wherever possible. Better still if the DOC can attach directly onto the turbo. Of the more popular cars this accounts for D7a (XE, XF, F-PACE, and Velar). "close coupled so minimal or no effect" and D7u (RR, RRS and Discovery). medium coupled, may suffer from Oil Dilution.. They're all single canister arrangements and imho they all conform to the schematic in this document.

But I think the functional schematic was rendered useless once the decision had been taken to go with the SCRF system for D8 and at some point they had to abandon the preferred order of the functions. This is because SCRF puts the SCR on the filter which means that the DEF has to come before both. The fact that it says the opposite in the text I think identifies the point at which there had to be a departure. For me the date is still difficult to ignore.

We appear to be left with timing. The argument that SCRF was designed in earlier, rather than later, is somewhat weakened by the fact that this appears to have been very new, untried, technology which clearly needed further improvements in 2016. I think that speaks volumes about its suitability and readiness to be incorporated into a production system in the spring/summer of 2015 ( over a year earlier ). If that was 2015, what on earth was it like in 2014?

The other things that make it difficult to imagine that the crappy SCRF system was fully incorporated into their earliest plans, rather than being forced on them late in the day:
* The hopelessly misleading brochure claims echoing Jaguar XE service performance.
* The comments about "higher than expected" dilution in JLRP00100.
* The disclosures in the letter to dealer sales staff.
* No dealer software, training or worksheets for the known servicing requirements of SCRF.
* Waiting until 2018 to change the dilution to 10% - if they'd known this was coming a lot of grief could have been saved by doing this in 2015.
* AdBlue usage doubled.
* Disappointing fuel economy.

They could have been planning a cheat device to overcome some of these, I know, Anyway, thanks for the chat. I have it on good authority that someone on here does know the answer to the timing issue. Perhaps at some point they'll generously share what they know about the events at Gaydon in 2015... :)
 
#142 ·
I think you're seeing what you want to see and that we're going to have to agree to disagree with the diagrams. :) The only thing we can conclude IMO is they are way too woolly and inexact to be able to take them literally.

It is interesting to look at some regulatory timelines though.

September 2014 - All new type approvals must be EU6 compliant
September 2015 - All new car registrations must be EU6 compliant
September 2017 - EU6 compliance of no more than 2x limit comes into force
September 2019 - RDE comes into effect.

So, the DS is 'launched' in April 2014, when no doubt it gains type approval giving LR some leeway in starting sales with an EU5 engine, while they continue to grapple with EU6 emissions. They start selling cars late 2014.

Ingenium has to be in the car by September 2015 (MY 2016) or they just can't sell them, likewise the Evoque.

DEF usage in MY17 cars and later seems to increase after software updates... 2x compliance factor anyone? MY16 cars now consume DEF at half the rate of MY17 onwards with the same DEF tank size.

MY20 DS arrives for RDE. What changes lurk within?

I think we all realise that a DOC-DPF doesn't fit in the engine bay. It's a little disappointing that it would appear that hasn't changed on the new DS and Evoque.

Is there another fix though? It's clear from all the documents that an SCRF is far less efficient at burning off soot than a more standard DOC-DPF unit. The only hope for improvement there is that the filter technology, i.e. coatings improve to allow more efficient burn off. One option would be to use more fuel to spend more time actively regenerating the SCRF but, that would make the oil dilution even worse. So not really an option....

Or is it... ?

The reason we get oil dilution is because the fuel is injected in the cylinder by the existing injectors. Hence some of it (more than we'd hoped) finds its way down the cylinder wall. We know there is not enough space to replace the DOC assembly with one that contains a DPF, and a change to the chassis to accommodate that would also rule out any kind of retro fit option.

So, why not use that pesky bit of extra pipe work that robs the system of heat to fit a fifth injector purely for active regeneration? That would surely fit. OK, we'd need a new injector rail with a fifth outlet, a replacement DOC assembly that could house the injector (unless you could add a hole to the in-situ one reliably) and also the existing ECU would need to be able to control said injector, *but*, if that could be done, then the ECU could be far more aggressive with it's active regeneration policy as it would no longer have to worry about excessive oil dilution. The main downside would be fuel economy to fund the increased active regeneration, but I think I'd rather have that than a blocked DPF or failed engine. Once you'd got the system working it would be retrofit-able to existing troublesome cars .

