# 2011 335d : 69k and CBU



## Pierre Louis (Oct 23, 2011)

If decreased fuel economy is a function of CBU, then all of my diesels with EGR haven't had it - yet. 

2002 TDI: 156,000 miles: no decrease, no CBU "problem"
2004 TDI: 110,000 miles: no decrease, no CBU "problem"
2005 CDI: 240,000 miles: no decrease, no CBU "problem" EGR replaced w/newer version due to defective original at about 60k
2011 335d: 57,000 miles: fuel economy seems better, no CBU "problem" - yet

Only "top tier brand" fuel, no aftermarket additive, regular maintenance, no mods, regular occasional WOT causing nice black plume of smoke (except of course the 335d has the DPF).

PL


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## bballfreak (Jul 27, 2010)

Good to know, Pierre that you have no problems with 335d and other diesels.
Shop foreman suggested BG fuel diesel additive, and BG makes good products.
BMW dealer carries BG44 for regular gasoline cars and not diesel.
Not advocating to use BG244 as it is not cheap, am just scared about this
CBU.
I know by mistake only once I used Valero diesel very initially when the car was
new and my mpg dropped from 36 to 27. Since, then I use only Chevron diesel which supposedly 
has the highest cetane for diesel in Texas. BP is supposedly the highest cetane in US but no BP where
I live.


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## KeithS (Dec 30, 2001)

You need to realize there are limited sources of fuel for any given area. That in most cases all the brands in an area can actually come from the same 1-2 sources. In the case of gasoline the big difference is the additive package. The brand specific additives are added at the fuel depot as they are loading the tanker truck to bring to the station (it's well mixed by the time they get there). Just as there is no such thing as midgrade at the fuel depot, they just mix premium and regular into the tanker truck. Many stations no longer have midgrade tanks (sometimes repurposing for diesel) as this mixing is now done in the pump.

In the case of diesel, I do not believe there is such a thing as a brand specific additive package. 
Unless there is a sticker on the pump indicating higher cetane (which they can be held to), I would not put much into anything verbally said about higher cetane. I believe what is more important for diesel is that it's fresh and to get it from a station with high volume/turnover. In this manner you also get a better seasonally adjusted blend (don't they add a little kerosene in colder weather?).


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## Pierre Louis (Oct 23, 2011)

bballfreak said:


> Good to know, Pierre that you have no problems with 335d and other diesels.
> Shop foreman suggested BG fuel diesel additive, and BG makes good products.
> BMW dealer carries BG44 for regular gasoline cars and not diesel.
> Not advocating to use BG244 as it is not cheap, am just scared about this
> ...


Yeah, I seem to trust BG but don't really know what to do, unless of course I get a CEL w/possible CBU as a cause. I am having an active conversation with my private mechanic on this and other issues. Car runs fine since new NOx sensors, new catalytic converters put in around 25,000 miles (I theorize its when I used a "fuel stabilizer" additive and started doing WOT which may have fried the catalytic converters, dunno).

My car may have the latest DDE and programming as it is a late build 2011. DPF regen frequency seems to have decreased over the last 20k miles also.

PL


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## Pierre Louis (Oct 23, 2011)

KeithS said:


> You need to realize there are limited sources of fuel for any given area. That in most cases all the brands in an area can actually come from the same 1-2 sources. In the case of gasoline the big difference is the additive package. The brand specific additives are added at the fuel depot as they are loading the tanker truck to bring to the station (it's well mixed by the time they get there). Just as there is no such thing as midgrade at the fuel depot, they just mix premium and regular into the tanker truck. Many stations no longer have midgrade tanks (sometimes repurposing for diesel) as this mixing is now done in the pump.
> 
> In the case of diesel, I do not believe there is such a thing as a brand specific additive package.
> Unless there is a sticker on the pump indicating higher cetane (which they can be held to), I would not put much into anything verbally said about higher cetane. I believe what is more important for diesel is that it's fresh and to get it from a station with high volume/turnover. In this manner you also get a better seasonally adjusted blend (don't they add a little kerosene in colder weather?).


It seems obvious to me that branded fuel has its own specific additive package - how specific I don't know. There are diesel pumps at branded stations that specify that the diesel is not branded. Fuel suppliers like Murphy's have been caught bragging that the difference in price is due to cheaper additive. I would imagine the additive package is even more important in diesel than in gasoline.

Sure, the base stock may be from the same refinery, but the additives are different. Having "some guy on the Internet" tell me it isn't, as you may have read also, doesn't convince me.

PL


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## KeithS (Dec 30, 2001)

Pierre Louis said:


> Sure, the base stock may be from the same refinery, but the additives are different. Having "some guy on the Internet" tell me it isn't, as you may have read also, doesn't convince me.PL


I'm not 100% positive on diesel, but I cannot find anything relating to additives, other than the aftermarket ones you can put in your tank yourself. I always was under the belief the diesel that ended up in your tank is pretty much what came out of the originating refinery (which is what we want, no water, rust, contaminates, algae, etc). But for gasoline I am sure. I use to manage an IT group that supported 40 fuel terminals in the NorthEast (Maine to VA) for a very major oil company. But true, I am just some guy on the internet.

But in the case of BBallFreak, if you are in the area of "refinery alley", Texas or Louisiana, there is much more diversity to fuel supply than most other locations in the country.


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## Nadir Point (Dec 6, 2013)

CBU and fuel quality are unrelated issues, unless you are talking about fuel contamination to the point where it is causing incomplete combustion and other fuel system problems related to fuel contamination. That being the case, CBU is not your biggest worry.


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## Pierre Louis (Oct 23, 2011)

Nadir Point said:


> CBU and fuel quality are unrelated issues, unless you are talking about fuel contamination to the point where it is causing incomplete combustion and other fuel system problems related to that. That being the case, CBU is not your biggest worry.


