[taibanl]

Gentlemen,

As of late it seems that many of you are on a complete emission system delete craze. The idea of this thread is to open up for discussion each particular emissions control method. That is to say:

• Exhaust Gas Recirculation
• SCR (urea) injection
• DPF

In my personal opinion, I find that only the EGR is problematic in this vehicle (as the strongly suspected source of the CBU problems.

As for DPF and urea, these systems are in pervasive use in the diesel world, without incident.

Urea/SCR seems to be a pretty damn well thought out process and for which we pay very little penalty (other than systems complexity-some have had faulty metering valves or leaky tanks, etc).

Originally Posted by [URL="Wikipedia"

http://en.wikipedia.org/wiki/Diesel_exhaust_fluid[/URL]]
Within the SCR catalyst, the NOx are catalytically reduced by the ammonia (NH3) into water (H2O) and nitrogen (N2), which are both harmless; and these are then released through the exhaust

The DPF is a harder case, as it does create some back pressure on the exhaust. I'm sure TDIWyse has posted some A/B comparison but that eludes me at present. In any case the DPF is a small price to pay for a pretty important emissions control. (Diesel Particulate Matter, in particular, is of a very dangerous size to the human lung, not quite asbestos damaging but it does present a unique hazard in that it can be absorbed by the lung).

Thus DPF may be a small performance penalty to pay, but I hear many posters cursing it, not for the performance penalty, but instead for reliability. I haven't actually heard of any DPF issues (save for one which was melted by high alcohol content meth injection). So why is everyone cursing them?


EGR of course is the bane of all of our existence.

Thoughts?

[135i_vs_]

I would add the crankcase ventilation system also to this list.
N54 are direct injection engines with no EGR, however they suffer from carbon build up. Common item, the crankcase ventilation system.

[temporaptor]

My DPF failed at 42,000 miles and my 335d is 100% stock.
We will see how long this one lasts......

[TDIwyse]

Originally Posted by taibanl

Gentlemen,

As of late it seems that many of you are on a complete emission system delete craze. The idea of this thread is to open up for discussion each particular emissions control method. That is to say:

• Exhaust Gas Recirculation
• SCR (urea) injection
• DPF

In my personal opinion, I find that only the EGR is problematic in this vehicle (as the strongly suspected source of the CBU problems.

As for DPF and urea, these systems are in pervasive use in the diesel world, without incident.

Urea/SCR seems to be a pretty damn well thought out process and for which we pay very little penalty (other than systems complexity-some have had faulty metering valves or leaky tanks, etc).



The DPF is a harder case, as it does create some back pressure on the exhaust. I'm sure TDIWyse has posted some A/B comparison but that eludes me at present. In any case the DPF is a small price to pay for a pretty important emissions control. (Diesel Particulate Matter, in particular, is of a very dangerous size to the human lung, not quite asbestos damaging but it does present a unique hazard in that it can be absorbed by the lung).

Thus DPF may be a small performance penalty to pay, but I hear many posters cursing it, not for the performance penalty, but instead for reliability. I haven't actually heard of any DPF issues (save for one which was melted by high alcohol content meth injection). So why is everyone cursing them?


EGR of course is the bane of all of our existence.

Thoughts?

This is a fascinating area that involves much more than science and cause/effect analysis behind the present regulations. I'm still learning/researching many aspects myself and would look forward to a thoughtful, science based discussion on the issues. I'd also encourage everyone interested in this area to look up and read posts by "wxman" on other diesel sites like bimmerfest and tdiclub. His understanding and knowledge in this area is supreme.

Some things I'll contribute which I've already posted elsewhere. Suffice to say I'm not a believer that much of the recent regulations, especially the DPF (see further down for one of the few studies that compare direct health impacts on DPF vs non DPF equipped vehicle), is a good compromise. Good grief, most of the particulate emissions in the air does not even come from the tail pipe anymore, and further reduction in that area is having diminishing return on helping the bigger picture. And what the DPF does do is reduce the size of the particles into the range that easily penetrates every cell of our bodies.

http://www.sciencedirect.com/science...21850210000960


There was a very large increase of volatile particles between 5 and 10 nm, and these volatile particles were generated during all of the observed regeneration events. It appears that the particle number instruments that use the PMP methodology do not capture the PM mass increase during DPF regeneration; however, for one regeneration event there was an apparent large increase in solid particles below the PMP size limit. The PM mass increase associated with regeneration appears to be due to semi-volatile particles collected on filters. During the testing, the regeneration events exhibited considerable variations in the time for regeneration as well as the amount of PM emissions. From this investigation, several questions have been posed concerning the emission of very small (<20 nm) volatile and solid particles during DPF regeneration that need further investigation.