It could be a barking mad idea... but you never know...

I only suggest it as it seems the underlying tech chosen in these cars will never perform that brilliantly and options to regen the DPF even more are limited by oil dilution. Remove the dilution and are there then more options in ECU software to help the DPF?
 
#143 ·
Iain
I looked into this many moons ago , you need to look more closely at the categories, it's not quite as simplistic as
"
It is interesting to look at some regulatory timelines though.

September 2014 - All new type approvals must be EU6 compliant
September 2015 - All new car registrations must be EU6 compliant
September 2017 - EU6 compliance of no more than 2x limit comes into force
September 2019 - RDE comes into effect. "

Eu 6 a/b/c/d all have specific conditions attached
Timelines for full compliance are conditions attached to the suffix.

This was when EU6b to 6c doubled adblue useage...around 2017.
Eg they get issued as 6x compliance with the aim of being fully compliant with in y months.
 
#144 ·
Regarding the potential for passive regeneration on the DS...

In the attached 2015 paper JM scientists explain that passive regeneration at 200°C to 400°C would be "significantly retarded" whenever SCR NOx treatment was also "active" due to the competition for NOx (this was still an issue in 2016). Their "experimental results" were presumably obtained on a compact architecture where 400°C might actually have been achievable ("compact" in this context not the same as "close-coupled" referring to DEF-DPF architectures).

There are two main problems frustrating passive regeneration on the D8 architecture:
* The "normal driving" temperatures are in the lower half of the 200°C to 400°C range (due to 70 cm of additional pipework).
* Soot oxidation is in any case "significantly retarded" during SCR activity due to competition for NO2.

When JLR stated in 2017 that "normal" driving didn't create enough heat for passive regeneration to occur they would have already processed this information. They would also have been aware that in 2016 JM still hadn't overcome several major obstacles:

* CSF has higher passive soot oxidation > 270°C compared to an SCRF® catalyst";
* The soot burn efficiency in a CSF is significantly higher than an SCRF® catalyst under active regen conditions (550°C to 600°C);
* The higher soot burn efficiency observed for the CSF compared to the SCRF® catalyst under active regeneration conditions can be attributed to the NO2 produced in the CSF (no competition);
* 600°C / 30 minute regen for the SCRF® catalyst matches the same regen efficiency as that of a 600°C 10 min regen for the CSF;
* 600°C for 20 minutes will only get you to about 75% soot burn on engine;
* The SCRF® catalyst can be fully regenerated (>95%) in approximately 30 minutes at 600°C;

… and asking / proposing:

* We need to adapt a suitable active regeneration strategy;
* How do we overcome the thermodynamic equilibrium limitation of producing sufficient NO2 under active regeneration conditions for reaction with soot?
* Increasing filter inlet temps to >600°C will be beneficial to reduce length of regeneration event;

This product was clearly still not finished more than one year after DS EU6 production started.

One point of interest with SCRF® is the interaction between the NOx reduction (SCR) and soot oxidation functionalities; NOx removal results in a reduction in the availability of NO2 for soot oxidation, while soot oxidation by NO2 lowers the NO2/NOx ratio, which is unfavourable for SCR if it moves away from the optimum value of 0.5. Therefore the SCRF® model has been applied to investigate this. The presence of soot on the SCRF® is predicted to have no significant impact on NOx conversion.

Conversely, SCR activity (NOx reduction) is predicted to significantly retard the rate of soot removal at lower temperatures (200°C-400°C), where soot oxidation is predominantly by reaction with NO2, but to have little effect at higher temperatures (450°C-550°C), where soot is predominantly oxidised by O2. Both predictions are in agreement with experimental results.
Computer Simulation of Automotive Emission Control Systems
Key developments in modelling of diesel emissions control components and catalysts are highlighted

View attachment 9684
 

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#145 ·
As a picture tells a 1000 words... (ANR = 0 means no SCR activity, ANR = 1 means SCR is actively converting NOx)

Rectangle Slope Font Plot Parallel


So below 250C passive soot burn-off is negligible even after 60 mins. Looks like you regularly need to exceed 300C to stand any chance of making a dent in the soot build up and reach the maximum of 250 miles before the next scheduled active cycle will begin anyway.

