# downward trend in DPF regens



## sirbikes (Aug 17, 2012)

I think I'm seeing a downward trend in my average miles between regens. I have 75K on my vehicle. What could this mean ... DPF effectiveness waning, overfuel condition leading to more soot (I have a remap), carbon buildup? How to know?


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## F32Fleet (Jul 14, 2010)

Looks normal to me on a year over year basis. I would guess you did a bit of traveling during the holidays. 

FWIW the DPF will eventually clog up. Knowing avg speed and mpg would be helpful.


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## sirbikes (Aug 17, 2012)

I did a fair amount of traveling, yes, as well as some towing. Mostly highway miles, with some stop and go traffic mixed in. Avg speed 75mph on highway and 35 city, maybe 47 avg. MPG is fairly constant around 24 avg. Seems like it's dropping a bit recently, but too early to tell, may just be the hot 85+ deg and humid weather now.


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## mefferso (Feb 26, 2014)

Ha, and I thought I was the only crazy one that kept track of every regen. Haven't put mine in a nice looking spread sheet yet though. 

I can't really offer an answer other than agreeing possibly DPF not as effective for whatever reason or maybe a slight malfunction of the sensor that measures the flow differential before and after the DPF


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## glangford (Dec 11, 2013)

How do you get your dpf regen data? I've never sensed my 328d having one.


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## Jamolay (May 11, 2014)

Ok, I'll ask. What is a dpf regen?


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## mattebury (Feb 2, 2014)

Jamolay said:


> Ok, I'll ask. What is a dpf regen?


Oversimplified, when the DPF (Diesel Particulate Filter) gets clogged up with soot, the car will purposefully increase exhaust gas temperature to incinerate that soot and restore the filtering function of the DPF.


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## mefferso (Feb 26, 2014)

glangford said:


> How do you get your dpf regen data? I've never sensed my 328d having one.


Im sorta ocd about watching my instantaneous mpg dial and when drops about 10 mpg below normal for 10-15 miles is when its occurring.


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## Axel61 (Mar 10, 2011)

cant wait to remove the DPF my downpipe will be finished this weekend thanks to 2deerwhistlers, anyone want a downpipe contact him any X5d need to send him a DPF so he can make a prototype and make some for our x5d brothers


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## Jamolay (May 11, 2014)

Is that legal?
Sucks that you care so little a about polluting unnecessarily.


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## Axel61 (Mar 10, 2011)

Jamolay its not legal are u going to pay for future breakups on my car? No so I'm not worried about my car polluting just go over china and most of india are they regulated dont think so

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## Nadir Point (Dec 6, 2013)

Jamolay said:


> Is that legal?
> Sucks that you care so little a about polluting unnecessarily.


The amount of emissions controls necessary to meet current EPA diesel requirements constitutes an extremely disproportionate tradeoff. IOW, the cost vs. benefit of the DEF+DPF+EGR is way higher than the benefit of the small reduction in emissions they give, in terms of both the manufacturing and the maintenance costs.

And if you want to use the term "unnecessary," consider that diesel soot is not even a pollutant in the strictest sense of the word - just a mostly inert, black carbon-based particulate people don't like to look at.


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## glangford (Dec 11, 2013)

Nadir Point said:


> The amount of emissions controls necessary to meet current EPA diesel requirements constitutes an extremely disproportionate tradeoff. IOW, the cost vs. benefit of the DEF+DPF+EGR is way higher than the benefit of the small reduction in emissions they give, in terms of both the manufacturing and the maintenance costs.
> 
> And if you want to use the term "unnecessary," consider that diesel soot is not even a pollutant in the strictest sense of the word - just a mostly inert, black carbon-based particulate people don't like to look at.


The cost/benefit analysis is not the consumer's job, and it's surely not the consumer's to decide, at his will, to not comply with the mandated regulations.


