[Hoooper]

Originally Posted by floydarogers

What evidence could possibly be provided to show that there is no evidence? I have to assume you arent serious because I just cant imagine someone asking for evidence of no evidence.

[Pierre Louis]

There are many beliefs and statements typed into message boards that have no basis in data or fact. Opinions are, uh, free of accountability it seems and data is scarce.

I've read entire threads that had evidence that was obvious to the contrary (on other boards) in the thread itself yet the common beliefs were unchanged.

Its human to have such bias, and I can see it pretty often. This reminds me of political discussions, obviously more severe than on a message board of car enthusiasts, that illuminate the concepts of "brute opportunism" http://ideamaidan.com/FoulFair.html,

"Not only in regards to the 'fellow travelers' themselves, but also for a certain segment of the broader public who tend to be receptive to this spirit of 'brute oppositionism', the self-righteous rejection of such things as logical consistency or ethical integrity, along with the whole 'anti-intellectual' character underlying this spirit, may very well signify a state of affairs that will prove entirely impervious to any efforts involving an 'educative' approach. Depressing as it might be to concede, it is possible that such people cannot be brought to see the error of their ways by any means, simply in that they have purposely chosen error."

...and the psychology of belief: http://newsoffice.mit.edu/2015/corre...al-rumors-0505 which contains excerpts from the paper containing such results, “Rumors, Truths, and Reality: A Study of Political Misinformation,” to be published in the British Journal of Political Science.

Just interesting as examples of the importance of at least real data, but how even science doesn't seem to affect many believers. Not a surprise, eh?

At any rate, I hope someone with more time and patience than me tries to collect all posters on both boards with CBU to estimate, theoretically, the percentage of 335d's and X35d's that have it, of the 10,000 sold.

Cheers,

PL

[melonbread]

Originally Posted by Thisonegoestoeleven

FWIW I did my cleaning at 100k or so as preventative, but they said it was "pretty bad". The car did almost exclusively highway. First 60k were in Louisiana, the next 35k were in Colorado and Wyoming. Lots of cross country road trips interspersed. 34mpg average with a mix of fairly spirited driving and highway loafing at 2k rpm in 6th. I had a slight mpg dip(32 mpg) when I got into the high 90k's, so I figured it was time to get a clean slate.

Where did you get your cbu cleaned and how much did it take? Im averaging 32 mpg mostly on highway going 75-85mph. My car has 46k and my factory warranty is about to expire. Debating to purchase extended warranty or go get a cbu clean out of pocket cost.

Dealer wont honor cbu unless ses light comes on with proper code...

[floydarogers]

Originally Posted by Yozh

May I ask if you had a chance to physically inspect your intake for CBU evidence. I, personally can not say whether my car has or does not have CBU. I have never looked.

No, I have to admit I haven't looked - meant to have my indy try to borescope it last month when it was in, but slipped my mind to ask them. I can tell you that mileage and performance (perceived - I haven't run down to Pacific Raceways to run a 1/4 mile) have not slipped. I've not gotten a single code/sel related to anything but the stupid SCR/DEF system since I got an adaptation fault a couple months into my ownership either. My indy hasn't got the special wand, as they haven't had any cases. Haven't asked at BMW Bellevue because, well, I haven't been except for SCR issues, and that was almost 2 years ago in the 70K-80K timeframe.

[Pierre Louis]

Inductive reasoning that there are cars that don't have CBU related problems at all, even after 156,000 to 240,000 miles (my old Mercedes E320 CDI - which did have a redesigned EGR put in, BTW) should stop people from believing that all cars will (eventually) get it, and that one needs to take the head off to find out.... I don't believe there are many that do the boroscope for no reason either.

Engineering is truly the art of compromise - you can design a fuel pump, for example, that will go for a million miles, but it will be more expensive than the rest of the car, for example.

We all know that BMW probably compromised too much in the case of CBU, and that it is unacceptable to even have the small percentage that report it online to have it.

PL

[Thisonegoestoeleven]

Originally Posted by melonbread

Where did you get your cbu cleaned and how much did it take? Im averaging 32 mpg mostly on highway going 75-85mph. My car has 46k and my factory warranty is about to expire. Debating to purchase extended warranty or go get a cbu clean out of pocket cost.