Perhaps, but there are reports among dealer service departments that CBU can be a regional problem. Unless we know specifically what factors are involved causing CBU in one engine and not so much another, any conclusions on fuel quality should be very suspect.

PL


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## Pierre Louis (Oct 23, 2011)

KeithS said:


> I'm not 100% positive on diesel, but I cannot find anything relating to additives, other than the aftermarket ones you can put in your tank yourself. I always was under the belief the diesel that ended up in your tank is pretty much what came out of the originating refinery (which is what we want, no water, rust, contaminates, algae, etc). But for gasoline I am sure. I use to manage an IT group that supported 40 fuel terminals in the NorthEast (Maine to VA) for a very major oil company. But true, I am just some guy on the internet.
> 
> But in the case of BBallFreak, if you are in the area of "refinery alley", Texas or Louisiana, there is much more diversity to fuel supply than most other locations in the country.


Its hard to find, I agree. Here are two references and a journalist's opinion FYI:

http://www.chevron.com/documents/pdf/DieselFuelTechReview.pdf



> Fuel marketers have a legal requirement to provide a product that meets all applicable specifications. Beyond that, reputable fuel suppliers ensure that the non-specification prop- erties, such as stability and low-temperature operability, are suitable for the intended use.
> The marketer has several options on how to achieve the desired properties: choice of crude oil, refinery processing, refinery blending, or the use of additives. The balance between refining actions and additive use is driven by economics. Because there are no legal require- ments that diesel fuel contain additives, except red dye in high-sulfur and tax-exempt fuel, some refiners may use no additives at all and still provide a high-quality fuel.
> There is no published information on the extent to which diesel additives are used in the marketplace. The following comments represent the authors' impression of common industry practice in the U.S.:
> • Currently, because of the recent adoption of a lubricity specification, lubricity additive is the most widely used diesel additive nationwide all year round. Because of pipeline regulations in the U.S., lubricity additives are added at the terminals.


http://www.akenergyauthority.org/PDF files/Diesel Fuel Additives.pdf



> Pour point, lubricity, and conductivity additives are mixed at various stages in the supply chain. Some pour point additives, for instance, need to be blended with the fuel at high temperatures, and are added to the fuel at refineries as a result, while other pour point depressants can be added at lower temperatures [51]. This requirement seems to reflect the general wisdom of vendors and users of additives - good physical mixing of the additives into the fuel is imperative, and can depend upon the chemistry of the additive and the fuel stock as well as the temperature during the mixing process.
> 33
> Percentage of Utilities in Bin
> Lubricity additives are necessary in most ULSD fuels, but there are strict limitations on the maximum concentration of lubricity additives in jet fuel, because it can decrease the efficacy of fuel filters and water separators [106] due to the hydroscopic properties of the additive. The responsibility of meeting the ASTM lubricity standard often falls to distributors, who blend an additive with the fuel after it has been transported but before selling it to the consumer [15]. This is consistent with reports from Egegik that Crowley blends a lubricity additive with their fuel at the fuel dock. Without the lubricity additive, ULSD fuels most likely will not meet lubricity requirements-"If the lubricity additive is offered-take it" [51].


http://www.simplemotoring.co.uk/supermarket-vs-branded-fuels/



> The base fuel is the same for all companies - in fact, it usually comes from the same tanks at the local fuel refinery/distribution centre. What varies is the additives package that goes into the fuel. These additives packages are secret recipes of extra ingredients that help keep the engine clean and improve lubrication inside the engine cylinders.
> Each fuel company has its own additives packages and these are different. So it is possible (but not common) for some drivers to feel that their car responds better to the additives used by one fuel manufacturer over those of another.


I've read differing opinions and various accounts of how additives are added before the fuel ends up in your tank at the station.

PL


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## Hoooper (Jun 17, 2013)

I would imagine whether fuel quality played a part or not CBU would still be regional. In regions where people spend a lot of time making short trips and being stopped, CBU should be more prevalent. In places where people are driving 10+ miles every time they get in the car and frequently going 30+, CBU should be less prevalent. There are also likely some regions where diesels would not have sold as well and as such obviously there would be fewer CBU results.


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## Pierre Louis (Oct 23, 2011)

Hoooper said:


> I would imagine whether fuel quality played a part or not CBU would still be regional. In regions where people spend a lot of time making short trips and being stopped, CBU should be more prevalent. In places where people are driving 10+ miles every time they get in the car and frequently going 30+, CBU should be less prevalent. There are also likely some regions where diesels would not have sold as well and as such obviously there would be fewer CBU results.


Yes, my technically astute nephew in France says Peugeot diesels used around town are more prone to CBU. He does his own engine work and was captain of a huge merchant ship before he retired.

PL


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## Rob Sheriff (Dec 4, 2014)

I have a 2011 335d (48K miles) that just spent the month of December at the dealer having the CBU issue taken care of. Not 5 days after I picked it up, the SES light came on. It's been off and on 10x the month of January. The fault code says P244a - Diesel Particulate Filter Differential Pressure Too Low. Any ideas? I don't really want to take it back to the dealer. I'm hoping it is something simple, but I am learning a lot from these forums that it probably won't be . . .


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## ingenieur (Dec 26, 2006)

There are 2 lines going to the DPF pressure sensor - perhaps take a look that they are installed fully and correctly.


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## bballfreak (Jul 27, 2010)

Have a 2009 335d with 51K miles and have been lucky, so far. Based on the recommendation of the shop foreman, I drive it hard once a month and then I add BG244- diesel additive 
and hope that helps the CBU and also use name brand diesel fuel like Chevron. But this is scary, love this car, and cannot understand why BMW does not address this problem. There should be a class action lawsuit.


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