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## F32Fleet (Jul 14, 2010)

Nadir Point said:


> The amount of emissions controls necessary to meet current EPA diesel requirements constitutes an extremely disproportionate tradeoff. IOW, the cost vs. benefit of the DEF+DPF+EGR is way higher than the benefit of the small reduction in emissions they give, in terms of both the manufacturing and the maintenance costs.
> 
> And if you want to use the term "unnecessary," consider that diesel soot is not even a pollutant in the strictest sense of the word - just a mostly inert, black carbon-based particulate people don't like to look at.


But NOX is.


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## Pierre Louis (Oct 23, 2011)

glangford said:


> The cost/benefit analysis is not the consumer's job, and it's surely not the consumer's to decide, at his will, to not comply with the mandated regulations.


So, uh, tell me you comply with each politically derived, bureaucrat enacted, and (cough cough) fairly applied rule and regulation in both spirit and substance?

How does it feel to always go below or at the speed limit?

Diesel exhaust from automobiles is still more strictly regulated than light trucks, while lawn mowers, old cars, etc. are allowed to pollute much more....

As do we all, we would like to comply with all regulations and laws. This in an ideal world.

PL


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## Pierre Louis (Oct 23, 2011)

BMWTurboDzl said:


> But NOX is.


To the best of my knowledge, the particular type of smog that NOx contributes to at the minuscule levels that diesels put out (although more so than gassers) affects the Los Angeles Valley the most, from where, coincidentally, come the major legislators responsible for CARB and its effects on the rest of the country. It was said that before the "settlers" came, the valley was known for its black sky from smoke caused by wood fires of Native Americans.... the valley apparently holds in a lot of smoke with surrounding mountains etc.

The NOx rules are meant originally for gasoline engines, but when all the regs are applied to reasonably de-smogged diesels (circa model year 2002 for example) diesels come out better in most other pollutants. Putting a square peg into a round hole is what the feds have done with automotive diesel emission rules. We are paying for it with our "super clean" diesels' emission equipment costs...

PL


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## MotoWPK (Oct 5, 2012)

Nadir Point said:


> And if you want to use the term "unnecessary," consider that diesel soot is not even a pollutant in the strictest sense of the word - just a mostly inert, black carbon-based particulate people don't like to look at.


A carbon based particulate that contains many complex compounds, including a number that are known carcinogens.


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## Jamolay (May 11, 2014)

Although I agree that there are costs and losses associated with emission controls, and that the individual emissions of a diesel car are somewhat small in the grand scheme if things, it is attitudes like this that are leading us to severe global problems due to overall pollution levels. We need to do what is reasonable and prudent and eliminating emission controls already in place shows a willful disregard for the planet and your fellow human beings.
I am sorry you disagree, it is sad for all of us.


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## YozhDzl (Mar 5, 2014)

Both NOx and CO are greenhouse gases. However, European regulation are more CO focused and North American are more NOx focused. That is why small diesels are not popular here. If you look at Euro 6 requirements vs LEV2 requirements, you will see a clear picture of how much more CO is allowed under LEV2 vs NOx compared to Euro 6. Probably something to do with the fact that gasoline powered cars put out much more CO and legislation is favoured to the oil industry, big three and all the truck driving crowd. Pick your poison, but I would rather drive a much more efficient diesel that I have to modify to be more reliable and as a byproduct of it, more efficient, with a bit more NOx. But my CO will still be low and my PM are slightly more elevated and will precipitate faster and will have less of a chance of causing cancer.


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## Pierre Louis (Oct 23, 2011)

Jamolay said:


> Although I agree that there are costs and losses associated with emission controls, and that the individual emissions of a diesel car are somewhat small in the grand scheme if things, it is attitudes like this that are leading us to severe global problems due to overall pollution levels. We need to do what is reasonable and prudent and eliminating emission controls already in place shows a willful disregard for the planet and your fellow human beings.
> I am sorry you disagree, it is sad for all of us.
> 
> Sent from BimmerApp mobile app


Driving a diesel in itself is an improvement over gasoline engines but not the "ultimate solution" which as a society, we have no idea how to implement. The divisiveness of many political stands, including those on global climate change, where each side mis-represents the other in addition to its misguided rhetoric, is what is sad.

