Diesel DPF Concerns

All Jaguar E-Pace related discussions
rriggs
Posts: 20
Joined: Mon Aug 26, 2019 2:48 pm

Re: Diesel DPF Concerns

Post by rriggs » Thu Aug 29, 2019 6:26 pm

Active regen takes 10-15 mins

I suspect the manufacturers don’t put a light because people would complain if their car does it too often (or what they consider to be too often)
D150 S R-Dynamic - Caldera Red - July 2019


revoke
Posts: 18
Joined: Mon Aug 19, 2019 8:55 am

Re: Diesel DPF Concerns

Post by revoke » Fri Sep 06, 2019 8:31 pm

ctoneman wrote:
Thu Aug 29, 2019 7:53 am

Like others commenting, I have not been aware of the regeneration actually occurring on my D180 and have never had a problem with the DPF in 14k miles

How long does the regeneration process last each time ? Does it vary with speed ?

If the problem can occur if the process is interrupted by shutting off the engine, why then can’t we have the option of not shutting off the engine while a “ regeneration ongoing light “ is illuminated on the dashboard.

I suspect it is not that simple or logical 😀
Because it wouldn't achieve much for the majority of owners, I think is the answer. Engineering know that the main problem is oil dilution during normal driving, something that happens independently of the very short journeys and slow driving associated with DPF blocking. On an aged stress test of a 17MY D180 DS which was supposed to be run constantly to 100,000 miles over three months the test had to be stopped 9 times due to excessive oil dilution that threatened to wreck the test engine. The test could only be completed by changing the oil every 9,000 miles. This engine never stopped and yet it still experienced high dilution !

From this data and other scientific papers dealing with "oil dilution due to post injection" it's known that driving the car, not stopping it, is the real cause of the dilution. There is, it has to be admitted, a small increase in post injection (hence more dilution) when a regen is stopped half-way through due to the additional warm up period required. Say a long-distance driver's car needs a 5 minute warm up followed by a 20 minute burn (a typical scenario). That's 25 minutes of post injection in total, of which 20 minutes is the actual soot burning regeneration. If the car stops when the soot load is only 50% burnt, the car will complete the job next time, provided the journey is long enough. The resumed burn will also need 5 minutes to warm up the DPF to 580 deg C so the total time to regenerate the DPF in this case is 30 minutes instead of 25. It's an increase of 20% dilution and represents a reduction in service mileage of 17%.

The real problem that arises with repeatedly preventing a regen from completing is DPF blockage. If you read the JLR letter to dealers it talks about these two effects separately and makes this distinction: ALL cars will suffer dilution. Some fraction of cars will additionally get DPF clogging. They wrote this after the stress testing and the inferences to be drawn are clear.

Regarding the 10-15 minute claim. This is for an ideal installation with a close coupled DPF like on the XE or FPace. The 70 cm of pipe on the D8 acts like a heat sink and that's the second issue: the actual burns have to be longer, as well as being more frequent. A JLR powertrain engineer from Gaydon provided this information 2 months after the SCN first appeared.


rriggs
Posts: 20
Joined: Mon Aug 26, 2019 2:48 pm

Re: Diesel DPF Concerns

Post by rriggs » Sat Sep 07, 2019 7:31 am

revoke wrote:
Fri Sep 06, 2019 8:31 pm
If you read the JLR letter to dealers it talks about these two effects separately and makes this distinction: ALL cars will suffer dilution. Some fraction of cars will additionally get DPF clogging. They wrote this after the stress testing and the inferences to be drawn are clear.

Regarding the 10-15 minute claim. This is for an ideal installation with a close coupled DPF like on the XE or FPace. The 70 cm of pipe on the D8 acts like a heat sink and that's the second issue: the actual burns have to be longer, as well as being more frequent. A JLR powertrain engineer from Gaydon provided this information 2 months after the SCN first appeared.
Just read the JLR letter again and I can’t see where it says ALL cars will be affected by dilution. It quite clearly says that cars that do not complete the regen will be affected but is specific about that.

Each time a regen happens and i notice it, I would say that 15 minutes is about right. On my regular commute it does it begins after about 10 minutes driving. It is normally complete before the end of the 30 minute journey which is therefore about 15 minutes.
D150 S R-Dynamic - Caldera Red - July 2019


revoke
Posts: 18
Joined: Mon Aug 19, 2019 8:55 am

Re: Diesel DPF Concerns

Post by revoke » Sat Sep 07, 2019 5:06 pm

You are correct, the letter to dealers does not explicitly say that "all" vehicles will suffer from dilution - nevertheless, they do. All cars that use diesel post-injection (except those fitted with a separate fifth injector) dilute the lubricating oil with diesel. What matters is the rate of accumulation of dilution, and its impact on the nominal service mileage and long-term health of the engine.