I wonder if later SCRF units have improved filter chemicals that perform better at lower temperatures.

I also wonder what performance would have been like in 'cheat mode' where we know the engine would produce more NOx and also remove less in the after-treatment. It looks like in that scenario, you might actually get some passive regen, especially if they also ran it hotter to produce less soot and also increase exhaust temps? Looks like a win-win to me. Higher engine burn temp = less soot = more NOx = higher exhaust temp = better passive regen and turn down the SCR wick and less competition for NOx to prevent passive regen.

However, the evidence all seems to suggest that for diesels, by far the most effective solution is a combined DOC-DPF and separate SCR system. One thing done at a time with the chance to optimise each process and not have to cheat to make it all work effectively.

It's looking more and more disappointing that the new platform hasn't tried to properly address this in the new models. The best we can hope for is that the active regeneration has improved enough to be able to work in challenging situations, especially as the new Evoque is being heavily advertised for use in the Urban Jungle... I guess the first indicator of better active regeneration will be fewer blocked DPFs in urban driving.

I suspect it goes without saying that the new models will be using the 10% oil dilution threshold from the start in the hope it gets most people past the 12 months point, which is probably the line where 'early' oil changes become more acceptable.

I wonder who else uses an SCRF?
 

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#146 ·
I don't know of another auto manufacturer using SCRF apart from JLR. And JLR only used it because it had no choice, remember.

I think you are right about the defeat devices. One raises the temperature in the SCRF to shift along the curves to the right. The other turns SCR OFF to keep PR on the blue curve.

And DEF usage would then be more appropriate for the size of tank.

Push SCRF temperature towards 650 deg C and it would make a significant improvement in AR to boot.
 
#147 ·
Ian_S said:
So, why not use that pesky bit of extra pipe work that robs the system of heat to fit a fifth injector purely for active regeneration? That would surely fit. OK, we'd need a new injector rail with a fifth outlet, a replacement DOC assembly that could house the injector (unless you could add a hole to the in-situ one reliably) and also the existing ECU would need to be able to control said injector, *but*, if that could be done, then the ECU could be far more aggressive with it's active regeneration policy as it would no longer have to worry about excessive oil dilution. The main downside would be fuel economy to fund the increased active regeneration, but I think I'd rather have that than a blocked DPF or failed engine. Once you'd got the system working it would be retrofit-able to existing troublesome cars .

It could be a barking mad idea... but you never know...
That's the way most commercial diesel's regenerate their DPFs. The reason normally given for not using it in cars is the extra expense and limitations in space. But, Toyota have tried it on SUVs and pickups equipped with their 2.8L diesel and the results haven't been good. Apparently they've had problems with the fifth injector getting stuck closed or open. The former results in no regeneration, a blocked DPF, and limp-home mode. The latter isn't much better and results in excess fuel consumption and a fried DPF as it's regenerating all the time! It's currently the basis of a class action lawsuit against Toyota in Australia involving 250,000 cars. Just goes to show there's no easy answer to making a DPF that simply works!
 
#148 ·

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#149 ·
Regarding the suggestion made above and elsewhere that late/forced removal of a NOx cheat device upped the HC/PM output, thereby triggering problems with oil dilution, DPF clogging/premature failure, EGR faults, etc.

A letter from Dept for Transport explains what happens to VAG cars after the removal of their EDC17 cheat devices. Font Material property Parallel Screenshot Paper
Font Material property Parallel Paper Paper product
Rectangle Font Parallel Paper product Paper


So far I can only find this rather poor copy which came from https://www.hypermiler.co.uk/dieselgate/dieselgate-department-for-transport-confirms-vw-fix-causes-twice-the-level-of-carcinogenic-diesel-particulate-matter

The data corelates precisely: three times as much soot, double the amount of active regeneration, soot up the EGR channel. I've read the Guardian account but that contained only anecdotal evidence. This is official data from the DfT and it seems to match the owner-provided data on here.