PL


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## Axel61 (Mar 10, 2011)

Ditto PL

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## wxmanCCM (Feb 17, 2010)

NOx emissions are regulated for two primary reasons - one is that NO2 (NOx is actually a "family" of oxides of nitrogen; NOx = NO + NO2 typically) has an ambient air quality standard (NAAQS); two is that it participates in the production of ground-level ozone (ozone is the primary constituent of "smog"). There are no areas in the U.S. that are in nonattainment with the NO2 NAAQS, and haven't been since 1998 (i.e., when Tier 1 was still in effect), so further NOx reductions are not indicated.

With respect to ozone production, NOx can either produce or destroy ozone, depending on the chemistry of the ambient air. Most urban areas in the U.S. (which are the areas which mostly are in nonattainment with the ozone NAAQS) have been shown to be "VOC limited" with respect to ozone production. In VOC-limited conditions, NOx actually destroys ozone, and reducing NOx can actually result in increasing levels of ground-level ozone. This is fundamental atmospheric chemistry, and has been documented for decades when ambient NOx levels are significantly reduced on weekends (mostly from a very large reduction in diesel truck traffic) in a phenomenon known as the "weekend ozone effect."

It would be much better to dramatically reduce NMOG/VOC emissions while S-L-O-W-L-Y reducing NOx emissions. EPA has acknowledged the disbenefit of reducing NOx in VOC-limited areas, but has apparently decided that it is more politically palatable to concentrate on NOx emissions from diesels rather than VOC emissions from gassers.


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## sirbikes (Aug 17, 2012)

Yes, this is how i can tell. It's not hard. I get the major regens. Smaller ones and any passive regens I miss.



mefferso said:


> Im sorta ocd about watching my instantaneous mpg dial and when drops about 10 mpg below normal for 10-15 miles is when its occurring.


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## sirbikes (Aug 17, 2012)

Just the DPF, or are you also removing the SCR cat and associated parts as well. Who is doing your coding out, or are you leaving the sensors in the new pipe?



Axel61 said:


> cant wait to remove the DPF my downpipe will be finished this weekend thanks to 2deerwhistlers, anyone want a downpipe contact him any X5d need to send him a DPF so he can make a prototype and make some for our x5d brothers


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## F32Fleet (Jul 14, 2010)

wxmanCCM said:


> NOx emissions are regulated for two primary reasons - one is that NO2 (NOx is actually a "family" of oxides of nitrogen; NOx = NO + NO2 typically) has an ambient air quality standard (NAAQS); two is that it participates in the production of ground-level ozone (ozone is the primary constituent of "smog"). There are no areas in the U.S. that are in nonattainment with the NO2 NAAQS, and haven't been since 1998 (i.e., when Tier 1 was still in effect), so further NOx reductions are not indicated.
> 
> With respect to ozone production, NOx can either produce or destroy ozone, depending on the chemistry of the ambient air. Most urban areas in the U.S. (which are the areas which mostly are in nonattainment with the ozone NAAQS) have been shown to be "VOC limited" with respect to ozone production. In VOC-limited conditions, NOx actually destroys ozone, and reducing NOx can actually result in increasing levels of ground-level ozone. This is fundamental atmospheric chemistry, and has been documented for decades when ambient NOx levels are significantly reduced on weekends (mostly from a very large reduction in diesel truck traffic) in a phenomenon known as the "weekend ozone effect."
> 
> It would be much better to dramatically reduce NMOG/VOC emissions while S-L-O-W-L-Y reducing NOx emissions. EPA has acknowledged the disbenefit of reducing NOx in VOC-limited areas, but has apparently decided that it is more politically palatable to concentrate on NOx emissions from diesels rather than VOC emissions from gassers.