Dealer wont honor cbu unless ses light comes on with proper code...

I had the cleaning performed by an Indy shop in Los Angeles for 2k.

[NC335d]

Originally Posted by melonbread

Where did you get your cbu cleaned and how much did it take? Im averaging 32 mpg mostly on highway going 75-85mph. My car has 46k and my factory warranty is about to expire. Debating to purchase extended warranty or go get a cbu clean out of pocket cost.

Dealer wont honor cbu unless ses light comes on with proper code...

I just got my CBU cleaning done at 43k as a preventative measure, since I saw many people were experiencing issues right after the factory warranty ran out. I bought the car last June 2011 CPO with 21k on it, but got bitten by the mod bug early on. Commuted 120 miles to work roundtrip 80% highway (70-85mph.) and averaged around 34.5 mpg (hand calculated) with the RennTech tune. When the indy shop pulled the intake off there was quite a lot of build up. I figured I would have issues w/ CBU eventually and BMW/dealership issues with the car being modded, so I decided to do the alphabet delete at the same time. I plan on getting the cleaning done again at around the 90k mark to be on the safe side as I intend to keep the car for a while.

[NC335d]

Originally Posted by Thisonegoestoeleven

I had the cleaning performed by an Indy shop in Los Angeles for 2k.

$2k seems a little bit too high. Did they replace all the seals as well? I ordered all the seals etc. for approx. $200 from ECS. I think $1,500 is about right if they inc. the seals. The problem is, not many indys will touch the diesels due to their unfamiliarity with them and the special wands required. I guess beggars can't be choosers though. Leith BMW in Raleigh, NC quoted me $3,200 which included injector recalibration.

[Thisonegoestoeleven]

Originally Posted by NC335d

$2k seems a little bit too high. Did they replace all the seals as well? I ordered all the seals etc. for approx. $200 from ECS. I think $1,500 is about right if they inc. the seals. The problem is, not many indys will touch the diesels due to their unfamiliarity with them and the special wands required. I guess beggars can't be choosers though. Leith BMW in Raleigh, NC quoted me $3,200 which included injector recalibration.

Seals were replaced. I've heard of the 1500 price point, but I was in the area and didn't feel like waiting around. Sometimes I have patience to deliberate for the best deal possible. Sometimes I compromise for convenience. I basically made the decision to do it and that was the preferred option of the shops in the area capable. Even so, spread out over 100k miles, it's not too much of an issue, if budgeted for ahead of time. Now if it was occurring more frequently, then it might be more of an issue.

[MinPA]

I'm considering a 335d once VW takes back my TDI. It will either be replaced with a 335d or an E90 335i. The performance and fuel economy/range of the 335d is very alluring. I love the low-end, effortless pull of a diesel motor for daily driving!

When the EGR is removed and a tune is applied, have people found these cars to be otherwise reliable? I understand eliminating all carbon build up isn't realistic, but I'm ok with doing the service only once or twice over the expected 150k mile life of the car. Thanks

[Hoooper]

Originally Posted by MinPA

I'm considering a 335d once VW takes back my TDI. It will either be replaced with a 335d or an E90 335i. The performance and fuel economy/range of the 335d is very alluring. I love the low-end, effortless pull of a diesel motor for daily driving!

When the EGR is removed and a tune is applied, have people found these cars to be otherwise reliable? I understand eliminating all carbon build up isn't realistic, but I'm ok with doing the service only once or twice over the expected 150k mile life of the car. Thanks

I'm nearing 150k on mine without a carbon cleaning, about 90k of that is with egr blocked. I'd say if you block the egr and clean any build up it already has you should easily be able to get 150k with 1 or 0 cleanings.

[dmanb2b]

Originally Posted by MinPA

I'm considering a 335d once VW takes back my TDI. It will either be replaced with a 335d or an E90 335i. The performance and fuel economy/range of the 335d is very alluring. I love the low-end, effortless pull of a diesel motor for daily driving!

When the EGR is removed and a tune is applied, have people found these cars to be otherwise reliable? I understand eliminating all carbon build up isn't realistic, but I'm ok with doing the service only once or twice over the expected 150k mile life of the car. Thanks

My 335D is in the garage and VW is parked in back yard :>). Welcome

[DWR]

Originally Posted by Hoooper

I'm nearing 150k on mine without a carbon cleaning, about 90k of that is with egr blocked. I'd say if you block the egr and clean any build up it already has you should easily be able to get 150k with 1 or 0 cleanings.