Put a cheat device on the L538/L550 2.0) diesels and everything would have worked fine. Just like it said in the brochure.
 

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#150 ·
Ian_S said:
I wonder if later SCRF units have improved filter chemicals that perform better at lower temperatures.
...
However, the evidence all seems to suggest that for diesels, by far the most effective solution is a combined DOC-DPF and separate SCR system. One thing done at a time with the chance to optimise each process and not have to cheat to make it all work effectively.
...
I suspect it goes without saying that the new models will be using the 10% oil dilution threshold from the start in the hope it gets most people past the 12 months point, which is probably the line where 'early' oil changes become more acceptable.
...
I wonder who else uses an SCRF?
VW, ably assisted by Bosch, developed a cheap system that achieved NOx compliance during testing (with cheat device) but gassed people out on the road. When they were caught out they came up with the infamous VW "fix". But when this was applied, according to an official DfT letter, soot production tripled and active regeneration (and hence oil dilution) doubled.

It has been hypothesised that JLR, originally planning to follow VW's lead, simply skipped the cheating stage and went straight to selling cars suffering from high oil dilution, short service intervals, DPF clogging and EGR faults. Like VW, these are problems caused by too much soot in the absence of a cheat device.

JLR today? Same 5 year-old system. One remote, too-cool, SCR-on-filter catalyst under the car, 10% oil dilution. No longer possible to sell as suitable for rural/urban driving. PTA redevelopment window ignored.

VW today? Obviously they want to continue selling diesels to everyone, regardless of where they live. So, like Mercedes, they threw some money at it. Twin SCRs, the first one appears to be SCRF and guess what? It's right behind the DOC which in turn is bolted directly onto the engine turbo outlet. Wish CG was here.

Volkswagen introduces dual SCR technology on diesel cars

Volkswagen has introduced a dual SCR catalyst configuration on diesel vehicles, which enables meeting the Euro 6d (2020/2021 for new types/all vehicles) emission standards. The new aftertreatment configuration, dubbed "twin-dosing", was first used in the updated 2019 Passat 2.0 TDI Evo with 110 kW (150 PS) power output. Volkswagen intends to gradually introduce the dual SCR technology to all models with 2.0 TDI Evo engines, including the coming new VW Golf in all its TDI variants.

In RDE (real driving emissions) measurements, NOx emissions from the new 2.0 TDI Evo with dual SCR were reduced by around 80% compared to the previous generation of the vehicle, according to Volkswagen.

Compared to the earlier configuration, the new aftertreatment system includes a second SCR catalytic converter which is located in the underbody of the vehicle, followed by an ammonia oxidation catalyst (ASC). As the exhaust temperature in the underfloor position can be as much as 100°C lower than that close to the engine, this expands the temperature window for the SCR system-even at exhaust gas temperatures close to the engine of +500°C, the system is still able to achieve very high conversion rates, Volkswagen said.
White Automotive lighting Font Machine Auto part


In the earlier configuration, only one, close-coupled SCR catalyst was used-applied onto the diesel particulate filter (SCRF)-and positioned downstream of the turbocharger and a diesel oxidation catalyst (DOC). In this close-coupled arrangement, the exhaust gas temperatures required for high conversion rates can be achieved quickly after a cold start-the ideal range for conversion rates of more than 90% is between +220°C and +350°C.

Thanks to the second, underfloor SCR catalyst, the new system can maintain high NOx conversion rates above +350°C as well. Temperatures at this level occur for example when driving at high speeds on the motorway, at high engine speeds over prolonged periods of time and when driving uphill, especially if the vehicle is fully loaded or towing a trailer.

Since 2018, VW has been using only SCR technology on models with diesel engines. Earlier, NOx adsorbers rather than SCR were used on smaller size engines, including many models involved in the diesel emission scandal.

Dual SCR configurations with an added close-coupled SCR catalyst-to address cold start/low temperature NOx emissions-are being considered for future heavy-duty diesel engines, both in North America and in the European market.
Organism Font Automotive tire Auto part Fashion accessory
 

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#151 ·

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