Well with gassers you do have vapor recovery at the pumps and charcoal filtering at the fueler neck. Getting rid of carburetors helped as well. In any case you're right but of course with areas such a LA car traffic doesn't really drop on weekends. In areas where both car and truck traffic drop on weekends O3 would also drop.

On a side note thankfully ULSD has about wiped out SOx. Of course port cities continue to have a problem because marine diesels don't use ULSD.

Can't wait for the day when we have compliant cartridge UREA Systems with NO EGR. Amminex.com


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## wxmanCCM (Feb 17, 2010)

BMWTurboDzl said:


> Well with gassers you do have vapor recovery at the pumps and charcoal filtering at the fueler neck. Getting rid of carburetors helped as well....


That's true, but gas cars (and even gas-electric hybrids) still produce far more NMOG/VOC emissions per mile on average than diesels. Please see the full analysis I posted on TDIclub at http://forums.tdiclub.com/showthread.php?p=4444647#post4444647 if you are interested.



BMWTurboDzl said:


> ...In any case you're right but of course with areas such a LA car traffic doesn't really drop on weekends. In areas where both car and truck traffic drop on weekends O3 would also drop....


Actually, ambient O3 levels still don't drop even in cases where both gasoline and diesel traffic drops. The best example is a very recent study in Israel of the "National Day of Atonement"....

"...A dramatic decrease in primary pollutants emissions (83-98% in NO) causes an 8 ppbv increase in ozone at the urban core. Downwind (27 km), ozone decreases by only 5 ppbv. Nighttime O3 is shown to increase to 20 ppbv at the urban sites and 30 ppbv downwind...."

Source: Ilan Levy, "A national day with near zero emissions and its effect on primary and secondary pollutants." _Atmospheric Environment_, Volume 77, October 2013, Pages 202-212, http://www.sciencedirect.com/science/article/pii/S1352231013003488 (abstract)



BMWTurboDzl said:


> ...Can't wait for the day when we have compliant cartridge UREA Systems with NO EGR. Amminex.com


Sounds promising!


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## TDIwyse (Sep 17, 2010)

sirbikes said:


> I think I'm seeing a downward trend in my average miles between regens. I have 75K on my vehicle. What could this mean ... DPF effectiveness waning, overfuel condition leading to more soot (I have a remap), carbon buildup? How to know?


I love it when wxman posts, it's always good stuff.

sirbikes, if you have something like the Bavarian Technic tool you can see the pressure delta pre/post DPF.

http://www.bimmerfest.com/forums/showpost.php?p=6695813&postcount=25

You could track the pressure delta over time for full fueling tests and see how it's loading up... As it ages the backpressure should continue to increase until it starts causing issues.

The Bav Tech will also show you exactly what's going on with the post injection events to raise the EGT's.

http://www.bimmerfest.com/forums/showpost.php?p=6692185&postcount=21

Also, the Android Torque App will show you exactly when you're doing a regen as well. And it's simple, cheap and easy to utilize with a blue tooth OBD dongle. This is a screen shot of my "gauge cluster" and you can see the EGR is 0% and the EGT's increase to ~1150F during a regen.


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## Nadir Point (Dec 6, 2013)

I prefer facts over feelings. I get a real creepy feeling when greenies feel sorry I don't feel the way they do.


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## Jamolay (May 11, 2014)

Nadir Point said:


> I prefer facts over feelings. I get a real creepy feeling when greenies feel sorry I don't feel the way they do.


I get creeped out when you use a word like "greenies" as if giving a **** about the environment that we live in is a bad thing. I am sorry, but there is a lot of data that pollution is bad, and blithely ignoring it for our convenience and pleasure is at our own peril. If course I pollute too, and make choices, I just try to make the best ones I can in a situation. But the attitude that pollution is not a problem and can be ignored is dangerous as it is ignorant.

