Member Since: 10 Sep 2012
Location: Northampton
Posts: 1034
1. Engine management to increase exhaust temperature through late fuel injection or injection during the exhaust strokeGAP IID Pro Multi Vehicle Defender L316 2007-2015 - Discovery 3 - Discovery 4 - Discovery Sport L550 - Freelander 2 - Range Rover Evoque L538 - Range Rover L322 - Range Rover L405 - Range Rover Sport L320 - Range Rover Sport L494 Electrical Fault Diagnostics
4th Dec 2014 7:57 am
DG Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50978
Streffie is correct in that one of the drawbacks is that a very small amount of diesel will contaminate the oil however he underestimates the fact that LR have taken this into account and the ECM will tell you when the oil needs to be changed as a result. You don't have to guess with indiscriminate oil changes. 21 year LR veteran > D2 GS 2003 > D3 S 2006 > D3 HSE 2009 > D4 HSE 2013 > D4 HSE 2015 > D5 HSE 2018 > DS HSE R-Dynamic P300e 2021
4th Dec 2014 8:34 am
DiscoJake
Member Since: 23 Aug 2013
Location: Hereford
Posts: 1429
Strangely I was talking to my Indy yesterday about D4 being more reliable than D3 and he then mentioned a D4 he'd had to change engine on at 40k, only issue was it had NEVER had an oil change
Not yours was it hc76?
4th Dec 2014 11:11 am
hc76
Member Since: 02 Sep 2009
Location: Herefordshire
Posts: 105
Fortunetly not. Mine had full service history and was covered under warranty.2016 D4 Landmark - Waitomo/Ebony
2012 D4 HSE - Orkney/Almond - gone
2009 D4 XS - Buckingham/Ebony - gone
4th Dec 2014 12:44 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Streffie wrote:
Right, the reason we are seeing engines seize, is the fact that when the diesel is injected on the exhaust stroke….
Allan_T wrote:
1. Engine management to increase exhaust temperature through late fuel injection or injection during the exhaust stroke
DG wrote:
Streffie is correct in that one of the drawbacks is that a very small amount of diesel will contaminate the oil...
Are we sure about this idea that the D4 uses fuel injected on the exhaust stroke rather than just late injection?
I've not got access to a scope at the moment (will do shortly) but I do not recall ever seeing a pulse on the exhaust stroke. The waveform appears to have 5 clear points, 2 prior to main injection, the main injection and 2 after the main pulse. These final 2 late-injection pulses on the power stroke are part of the emissions strategy; the first to reduce particulate matter and the final pulse to regulate EGT (in cooperation with the EGR and turbo) for DPF management.
Happy to bow to the more knowledgeable but I am still struggling with this one, although this could be because my memory is rubbish. When I get a scope I will post pictures of the injection waveform; if anyone else has a scope and a D4 to hand then a set of pictures would be great.
Robbie - confused of this parish.Land Rover - Turning Drivers into Mechanics Since 1948
Last edited by Robbie on 4th Dec 2014 6:50 pm. Edited 1 time in total
4th Dec 2014 6:27 pm
DG Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50978
Well I can't comment on your waveform pulse technical thingy ....but I can help possibly with this:
Quote:
It is determined by the DPF software monitoring the signals from the two DPF temperature sensors to establish the temperature of the DPF. Depending on the DPF temperature, the DPF software requests the ECM (engine control module) to perform either one or two post-injections of fuel:
The first post-injection of fuel retards combustion inside the cylinder which increases the temperature of the exhaust gas.
The second post-injection of fuel is injected late in the power stroke cycle. The fuel partly combusts in the cylinder, but some unburnt fuel also passes into the exhaust where it creates an exothermic event within the catalytic converter, further increasing the temperature of the DPF.
...and as for adhoc oil changes ...here is clarification that the systems are already on the case to take away the guesswork
Quote:
Diesel Particulate Filter Side Effects
The following section details some side effects caused by the active regeneration process.
Engine Oil Dilution
Engine oil dilution can occur due to small amounts of fuel entering the engine crankcase during the post-injection phases. This has made it necessary to introduce a calculation based on driving style to reduce oil service intervals if necessary. The driver is alerted to the oil service by a message in the instrument cluster.
The DPF software monitors the driving style and the frequency of the active regeneration and duration. Using this information a calculation can be made on the engine oil dilution. When the DPF software calculates the engine oil dilution has reached a predetermined threshold (fuel being 7% of engine oil volume) a service message is displayed in the IC.
Depending on driving style, some vehicles may require an oil service before the designated interval. If a service message is displayed, the vehicle will be required have a full service and the service interval counter will be reset.
Fuel consumption
During the active regeneration process of the DPF, there will be an increase in fuel consumption.
However, because active regeneration occurs infrequently, the overall effect on fuel consumption is approximately 2%. The additional fuel used during the active regeneration process is accounted for in the instantaneous and average fuel consumption displays in the instrument cluster.
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Thanks DG, that document confirms what I thought I saw. There is no fuel injected on the exhaust stroke and that the EGT is regulated by the late pulses on the power stroke alone. The amount of unburnt fuel on a late injection of fuel on a power stroke is tiny when compared to deliberately injecting fuel on an exhaust stroke.
I'll rest easy that JLR are not doing anything stupid - oh and that I have not gone mad when scoping injectors in the past.
Where did you find that reference?
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 16 Sep 2007
Location: UK
Posts: 6019
You would have to check it during a regeneration phase on a scope and once you stop it will cancel itself.
On the Vauxhalls if you do a manual regeneration you have to change the oil as well. It is quite scary seeing the car stationary and rev upto I think 3K for 10-15 minutes. The exhaust gets very very hot and you can see the percentage of blockage reduce as it goes through the process.
4th Dec 2014 6:39 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Found a copy of the D4 injection waveform:
Click image to enlarge
It matches my observations and the document DG has quoted.
Land Rover - Turning Drivers into Mechanics Since 1948
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