http://www1.eere.energy.gov/vehicles...er09_dwyer.pdf

(see slide 4 in particular showing the DPF vs no DPF particulate curve and how the DPF moves radically more particulates into the nano particle range)

Since the smaller particles are more easily absorbed into organisms and, according to many studies (for example: http://www.meca.org/resources/MECA_U...0713_Final.pdf), have much more concerning (to me anyway) health implications, is it an obvious health advantage to add the complexity, cost, maintenance, increased fuel consumption, etc. to use this technology on highly efficient diesel vehicles?

Especially considering how much more particulate emissions sources there are ...


http://www.unece.org/fileadmin/DAM/t...RPE-65-20e.pdf

After thorough research of the air at highway with moderate traffic, the researchers found between 3,800 and 6,900 tyre particles per cubic meter of air while more the 58% of them are under 10 microns in size and therefore are able to penetrate into human lungs causing bronchial asthma, allergic reactions, as a result of skin and mucosa contact–rhinitis,conjunctivitis and urticaria.
According to the research carried out in Moscow [2] the core pollutant of the city air (up to 60% of hazardous matter) is the rubber of
automobile tyre used up in a small dust.
As shown in the above analysis, tyre dust emissions due to tyre protector wear (in g/km) significantly (by 6 - 7 times) exceeds emissions of particulate matters with exhaust gases of passenger car engines.


http://ec.europa.eu/transport/roadsa...culates_d8.pdf

The PM generated by road transport activity can be categorised according to its mode of formation. It is
generally assumed that fuel combustion is the primary mechanism by which particles are formed, and a
considerable body of research on vehicle exhaust particulate emissions has been compiled. However, there are
a number of other processes, involving mechanical abrasion and corrosion, which can also result in PM being
released directly to the atmosphere. These processes include:
(i) Tyre wear
(ii) Brake wear
(iii) Clutch wear
(iv) Road surface wear
(v) Corrosion of chassis, bodywork, and other vehicle components
(vi) Corrosion of street furniture, signs, crash barriers and fencing

And there's some studies showing more health impact due to having the DPF on than with it off.

http://toxsci.oxfordjournals.org/con...ft162.abstract

Rather than reducing toxicity, +DPF exhaust resulted in heightened injury and inflammation, consistent with the 4-fold increase in NO2 concentration. The ratio of bigET-1 to ET-1 was similarly elevated after −DPF and +DPF exhaust exposures. Endothelial dysfunction, thus, appeared related to particle number deposited, rather than particle mass or NO2 concentration. The potential benefits of particulate matter reduction using a catalyzed DPF may be confounded by increase in NO2 emission and release of reactive ultrafine particles.

And regarding NOx.

http://www.sciencedaily.com/releases...1030100022.htm

According to a new paper by Ott and Pickering in the Journal of Geophysical Research, each flash of lightning on average in the several mid-latitude and subtropical thunderstorms studied turned 7 kilograms (15.4 pounds) of nitrogen into chemically reactive NOx. "In other words, you could drive a new car across the United States more than 50 times and still produce less than half as much NOx as an average lightning flash," Ott estimated. The results were published July.

An old phrase comes to mind: http://en.wikipedia.org/wiki/Jumping..._into_the_fire

[F32Fleet]

Wasn't that "nanoparticle" event the result of just one of many tests? Also do we know how that test differed since it seemed to be a one off event? Compared to concentrations in ambient air how does this event compare?

[TDIwyse]

Originally Posted by Socom

Wasn't that "nanoparticle" event the result of just one of many tests? Also do we know how that test differed since it seemed to be a one off event? Compared to concentrations in ambient air how does this event compare?

Good question, but the test (http://www.sciencedirect.com/science...21850210000960), and many others, show the following is true: "There was a very large increase of volatile particles between 5 and 10 nm, and these volatile particles were generated during all of the observed regeneration events. It appears that the particle number instruments that use the PMP methodology do not capture the PM mass increase during DPF regeneration".