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## TDIwyse (Sep 17, 2010)

Jamolay said:


> I get creeped out when you use a word like "greenies" as if giving a **** about the environment that we live in is a bad thing. I am sorry, but there is a lot of data that pollution is bad, and blithely ignoring it for our convenience and pleasure is at our own peril. If course I pollute too, and make choices, I just try to make the best ones I can in a situation. But the attitude that pollution is not a problem and can be ignored is dangerous as it is ignorant.
> 
> Sent from BimmerApp mobile app


Just some things to consider regarding wether or not the DPF actually improves or hurts "pollution", and what should be more important, human health.

http://www.sciencedirect.com/science/article/pii/S0021850210000960

_*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/vehiclesandfuels/pdfs/deer_2009/session8/deer09_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, 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/trans/doc/2013/wp29grpe/GRPE-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/roadsafety_library/publications/particulates_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/content/early/2013/09/16/toxsci.kft162.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 ***8722;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.*_


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## Nadir Point (Dec 6, 2013)

Jamolay said:


> But the attitude that pollution is not a problem and can be ignored is dangerous as it is ignorant.


That's why I prefer facts over feelings. You probably ignore things like the fact that manufacturing and shipping hybrid car batteries from China uses more energy and creates far more pollution than they save in their automotive applications. The greenies must feel good about that, driving their Prius' with holier than thou noses in the air.

Feel that warm, fuzzy greenhouse gas effect? Feels good, don't it! :bustingup


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## floydarogers (Oct 11, 2010)

Jamolay said:


> I get creeped out when you use a word like "greenies" as if giving a **** about the environment that we live in is a bad thing. I am sorry, but there is a lot of data that pollution is bad, and blithely ignoring it for our convenience and pleasure is at our own peril. If course I pollute too, and make choices, I just try to make the best ones I can in a situation. But the attitude that pollution is not a problem and can be ignored is dangerous as it is ignorant.


Bravo.:thumbup: I've kept out of this particular thread, as it just re-hashes things discussed before - many in this forum but also with a slightly different case over on E90Post: http://www.e90post.com/forums/forumdisplay.php?f=377 Many of the posters know my "greenie" opinions, but I've let them know them, arguing further is not going to change many of theirs, and arguing further is pointless and I'm not into adding pointless stress to my life.



Nadir Point said:


> That's why I prefer facts over feelings. You probably ignore things like the fact that manufacturing and shipping hybrid car batteries from China uses more energy and creates far more pollution than they save in their automotive applications. The greenies must feel good about that, driving their Prius' with holier than thou noses in the air.


See, here's where you're wrong: all the "greenies" I know are into WTW economic analysis and totally agree that electric cars without getting rid of coal-fired plants is useless (except in places like the Pacific NW and even California where most of our power is hydro/renewable). That's why my wife and I drive diesels, because they're better than hybrid or electrics in all but a few limited cases. Grow up and read some actual Green literature and commentary rather than repeating the pablum from Fox.


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## Nadir Point (Dec 6, 2013)

floydarogers said:


> See, here's where you're wrong: all the "greenies" I know are into WTW economic analysis and totally agree that electric cars without getting rid of coal-fired plants is useless (except in places like the Pacific NW and even California where most of our power is hydro/renewable).


Apparently you don't know Jamolay. :dunno:

So I'm wrong, but you agree with me. That's good to know, I suppose.


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## Pierre Louis (Oct 23, 2011)

The media circus has many biased and bad players, the least of which is Fox since it occupies the only right of center news reporting and garners much higher viewer ratings than the others. All media are biased, and people tend to like watching that which is agreeable and familiar. Facts seem not be too important for most media types including Fox. Witness 60 Minutes' crucifixion of Audi with the 5000 model unintended acceleration case. Every single final report concluded driver error but 60 Minutes unrepentantly re-aired their story blaming Audi long after these studies were published and didn't flinch from their bias. I almost prefer listening to the opposition, because the facts come out one way or another by being skeptical.

Thus we as information consumers should have the same skepticism when looking at environmental issues. Listener beware!

