DPF removal? Better think again!

[Mandrake]

Good point Ben. I paid £480 for a Xantia V6 that had only done 65k miles and have done 10k miles on it in the coming up on 2 years that I've had it and have probably only spent about £600-700 on catch up maintenance including a full set of spheres...so total cost of ownership has been very low.

(That will go up a bit soon when it gets a set of tyres, but all cars wear tyres...)

Petrol costs me a bit but the car was a real find for the price and is a joy to drive.

[Deanxm]

Mine regens just fine, commute 9 miles each way, DPF stays clean as a whistle, trouble is its not very good at doing it without filling the sump with diesel, it is getting better with age but not what i would expect.

I think top speed of a car is very important, a car that will only do 90 will be a dog to drive on the motorway, a car that is able to hit 155 is going to purr at 70 so i kind of view the top speed figures more like a guage of refinement.

D

[spider]

I think one thing that is (was?) overlooked, unless it has changed the early DPF's at least were meant to be replaced occasionally too. Owners were not very happy at the 700+ odd in addition to the large service cost for this.

[spider]

One thing I'd like to know (I've not seen it but I've not really looked for it) during a 'regen' either on the road or forced, what is the actual pollution output and what is its content while its um 'cleaning' the DPF ?

Perverse logic might suggest that the DPF is simply 'storing' the 'nasties' then releasing them later, although I realise that's **not** the case given the chemical process of the Eolys fluid, although that's not very pleasant stuff...

Genuine question from someone who is curious...

[Deanxm]

Its a good question and what i do know is that the DPF is a store for hydrocarbon based particulate matter and the eolys fluid (although it very tricky trying to find out what it actually is or does) helps complete the burning off of these particles all the time but the car needs to run with elevated exhaust temps to work efficiently, if you potter everywhere it just doesnt work and eventially the DPF cloggs.
I have heard it said that the Eolys fluid lowers the temperature at which these particulates burn and while a significant amount is ejected from the exhaust an aweful lot more is burnt and it is evident the net result is lower particulate emissions.

Adblu i was suprised to learn is just Urine and water which is injected directly into the exhaust of comercial vehicles purely to lower NoX emmissions, ive always wondered why the two systems cannot be combined to reduce particulate AND NoX.

The newer system with which my truck is equiped is slightly more simple, it adds a second dose of fuel on or near the exhaust stroke to create a burn in the exhaust and raise exhaust gas temps and so achieve the same burn in the DPF as an eolys system would but without having to run the engine hard which is done under certain conditions, this does make the truck drop a bit of power and economy (10mpg reduction) during a regen and on many manufacturers vehicles results in oil contamination with fuel but my truck will regen on the 8 mile drive home through 30-40mph limits at 2k rpm, i dont think the eolys based system can do this. This new type system is the only type that does a regen where the engine ecu actually says "lets do a regen" and alters injection maps to achieve glowing mainfold temps rather just waiting for you to get the hammer down (which may never happen.

So far as i can see the Eolys based systems do not "regen" they will make eolys present in the fuel at all times and when you dive the car in a way that creates high egt's the particulates will burn, no heavy right foot = no high egt = no burn. A forced regen looks like the ecu just props the throttle open for as long as it takes to see below threshold pressure upstream of the DPF.

Correct me if im wrong but thats the way i understand it.

D

[RichardW]

Correct me if im wrong but thats the way i understand it.

D

OK

The DPF collects the soot particles - regenerating it causes these to burn off which produces CO2. The tail pipe of a DPF car should be clean, so no 'nasties' are released - although there is a higher CO2 emissions for the time it is regenning. There's usually plenty of oxygen available in a diesel exhaust, but I guess it's possible that some CO is made.

The Eoyls lower the ignition temperature of the soot, making it easier to re-gen. It's possible for a eoyls system to passive regen on a decent run if it gets hot enough; however, forced regen is more common. To do this it does alter the map, and on most cars bypasses the intercooler, and possibly does some post injection to get the exhaust temp high enough to light off the DPF. Non-eoyls systems require a higher temperaure, which is why they are prone to ending up with diesel in the sump, as much more post injection is required.

Oddly, the latest PSA systems with adblue don't use Eoyls, But I don't know if this leads to a tendency to overfill the sump.

[Deanxm]

Smartass

Thats interesting and makes a lot of sense, the HDI system is more advnced than i thought then and certainly better than the newer additive free solution in fact.

D

[GiveMeABreak]

Smartass
Thats interesting and makes a lot of sense, the HDI system is more advnced than i thought then and certainly better than the newer additive free solution in fact.
D

I think I've put a link previously on the principle, but here it is again from PSA:
http://www.psa-peugeot-citroen.com/en/f ... ate-filter

[white exec]

Sorry, but I can't excited about DPF or NOx systems which currently rely on what is described above.

Do wonder, too, about the 'whole life' emissions of these systems, i.e. total output resulting from normal driving and regeneration/cleaning.

Wonder whether the car manufacturers have kept a bit quiet about the purging cycles, preferring to concentrate on the cleaner normal driving part of usage. Would they do such a thing?

Have just read a few articles about Mazda's Skyactiv-D engine design. Looks like a good route, and without all the clutter and compromise of DPF and NOx systems. Haven't managed to find any long-term test reports on the engine's durability and emissions, though.

Roll on all-electrics, and we can forget all of this.

[Paul-R]

Do wonder, too, about the 'whole life' emissions of these systems, i.e. total output resulting from normal driving and regeneration/cleaning.

Me too. I remember some ten or fifteen years ago that it was reported that diesel engines had higher NOx emissions than petrol when the engine was new but that, because a petrol engine wears quicker than a diesel one, over the whole lifetime of an engine a petrol one emitted more NOx than a diesel.

I wonder whether that is still true and, if so, why aren't petrol engines being chased to fit AdBlue systems as well.

[Paul-R]

Oddly, the latest PSA systems with adblue don't use Eoyls, But I don't know if this leads to a tendency to overfill the sump.

Are you sure about this? About half way down the page at the PSA site implies that both are fitted.

How does the Blue HDi exhaust line work?

The Blue HDi exhaust line comprises two key subsystems:
•A PSA Peugeot Citroën additive Diesel Particulate Filter which drastically reduces the particulate emissions by 99.9% in terms of number, whatever their size and driving conditions.
•An SCR (Selective Catalytic Reduction) system upstream of the aDPF which reduces till 90% of the nitrogen oxides (NOx) produced by the engine.

http://www.psa-peugeot-citroen.com/en/f ... -reduction

[GiveMeABreak]

The new Blue HDi systems use the Adblue as well as the Eolys for the DPF part (the Particulates removal operation) and the SCR for the NOx reductions, as far as I can see.
Edited to clarify both types are used.

[Paul-R]

I certainly don't read it that way. The description in the text is a bit nebulous about the DPF additive but the YouTube video linked to in the first bullet point states that the additive is in-tank.

Besides I can't see how, chemically, AdBlue would affect the combustion temperature in the DPF as it is not a catalyst as such. In fact as it's urea, which is an organic compound, it would surely not make it through the ceramic NOx reduction substrate in any meaningful quantity.

[GiveMeABreak]

The Adblue is in a separate tank though - on some vehicles it is filled via the boot and others via the fuel filler Paul.

Filler in Fuel Cap

Filler Tank - Boot

[Paul-R]

That doesn't mean that there isn't a tank elsewhere for the Eolys though. Just that AdBlue needs topping up more often.