FAQ: Diesel engines and DPF

Frequently Asked Questions
PeterL
Posts: 1118
Joined: Mon Mar 24, 2014 12:46 pm

Post by PeterL »

Mine is much the same story with a daily commute of 3 miles each way and similar journey's around the city during the day. I might do a couple of meetings a month perhaps 20+ miles each way sometimes a bit more. Absolutely no problems in 8,500 and still showing a service due at 15k. As I've said before this thread and others like it have scared the **** out of me! Every car I've had over the past 25 years has been a diesel including a BMW 300d Touring without issue as far as this subject is concerned.
Tekna CVT 1.6 Magnetic Red - born 4/4/14 P/X 25/10/2015 for £19k with 12,000 on the clock - great car but time to change. No problems whatsoever in those 18 month's.

teknaken
Posts: 134
Joined: Thu Feb 20, 2014 2:32 pm

Post by teknaken »

First I was worried that my CVT might develop a fault, then I became worried about the DPF. In more than 50 years of driving, and having owned a number of new cars, never before have I felt so tense whilst driving. Mine hasn't even developed the slightest rattle but I still find it difficult to totally relax waiting for something to happen.I'm sorry to have to say that right now I feel a twinge of regret at having joined the forums. If I hadn't I would have been enjoying comfortable and relaxed motoring in total ignorance of possible shortcomings.Having said that the forums are a mine of information and I do realise that a lot of contributors just use the forums to whinge.I'm not having a dig at anyone nor at the forums. In my case ignorance would have been bliss.I hope that it can be understood where I am coming from and I wonder if anyone feels the same.Now I am here I will be sticking around.
2019 1.3 Tekna Dig-T 160 (Automatic)
2014 1.6 dCi Tekna CVT Bronze Metallic - delivered 9/7/14
duncho
Posts: 1672
Joined: Sun Mar 23, 2014 9:45 pm
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Post by duncho »

[quote="teknaken"]
I'm sorry to have to say that right now I feel a twinge of regret at having joined the forums.A  If I hadn't I would have been enjoying comfortable and relaxed motoring in total ignorance of possible shortcomings.
Having said that the forums are a mine of information and I do realise that a lot of contributors just use the forums to whinge.
[/QUOTE]

You have nothing to worry about. Whether you joined and read posts on any forum, will not influence your car in any way. To calm you down, DPF regeneration has been improved in a way to guarantee its succesful regeneration which was set as priority nr. 1 compare to previous QQ generation. Your driving style (frequent short journeys) may only affect engine oil life time (oil change interval). Don't worry be happy :)
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teknaken
Posts: 134
Joined: Thu Feb 20, 2014 2:32 pm

Post by teknaken »

Thanks Duncho.
2019 1.3 Tekna Dig-T 160 (Automatic)
2014 1.6 dCi Tekna CVT Bronze Metallic - delivered 9/7/14
Rob_S
Posts: 143
Joined: Fri Mar 07, 2014 1:00 pm

Post by Rob_S »

[quote="SplanK"]
I have updated the 2nd post. Would appreciate a re-read to ensure no errors have been made. Hopefully it reads more "positive" and informative compared to the previous bullet points :)[/QUOTE]
"The exact parameters of when DPF regeneration is allowed to start, or how it handles interruption/town driving currently remains unclear." For K9K, from the posting earlier: - --REGENERATIONThe purpose of regeneration is to burn the particulates accumulated in the filter. In presence of oxygen, the particulates combustion regeneration occurs naturally when the temperature of exhaust gases exceeds 570A°C (1058A°F). In urban driving conditions, the engine barely reaches high temperature, and the exhaust gas temperature consequently varies between 150A°C (302A°F) and 200A°C (392A°F). Therefore, it is necessary the DPF (Diesel Particulate Filter) regeneration system, which does not adversely affect the driving comfort in any driving condition. A differential pressure sensor detects filter load status (particulate mass) and triggers the regeneration operation. This takes place by means of a controlled combustion that raises the exhaust gas temperature up between 550A°C (1022A°F) and 650A°C (1202A°F) at the filter intake. Regeneration is continuously executed according to the following: Regarding driving conditions:" Vehicle speed" Ambient pressure" Temperature upstream DPF" Engine coolant temperature--
Now 1.3 petrol Tekna + Gunmetal (Oct-2022)
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Was 1.5dci Acenta Premium Magnetic Red (March 2014)
Deleted User 759

Post by Deleted User 759 »

It does indeed. Seems as though the engine is able to turn on "thermoplungers" which increases engine load, whilst heating up engine coolant. This part suggests that there are 2 sets of injections. One in the combustion chamber and one in the exhaust manifold:[quote"]]Regulation of the exhaust gas temperature before DPF is needed to complete a secure regeneration. This strategy uses both exhaust line injectors and late post injections (fuel injectors).[/quote"]] One thing I have just found in the manual which throws a small spanner in the works :[quote"]]Oil change is required, depending on service regeneration procedure. Because fuel mixes with engine oil during service regeneration. The mixture does not occur during the regeneration which is automatically performed under normal operation.[/quote"]] hhmmmm!
Deleted User 1571

Post by Deleted User 1571 »