PL


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## FredoinSF (Nov 29, 2009)

Agree that many of the responses are reruns of prior discussions. Interesting stuff, but I feel we've gone off topic and I'm not seeing an answer to the question in the original post. Maybe it's buried in one of the responses and if it is I apologize. I was interested in reading feedback from anyone who may have experienced this, particularly on the X5 since most CBU reports seem to come from E90 owners. 


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## F32Fleet (Jul 14, 2010)

wxmanCCM said:


> That's true, but gas cars (and even gas-electric hybrids) still produce far more NMOG/VOC emissions per mile on average than diesels. Please see the full analysis I posted on TDIclub at http://forums.tdiclub.com/showthread.php?p=4444647#post4444647 if you are interested.
> 
> Actually, ambient O3 levels still don't drop even in cases where both gasoline and diesel traffic drops. The best example is a very recent study in Israel of the "National Day of Atonement"....
> 
> ...


Is that drop by 5 considered relevant ? Of course these are short term effects. If the long term meant an overall reduction in O3 then that paints a different picture. I don't know how you would be able to figure that out.


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## wxmanCCM (Feb 17, 2010)

BMWTurboDzl said:


> Is that drop by 5 considered relevant ? Of course these are short term effects. If the long term meant an overall reduction in O3 then that paints a different picture. I don't know how you would be able to figure that out.


This is just the latest in a series of studies on this issue.

There have been at least 13 peer-reviewed studies (10 of which were independent) published in respected scientific journals in the past decade or so focusing on the "weekend ozone effect." All of these studies concluded that the increases in ozone levels on weekends were the results of larger reductions in NOx (oxides of nitrogen) emissions (mostly from a very large decrease in diesel truck traffic) than other ozone "precursors" (e.g., volatile organic compounds (VOC), carbon monoxide). EPA refers to this phenomenon as the "NOx reduction disbenefit."

One of those more recent studies (Blanchard, Tanenbaum, Lawson; "Differences between Weekday and Weekend Air Pollutant Levels in Atlanta; Baltimore; Chicago; Dallas-Fort Worth; Denver; Houston; New York; Phoenix; Washington, DC; and Surrounding Areas." _Journal of the Air & Waste Management Association_, Volume 58, December 2008, Pages 1598-1615) concludes that all of these large urban areas in the U.S. are "VOC-limited" with respect to ozone formation, and thus potentially may see increases in ambient ozone levels as a result of several EPA regulations which mandate large reductions in NOx emissions from on-road and off-road diesel engines. Note that Atlanta is classified as VOC-limited in spite of large biogenic VOC sources in the southeast.

Even EPA expected increases in ambient ozone levels in urban areas based on "Regulatory Impact Analysis" documents (RIA) of its regulations of NOx emissions reductions from diesel engines. For example, EPA specifically acknowledges that "&#8230;It should be noted, however, that the potential exists for a few localized areas to actually experience slight increases in ozone concentrations as a result of NOx emission reductions...." (EPA Final Regulatory Impact Analysis: Control of Emissions of Air Pollution from Highway Heavy-Duty Engines, http://www.epa.gov/otaq/regs/hd-hwy/1997frm/hwy-ria.pdf , page 119). In another RIA, EPA actually projected that one county (Bronx County in New York) which was not in violation of the ozone NAAQS at the time of the RIA, would violate the standard by 2020 as a result of its regulation (EPA Final Regulatory Impact Analysis: Control of Emissions from Nonroad Diesel Engines, page 2-114, available at http://www.noticeandcomment.com/-fi...nes-epa420-r-04-007-dcn-se03157-fn-43776.aspx). It also acknowledged in that RIA that its air quality modeling predicted NOx reduction disbenefits generally in the areas identified by some studies as "VOC-limited" (e.g., Los Angeles) (page 2-223). On page 2-36 of another RIA (EPA Regulatory Impact Analysis: Control of Emissions of Air Pollution from Locomotive Engines and Marine Compression Ignition Engines Less than 30 Liters Per Cylinder), EPA states that its modeling indicated that 5 counties would experience increases in ambient ozone levels as a result of that specific rule, and that one county (Orange County, California) would experience a 5.5 ppb increase in ozone levels because of the NOx reduction disbenefit in those areas.