Yeah, it is hard to imagine how you can get CBU without the source of carbon.

[Hoooper]

Originally Posted by DWR

Yeah, it is hard to imagine how you can get CBU without the source of carbon.

Just typical gasser style CBU, carbon buildup on the valves presumably from crankcase vent oil mist.

[QUIKDZL]

I'm one of the fortunate ones--115k miles with no CBU issues. I think I know why now. 14k miles ago I installed an oil catch can and water/meth injection to prevent the inevitable. After 14k miles, however, the can had only caught about half an ounce of oil. It seems that my engine produces very little blow-by.

I was seeing a few throttle sticking codes prior to this, but now the engine has consumed about six gallons of water/meth. The throttle codes disappeared after about a gallon of w/m consumption. I don't think I'll ever have CBU problems.

[lnxguy]

Originally Posted by QUIKDZL

I'm one of the fortunate ones--115k miles with no CBU issues. I think I know why now. 14k miles ago I installed an oil catch can and water/meth injection to prevent the inevitable. After 14k miles, however, the can had only caught about half an ounce of oil. It seems that my engine produces very little blow-by.

I was seeing a few throttle sticking codes prior to this, but now the engine has consumed about six gallons of water/meth. The throttle codes disappeared after about a gallon of w/m consumption. I don't think I'll ever have CBU problems.

Have you actually pulled the intake and done a visual?

[Tomnavigator]

All,
Thanks for your comments. I started this thread hoping to generate a good discussion on carbon buildup. I would like to add information and present another view on a few of the comments I saw on this thread.

1) I live four miles from the Citgo oil refinery near Lake Charles, LA. There is a bulk fuel terminal that loads gasoline and diesel into 18 wheelers. The loading terminal loads Mobil/Exxon trucks, Valaero trucks, Chevron trucks, Texaco trucks, etc. Everyone gets the same fuel. The only difference is the additive. There are at least six tanks labeled Exxon/Mobil additive, Texaco additive, Chevron additive, etc. Every trucks get the same fuel and a certain amount of the appropriate additive. All the oil companies work together this way around the country. All gas stations near a Chevron terminal gets Chevron gasoline. Only the additives change. Think about it. It makes sense for the companies to work together this way so they all don't have to have terminals in every geographic location. The fuel is the same no matter which station you get it at. Only the detergent additive is different.
2) I think most people buy diesels in an effort to save in transportation costs. I drive 140 miles (round trip) to work each day. I bought a diesel to reduce my costs. The only low cost (practical) ways to prevent CBU is to install a catch can and/or eliminate the EGR. I don't want to bypass my pollution prevention devices. However, I would prefer that my car runs. So far I have not blocked my EGR because this will effect the NOx and therefore the SCR system that injects the urea mixture. I am waivering on blocking the EGR because I don't see any cost effective alternative.
3) I still wait for someone to learn to code out the EGR and charge a reasonable fee for this service. I don't want a performance tune that creates new problems. I don't want to spend thousands of dollars to have a dependable car. Any modification I make must be cost effective and increase reliability.

[Tomnavigator]

All,
Thanks for your comments. I started this thread hoping to generate a good discussion on carbon buildup. I would like to information and another view on a few of the comments I saw on this thread.

1) I live four miles from the Citgo oil refinery near Lake Charles, LA. There is a bulk fuel terminal that loads gasoline and diesel into 18 wheelers. The loading terminal loads Mobil/Exxon trucks, Valaero trucks, Chevron trucks, Texaco trucks, etc. Everyone gets the same fuel. The only difference is the additive. There are at least six tanks labeled Exxon/Mobil additive, Texaco additive, Chevron additive, etc. Every trucks get the same fuel and a certain amount of the appropriate additive. All the oil companies work together this way around the country. All gas stations near a Chevron terminal gets Chevron gasoline. Only the additives change. Think about it. It makes sense for the companies to work together this way so they all don't have to have terminals in every geographic location. The fuel is the same no matter which station you get it at. Only the detergent additive is different.
2) I think most people buy diesels in an effort to save in transportation costs. I drive 140 miles (round trip) to work each day. I bought a diesel to reduce my costs. The only low cost (practical) ways to prevent CBU is to install a catch can and/or eliminate the EGR. I don't want to bypass my pollution prevention devices. However, I would prefer that my car runs. So far I have not blocked my EGR because this will effect the NOx and therefore the SCR system that injects the urea mixture. I am waivering on blocking the EGR because I don't see any cost effective alternative.
3) I still wait for someone to learn to code out the EGR and charge a reasonable fee for this service. I don't want a performance tune that creates new problems. I don't want to spend thousands of dollars to have a dependable car. Any modification I make must be cost effective and increase reliability.