Here is an important quote from the linked document for the K9K. This is for a forced regeneration by the dealer.CAUTION: H Oil change is required, depending on service regeneration procedure. Because fuel mixes with engine oil during service regeneration. The mixture does not occur during the regeneration which is automatically performed under normal operation.
Deleted User 1571

Post by Deleted User 1571 »

Here's another snippet. I've used bold text for the most interesting facts. The last sentence in bold seems to suggest that there is a combination of late post combustion injection in the cylinder plus an exhaust injector, which would be the fifth injector.REGENERATIONThe purpose of regeneration is to burn the particulates accumulated in the filter. In presence of oxygen, the particulates combustion regeneration occurs naturally when the temperature of exhaust gases exceeds 570A°C (1058A°F). In urban driving conditions, the engine barely reaches high temperature, and the exhaust gas tem- perature consequently varies between 150A°C (302A°F) and 200A°C (392A°F). Therefore, it is necessary the DPF (Diesel Particulate Filter) regeneration system, which does not adversely affect the driving comfort in any driv- ing condition.A differential pressure sensor detects filter load status (particulate mass) and triggers the regeneration opera- tion. This takes place by means of a controlled combustion that raises the exhaust gas temperature up between 550A°C (1022A°F) and 650A°C (1202A°F) at the filter intake.Regeneration is continuously executed according to the following:Regarding driving conditions:" Vehicle speed" Ambient pressure" Temperature upstream DPF " Engine coolant temperatureDPF charging level criteria:" Soot mass [(computed using DPF charging curves (exhaust gas flow according to differential pressure)"]] " Simulated soot mass [computed using mapped soot mass emission speed (g/s)"]]" Driven distance since last successful regeneration" Regeneration failures counterECM activates many engine management function to ensure good regeneration efficiency:Fuel system: A specific injection pattern using post injections is activated.Air system: EGR volume control valve is closed and throttle valve (intake) is used to control engine air flow.In regeneration mode, other boost pressure set points are defined.Auxiliary functions: These functions (e.g. thermoplunger, etc.) are used to increase engine load. At the same time, two specific exhaust gas temperature controllers are sequentially activated:Upstream turbine temperature control: As soon as a DPF regeneration is requested, the regulation is acti-vated in order to obtain the highest safe upstream turbine temperature for any engine operating point andwithout turbine damage risk (over temperature).Upstream DPF temperature control: This regulation is activated to heat DPF and to control its regeneration.REGULATION OF TEMPERATURE BEFORE DPFRegulation of the exhaust gas temperature before DPF is needed to complete a secure regeneration. Thisstrategy uses both exhaust line injectors and late post injections.ECM computes the fuel mass flow injected by injectors (post injection) according to several parameters: " Exhaust line temperature before DPF" Atmospheric pressure" Intake air temperature" Differential pressure of the DPF" Minimum level of fuel" Engine speed" Engine torque
Quacker2015-02-13 15:58:42
Deleted User 1571

Post by Deleted User 1571 »

There is no simple answer. Read the document for an explanation, the most simple and non-technical of which I copied in the post above.Essentially, there is a restriction valve in the exhaust which loads and pressurises the system before it, including the DPF itself, then the injection volume and timing is altered to be later and an extra [sixth"]] late squirt of fuel is injected, all of which raises the temperature as indicated in that copied text. It does mention a fifth injector in the exhaust as well, but I have been unable to find that in the schematics or in any further text, although I have only skimmed through it all.Cost? Yes, there is a cost to buy this gubbins, a running cost, and ultimately a probable repair and maintenance cost that is best expressed as an average of the purchase price in the absence of long term experience. Once out of warranty, the owner picks up the bill, whether for forced regenerations, complete new DPF units [they have a finite life even when 100% successfully regenerating automatically in optimum conditions"]], diagnosis, sensor and actuator repairs and replacements and so on and so forth.These engines, of all brands, are no longer suited to long term, low annual mileage private use by the budget conscious. They are too fussy and temperamental and the potential repair costs are far too high. Fine for businesses who run them intensively for high miles in a relatively short period of time but not suitable for the three mile to the shops and back three times a week. These people should, without a doubt, avoid the current generation, and probably future generations of diesel engines. Some may favour petrol engines but the three mile there and back people would do well to consider pure electric vehicles. Nissan do electric cars where you pay an annual rent for the batteries, which gives a known long term running cost.
Kentishman
Posts: 237
Joined: Tue Jun 10, 2014 11:54 am

Post by Kentishman »

I would like to thank all those knowledgable people on here for the benefit of that knowledge. As someone else has said it is a two edged sword as the less knowledgable of us have the fear of God put into them that we are going to break down tommorrow
Could I justt comment on one view. The average motorist, like me, was not aware of the fact that apparently modern diesels are not suitable for urban driving. I used to drive a discovery diesel which never gave me any issues, so when I changed back from my prius to a new diesel, which I had to have for the automatic, ii asummed newer models would be even better. The dpf issue was not raised by salesman, was not in the general media, nor in any of the magazine articles I looked at. This experience is mirrored by all the people I have spoken to at a local club.
I repeat I am grateful for or the benefit of anyone's knowledge but am concerned that low mileage people are somehow how stupid for buying a diesel and any problems are their fault. This is not a generally known issue
Tekna 1.6 CVT Nightshade
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