It should be pointed out that EPA specifically states that VOC reductions in "NOx-limited" areas have virtually no effect, i.e., there's no "VOC reduction disbenefit" in rural areas (normally expected to be "NOx-limited"). Thus there doesn't appear to be any valid scientific reason for EPA to focus on NOx emission reductions while doing little to further reduce VOC emissions, and its recent emission reduction strategies and priorities are perplexing, if not misguided.

I would like to state unequivocally that I am not opposed to reductions in emissions in general. However, EPA should take a more cautious approach in formulating its regulations, especially taking the latest scientific information into account, not just indiscriminately mandating emission reductions. The regulations have also had economic impacts in that diesel engines have become significantly more expensive and less fuel efficient, and have the effect of discouraging some auto manufacturers of introducing fuel-efficient diesel engines in their cars.


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## TDIwyse (Sep 17, 2010)

FredoinSF said:


> Agree that many of the responses are reruns of prior discussions. Interesting stuff, but I feel we've gone off topic and I'm not seeing an answer to the question in the original post. Maybe it's buried in one of the responses and if it is I apologize. I was interested in reading feedback from anyone who may have experienced this, particularly on the X5 since most CBU reports seem to come from E90 owners.
> 
> Sent from BimmerApp mobile app


I think my post #27 would give testable and quantifiable evidence that would answer his question...


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## FredoinSF (Nov 29, 2009)

TDIwyse said:


> I think my post #27 would give testable and quantifiable evidence that would answer his question...


Thanks. I missed it among the other responses. Again, great info here and it is humbling to see the level of knowledge to be gained.
The tools in post 27 would provide data about the regen and that would be something of interest to me because I have not been able to detect a regen taking place while driving. 
That being said, any thoughts about more frequent regen being an indicator of increasing CBU? Or would those more frequent regens be more of an indicator that the particulate filter is becoming less effective and is getting close to failing? How can a responsible owner translate it in terms of actionable steps he/she can take to perform preventive maintenance or know that it is an indicator for impending failure of a given part? 
I'm a simple guy looking for simple answers. Clearly my knowledge and understanding in this field needs improvement.

Sent from BimmerApp mobile app


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## F32Fleet (Jul 14, 2010)

wxmanCCM said:


> This is just the latest in a series of studies on this issue.
> 
> There have been at least 13 peer-reviewed studies (10 of which were independent) published in respected scientific journals in the past decade or so focusing on the "weekend ozone effect." All of these studies concluded that the increases in ozone levels on weekends were the results of larger reductions in NOx (oxides of nitrogen) emissions (mostly from a very large decrease in diesel truck traffic) than other ozone "precursors" (e.g., volatile organic compounds (VOC), carbon monoxide). EPA refers to this phenomenon as the "NOx reduction disbenefit."
> 
> ...


Got it. Years ago our EPD made the statement that Atlanta would have a hard time meeting AQ goals because of the naturally high levels of VOC.

So basically the point is being made that NOX reduction in urban areas is actually making, temporarily at least (couple of days), ozone levels increase slightly whereas in more rural areas it will slightly.

I wonder if the EPA is taking a big picture approach. Looking for net reductions as a whole over most of the time?

From what I'm reading there really is no reason for EGR unless HC increase with out it. I've seen conflicting studies on PM with and without EGR.

Imagine what AQ would be like if cars levitated and ran on hydrogen!!


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## wxmanCCM (Feb 17, 2010)

BMWTurboDzl said:


> ...I wonder if the EPA is taking a big picture approach. Looking for net reductions as a whole over most of the time?...


In the RIAs I referenced previously, that was EPA's justification for the mandated reductions in NOx from diesel engines; that most locations would see a net reduction in ambient O3 levels, even if a few small areas (mostly urban cores) see increases in O3 levels.