It seems to me based on the scientific literature I've read that it was apparent the investigators felt the "measurable" particulate emissions that lead the to the DPF regulations were "not good" ... but they didn't really understand what the emissions of the DPF were doing because their tests at the time couldn't measure the smaller nanoparticles... And the smaller ultrafine/nanoparticles are VERY bad because they easily pass through the lungs and into our cells as opposed to being stopped in our throats/lungs. This is not in itself a good thing, but ... once them nanoparticles are able to pass into our cells they pass through every barrier in our bodies (including blood/brain barrier) and cause DNA/mutagenic effects... I'd rather rely on the generations of human exposure to similar sized naturally occurring particles (forest fires, camp fires, dirt/dust, errosion, etc.) that our bodies have adapted to to filter particles from our throats/lungs than newly formed nanoparticles we have no natural defenses for...

Also, the real world impacts of pre DPF diesel emissions are, based on many real world studies, not any worse than gasoline engines that are not strapped with DPF's.

http://www.iea-amf.org/app/webroot/f...ex_42-2011.pdf

Exhaust Lung Cancer Studies
•Human workplace studies show small increase in lung cancer, but no exposure-response demonstrated – Same small increase seen before dieselization of trucks
•Miners, who have highest DE exposures show no increase in lung cancer
•Lung cancer not found in mice or hamsters and only at very high “lung overload”exposures in rats
IEA AMF Annex XLII /′11 13
•Thus, there is little evidence that DE causes lung cancer at occupational or environmental exposures
Hesterberg et al. Critical Rewiews in Toxicology 36:727-726, 2006

[taibanl]

Argh - I just typed a really long response and bimmerpost logged me out in the middle so it didn't post! I'm not going to repeat it unfortunately.

Overally the articles seem to stop short of a true conclusion as to the wisdom of DPF. Interestingly B100 may be the worst case for generating nano-particles.

Everything is situation dependent as well. How does a particular mfr.'s system work as compared to these studies? Does a SCR injection (with h2o byproduct) have any effect in helping to 'capture' nano-particles?

Overally I'm still inclined to think DPF > non-DPF but the science is interesting. Certainly the ratio of nano-particles to overall soot changes. What happens after the various exhaust cocktails leave the tailpipe is what really matters (which is more likely to hang around in the air, or settle out, or form smog, etc).

Thanks for great info TDI!

[Chief Orman]

This is a great issue to raise. IMO THE ISSUE to raise. Given the amount of thoughtful input that has been written on this forum, I begin to wonder how many lives have been destroyed by the 355d. TDI you have made more truly helpful posts on this forum than anyone. Thank you. I assume you have not seen your family for a couple of years given the length of the posts you provide on a consistent basis. Does it snow 11.5 months of the year where you live? Axel have filed the paperwork to formally adopt your mechanic yet? Cripes.

The sheer tonnage of man hours that has gone into trying to modify the emissions system on this car could sink a battleship. Here is my two cents on the whole, basically unsuccessful, effort.

- Piggyback or tune - worth it. Cheap, simple and it gets results. Axel swears by Renntech. Jarek's spider seems like the future to me...why not leverage the internet that Al Gore invented?

- DPF delete - not worth it and get meth to reduce the EGTs if you are worried about frying the DPF. I think some people, myself included, are bugged by having anything in between combustion and the tail pipe. Bang for buck does not add up.

- SCR, urea, exhaust delete - you need to have your head examined. The number of sensors involved, half baked solutions, faulty downpipes and the fact that getting the DPF out is like trying to deliver a baby wearing two oven mits while trapped in a cave. This is all a bridge too far for me. Getting rid of the urea system is just nutty. Does anyone else pickup on the secret fantasy to fill the urea tank with meth, beer or egg nog? By the way, I did not need the post where I found out that my mufflers basically consist of two small, damp throw pillows encased in sheet metal...too much information. Sort of like finding out your hot date has those underwear that have a fake rubber butt sewn into the lining.

- air scoops - two scoops of utter and complete crap...unless you can get them installed by the Easter bunny. I mean really.

- EGR plate - worth it.

- Meth - worth it even though most of us would not keep a big jug of fluid in our trunk if we could help it. Oh yeah, the empty urea tank fantasy again. Meth also has the benefit of keeping the intake clean.

- Wagner IC - kinda worth it. I am not a big fan of mods that you can't feel until you hit 60 mph.

- Transmission remap - this is what we need more than anything else. The ZF is a great transmission with an appallingly bad map. Hasn't Hanz or Franz somewhere in Germany figured this one out? Can't we pay someone to do this for us? I'd kick in real money in a heart beat. Alpina? I have seen the posts but surely they have an engineer with a gambling problem who needs to moonlight. This would transform the car.

Owning a 335d is sort of like doing a cost benefit analysis on having kids...it never pencils out but you do it any way. This car is one big fat wonderful money pit and less is more when it comes to mods.