JLR set the service interval for the Jaguar XE (first JLR diesel with Ingenium) at 21,000 miles after testing showed that its close-coupled DPF enabled it to cover 21,000 miles between services while keeping dilution to a "safe" level. They set a trigger of 6.1% "estimated" diesel which is about 5% actual dilution. Here's a Jaguar XE DPF showing the flange (top right) which attaches directly to the turbo-charger outlet, the hottest part of the engine exhaust.

XE DPF.jpg

This close-coupled DPF design is used on XE/XF, Velar and F-Pace (D7a chassis) and, because of the proximity of the heat source to the DPF, it is only minimally affected by diesel dilution and 21,000 miles is usually reached before the 6.1% trigger point. Diesel dilution can still be high enough to reduce the service mileage, but nothing like the amount seen on the D8 SUVs. A Jaguar XE driven at low speed on short duration journeys might need a service at 19,000 miles but this sounds reasonable to the owner who has been told that "the nominal service interval is 21K miles but this may be shorter depending on driving style". That same reason tends to stick in the craw when being given to someone who has just seen their expected 21K service interval reduced by 70% to 6,000 miles. When JLR engineering wrote JLRP00100 explaining the problems of excessive or "higher than expected" diesel dilution on some models, the Jaguar XE was the benchmark vehicle used for comparison.

All Jaguar XE 2.0L Ingenium diesels accumulate some diesel in the oil, just like any car that uses post injection for active regeneration of its DPF. So what are the engineering "challenges" referred to in the letter to sales staff which said - and I paraphrase:
On the D8 (Evoque, DS, E-Pace). the engine and the DPF are 70 cm apart, and partially masked from one another by a bulkhead. This exhaust design will be heavily affected by Oil Dilution and DPF blockage and these issues are likely to be more common for (but not restricted to) low speed, short duration drive cycles. The impact of the distance between the heat source and the filter (DPF) can lead to failed attempts to regenerate and, as a result, so oil dilution occurs. The soot is burnt off by supplying post injected diesel to the DPF and then igniting it to burn off the soot. This process takes "around" 20 minutes. D8 vehicles which are used in a typical low-speed, low-duration drive cycles will suffer from oil dilution as a minimum but also in many cases will have blocked DPFs.
This is similar to the engineering notification sent to service departments in July 2017. Again, the words are all JLR's (when JLRP00100 appeared the E-Pace wasn't available):
The service message is being displayed early due to oil dilution caused by a higher than expected number of partial DPF regeneration cycles. The number of partial regeneration cycles is higher because the distance to complete a full regeneration is longer. This increases the probability of a given journey being interrupted compared to the same journey completed in, for example, an XE. Hardware and architectural differences between the D8 and D7a cars account for this. The amount of post injection required is much higher on Evoque/Discovery Sport which significantly increases the Fuel In Oil (FIO) contribution for each successful regeneration event. The increased post injection requirement and increased impact of interrupted regeneration on oil dilution, causes FIO to increase at a much faster rate on Land Rover models.
Behind these engineering publications lay the test results from the experiments that JLR had conducted on the Discovery Sport and Evoque to check how the D8 exhaust performed over the long term. A person on the Discovery Sport forum, almost certainly a JLR insider wrote: "I would refer you to the most recent LTT carried out at GDEC on a PTV 19MY L550 D180 which confirmed a maximum under optimum of just 9170 miles". Further on in the same thread this person remarked that all the D8 vehicles built "pre-PTA" will suffer "unavoidable fuel in oil dilution issues". I think PTV = Prototype Test Vehicle, LTT = Long-term Test(?) and GDEC = Gaydon Design & Engineering Centre.

What does 9,170 miles "maximum under optimum" mean? I'm not sure but I suspect that the best the test prototype could achieve (19MY DS) was 9,170 miles between each oil change. Presumably such long-term testing is conducted in conditions which are about as far away as it is possible to get from "low-speed, low-duration drive cycles" referred to above. It's therefore the best average that can be expected with maximum diesel dilution set at 6.1%. (with 10% dilution this rises to 15,300). There was another post on the DS forum which collated almost 100 owner reports of premature service due to diesel dilution. As the graphics below nicely illustrate, the average mileage in this population of D8 cars was just 8,300, which seems remarkably close to the figures obtained at Gaydon by JLR's long term test team. First, though, here's the DS DPF architecture for comparison with the XE. If you've got a five year old handy, ask them if they can work out where all the heat is being lost .....