However, I don't see why this doesn't violate the "Environmental Justice" Executive Order that was originally signed by President Clinton in 1994 (IIRC) in spirit, if not letter. If I understand that EO correctly, regulations promulgated by federal agencies are not supposed to degrade environmental conditions for a few, especially in urban cores where more disadvantaged live, even if environmental conditions are improved for the vast majority. EPA seems to admit to violating that edict.


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## sirbikes (Aug 17, 2012)

This is awesome, thanks!



TDIwyse said:


> I love it when wxman posts, it's always good stuff.
> 
> sirbikes, if you have something like the Bavarian Technic tool you can see the pressure delta pre/post DPF.
> 
> ...


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## F32Fleet (Jul 14, 2010)

wxmanCCM said:


> In the RIAs I referenced previously, that was EPA's justification for the mandated reductions in NOx from diesel engines; that most locations would see a net reduction in ambient O3 levels, even if a few small areas (mostly urban cores) see increases in O3 levels.
> 
> However, I don't see why this doesn't violate the "Environmental Justice" Executive Order that was originally signed by President Clinton in 1994 (IIRC) in spirit, if not letter. If I understand that EO correctly, regulations promulgated by federal agencies are not supposed to degrade environmental conditions for a few, especially in urban cores where more disadvantaged live, even if environmental conditions are improved for the vast majority. EPA seems to admit to violating that edict.


Well executive orders can be overturned by the next Administration. I almost forgot that NOX isn't only about ozone but acid rain. (ex. Mt. Mitchell)


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## wxmanCCM (Feb 17, 2010)

BMWTurboDzl said:


> Well executive orders can be overturned by the next Administration. I almost forgot that NOX isn't only about ozone but acid rain. (ex. Mt. Mitchell)


True, but every admin since the Clinton admin has adopted this EO, including the current one - http://epa.gov/environmentaljustice/resources/publications/interagency/ej-mou-2011-08.pdf.

Acid rain was the topic of my research for my Masters thesis back in the mid-1980s when acid rain was still a big environmental issue. Based on my thesis research, NOx (actually NO3) is not very strongly correlated with rain water pH (r2 = 0.407). Sulfate (SO4) had the best correlation (r2 = 0.777).


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## mattebury (Feb 2, 2014)

wxmanCCM said:


> Based on my thesis research, NOx (actually NO3) is not very strongly correlated with rain water pH (r2 = 0.407). Sulfate (SO4) had the best correlation (r2 = 0.777).


How many people are gonna know what r2 is? And 0.777 is not all that great a correlation, I like to see something in the 90's, (0.9xxx that is  )


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## TDIwyse (Sep 17, 2010)

mattebury said:


> How many people are gonna know what r2 is? And 0.777 is not all that great a correlation, I like to see something in the 90's, (0.9xxx that is  )


Those of us who are technically inclined and involved in engineering/science will  We're also likely the only ones who are really, really enjoying the gritty details being discussed.

http://en.wikipedia.org/wiki/Coefficient_of_determination


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## sirbikes (Aug 17, 2012)

This sucker's going fast. DPF regens are dropping below 200 miles per. MPG seems to be suffering as well. I might need to get that tool to see what's going on but it's expensive and I don't even have a pc laptop. Anything else I could do? Take it to my shop and have them look at it?


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## F32Fleet (Jul 14, 2010)

sirbikes said:


> This sucker's going fast. DPF regens are dropping below 200 miles per. MPG seems to be suffering as well. I might need to get that tool to see what's going on but it's expensive and I don't even have a pc laptop. Anything else I could do? Take it to my shop and have them look at it?


If you do take it in be prepared to just have it cleaned. Just make sure you're comparing year over year and trying to account for any long /short trips as well as temps during these times.

FWIW it has been hotter on my neck of the woods when compared to last year but most importantly traffic has been worse and I didn't road trip last month.


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