[RollingCoal]

Originally Posted by Tomnavigator

All,
Thanks for your comments. I started this thread hoping to generate a good discussion on carbon buildup. I would like to add information and present another view on a few of the comments I saw on this thread.

1) I live four miles from the Citgo oil refinery near Lake Charles, LA. There is a bulk fuel terminal that loads gasoline and diesel into 18 wheelers. The loading terminal loads Mobil/Exxon trucks, Valaero trucks, Chevron trucks, Texaco trucks, etc. Everyone gets the same fuel. The only difference is the additive. There are at least six tanks labeled Exxon/Mobil additive, Texaco additive, Chevron additive, etc. Every trucks get the same fuel and a certain amount of the appropriate additive. All the oil companies work together this way around the country. All gas stations near a Chevron terminal gets Chevron gasoline. Only the additives change. Think about it. It makes sense for the companies to work together this way so they all don't have to have terminals in every geographic location. The fuel is the same no matter which station you get it at. Only the detergent additive is different.
2) I think most people buy diesels in an effort to save in transportation costs. I drive 140 miles (round trip) to work each day. I bought a diesel to reduce my costs. The only low cost (practical) ways to prevent CBU is to install a catch can and/or eliminate the EGR. I don't want to bypass my pollution prevention devices. However, I would prefer that my car runs. So far I have not blocked my EGR because this will effect the NOx and therefore the SCR system that injects the urea mixture. I am waivering on blocking the EGR because I don't see any cost effective alternative.
3) I still wait for someone to learn to code out the EGR and charge a reasonable fee for this service. I don't want a performance tune that creates new problems. I don't want to spend thousands of dollars to have a dependable car. Any modification I make must be cost effective and increase reliability.

I agree, for the most part, on your 2nd point regarding purchasing to save on transportation costs.

I also respect your desire to keep the "pollution prevention" devices in tact. However, the EGR plays a crucial role in successful DPF regeneration. I monitored dozens of regens on my car, and the EGR basically closes off (0% requested) to start the process. However, the EGR opens as load increases and it opens to control the upper exhaust temperature limits.

I believe by blocking off the EGR on a 335d with all other emission controls in tact you run the risk of allowing the exhaust temps to exceed the limits. In turn, this would result in Unsuccessful Regenerations, which could result in clogged DPF, which could result in more frequent Regenerations that won't be successful either. All this leads to higher fuel usage and potentially higher carbon emissions than a tuned 335d.

I honestly think that it's either all or nothing when it comes to the emissions equipment on this car.

[Hoooper]

Originally Posted by RollingCoal

I believe by blocking off the EGR on a 335d with all other emission controls in tact you run the risk of allowing the exhaust temps to exceed the limits. In turn, this would result in Unsuccessful Regenerations, which could result in clogged DPF, which could result in more frequent Regenerations that won't be successful either. All this leads to higher fuel usage and potentially higher carbon emissions than a tuned 335d.

I honestly think that it's either all or nothing when it comes to the emissions equipment on this car.

I had blocked egr only from about 60k to about 120k without a dpf clogging issue. If it was going to be a problem it should have shown up in that amount of time.

[QUIKDZL]

Originally Posted by lnxguy

Have you actually pulled the intake and done a visual?

No, I've never had a reason to do so. I'm sure it doesn't look new inside, but everything works properly and she runs great. My dyno graph is posted on the site--see for yourself.

[lnxguy]

Originally Posted by QUIKDZL

No, I've never had a reason to do so. I'm sure it doesn't look new inside, but everything works properly and she runs great. My dyno graph is posted on the site--see for yourself.

You might be surprised at what you find, lol.