Exhuast Architecture.PNG

100 users provided the raw data for these graphics: https://www.discosportforums.co.uk/viewtopic.php?f=17&t=5379&p=104505#p104505

Oil_Histogram.png

Missing Miles.png

N289 appears to be JLR's way of drawing a line under this unfortunate episode. Engineering seems to have been reduced to this: "We can't fix it so we are just going to hide it". There are some problems, though. Firstly, the oil dilution won't stop. It's going to keep rising at the same rate - it's just that post- N289 fewer owners will be aware of it. The possibility of mechanical failure highlighted by JLR will rise: we can predict 66% more engine failures due to 10% dilution. The DPF clogging won't go away either, in any case the dilution threshold was never relevant to the drivers affected by this because usually they never get that far.

What damage all of this might do to the engines in the long term is a separate discussion and that's not the point of this post. I just wanted to present some of the hard evidence pointing to diesel dilution affecting "every D8 diesel car" with an average mileage between services which is less than half what was originally advertised and which is still used as the "nominal" service interval. An increase in servicing costs on this scale is not due to "driving style".

Next time anyone says that to you at the stealership, ask them why it wouldn't have happened if you owned a Jaguar XE!


Duncann32
Posts: 76
Joined: Fri Nov 16, 2018 9:53 pm

Re: Diesel DPF Concerns

Post by Duncann32 » Sat Sep 07, 2019 7:51 pm

After reading this I wish I would have got the Jaguar XE😂
Jaguar e pace


ctoneman
Posts: 252
Joined: Fri May 18, 2018 11:39 pm

Re: Diesel DPF Concerns

Post by ctoneman » Sun Sep 08, 2019 8:28 am

After reading all this I wish I had chosen petrol 😀

Very interesting though, thank you
E-Pace S D180 AWD Auto Firenze Red


Duncann32
Posts: 76
Joined: Fri Nov 16, 2018 9:53 pm

Re: Diesel DPF Concerns

Post by Duncann32 » Sun Sep 08, 2019 11:27 am

Jaguar needs to sort a fix out for this problem
Jaguar e pace


revoke
Posts: 18
Joined: Mon Aug 19, 2019 8:55 am

Re: Diesel DPF Concerns

Post by revoke » Tue Nov 05, 2019 12:41 am

DPF/SCRF. Full guide to oil dilution and DPF blockage problem.

Read online.
[url]https://www.dropbox.com/s/d0bcrd7sve4l598/D8_Dilution_Explained.pdf?dl=0[/url]

Download.
[url]https://www.dropbox.com/s/d0bcrd7sve4l598/D8_Dilution_Explained.pdf?dl=1[/url]


bobc
Posts: 29
Joined: Wed Dec 27, 2017 1:01 pm

Re: Diesel DPF Concerns

Post by bobc » Tue Nov 05, 2019 6:23 pm

My service warning came on last week at 9200 miles after 18 months from new, dealer has just reset service warning to allow a further 5000 miles, this should take me to the scheduled service date, does this mean I will be driving on diluted oil? would Jaguar take this sort of risk to their reputation?
D180 S.


revoke
Posts: 18
Joined: Mon Aug 19, 2019 8:55 am

Re: Diesel DPF Concerns

Post by revoke » Tue Nov 05, 2019 11:38 pm

bobc wrote:
Tue Nov 05, 2019 6:23 pm
My service warning came on last week at 9200 miles after 18 months from new, dealer has just reset service warning to allow a further 5000 miles, this should take me to the scheduled service date, does this mean I will be driving on diluted oil? would Jaguar take this sort of risk to their reputation?
D180 S.
Yes. There are 3 counters governing the appearance of the "service required" alert: mileage, time and % diesel dilution. If the message appears prematurely then it is always due to excessive diesel dilution. See the guide for a fuller explanation.

Regarding the risk to reputation, when EU6 Nox limits were introduced in 2014-15, it was either this or risk prosecution for using VW-type software devices available on the Bosch EDC17 engine management unit. Many think that the diesel dilution and DPF blockage problems arose because JLR chose not to deploy diesel defeat devices with a problematic, too-long, too-cool exhaust architecture.

The oil service should be free for all 2016-2020 diesels up to 55,000 miles.

https://www.discosportforums.co.uk/viewtopic.php?f=8&t=10783&p=110569#p110569


Post Reply

Return to “Main Jaguar E-Pace chat”