# What are the symptoms for 335d carbon buildup?



## bimmerup-sonny (May 29, 2013)

Hi,

My '11 335d with 59K miles shows some engine stutturing, is this
an early sign of carbon buildup?

I also have the BTD adapter, I will take it out and see if that is the culprit.

In genneral, what are the symptoms for carbon buildup?

thank you


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## Hoooper (Jun 17, 2013)

rough idle, bad mileage, weak power. Rough idle and lower mileage being the most obvious


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## bimmerup-sonny (May 29, 2013)

Hoooper said:


> rough idle, bad mileage, weak power. Rough idle and lower mileage being the most obvious


I don't notice the bad mileage, but the rough idle gradually getting
rougher. I also have the JBD installed, will take it out this weekend.

What is the latest news on carbon buildup cleaning?
How much does it cost from dealer, and any shop in Socal that 
forum members have used and reccommended for this service?

Thank you


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## KeithS (Dec 30, 2001)

Poor mileage is the most prominent effect of CBU. I had zero symptoms of CBU until the SES light came on at 53K miles EXCEPT lower MPG. Then I had some occasional rough idle. Although I had an extended warranty, I believe it was actually covered under the factory warranty. But no dealer will do anything as warranty until the SES is on.

If you get an honest dealer who knows what they are doing, and your paying, it should be in the order of $1500 for cleaning.

For me the improvement in MPG was very noticeable after the cleaning. The diesel growl was a little louder and while improvement in power, it was not that much. My DEF usage also went down a lot due to better MPG plus I believe when they updated the DDE program the parameters were changed to use less DEF. It's been over 16K miles since last filled and no DEF warning yet.


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## bimmerup-sonny (May 29, 2013)

KeithS said:


> Poor mileage is the most prominent effect of CBU. I had zero symptoms of CBU until the SES light came on at 53K miles EXCEPT lower MPG. Then I had some occasional rough idle. Although I had an extended warranty, I believe it was actually covered under the factory warranty. But no dealer will do anything as warranty until the SES is on.
> 
> If you get an honest dealer who knows what they are doing, and your paying, it should be in the order of $1500 for cleaning.
> 
> For me the improvement in MPG was very noticeable after the cleaning. The diesel growl was a little louder and while improvement in power, it was not that much. My DEF usage also went down a lot due to better MPG plus I believe when they updated the DDE program the parameters were changed to use less DEF. It's been over 16K miles since last filled and no DEF warning yet.


I had a hard time maintaining idle when I started the car last night after work.
My SES light just came on as I drove home last night while going up hills

You said it is covered under Factory Warranty but yours was at 53K miles?

I don't see any MPG reduction, so I suspect it was not carbon build up,
so this morning I just took out the JBD... well I started the car right up, and let it idle
for 10 mins, and the rough idle is gone, and the SES light is also gone
after a few minutes.

Will drive it today and see if the symptom is gone completely.
I know the carbon build up will come soon, let's hope not too soon 
BTW, minicorsa.com said they can clean it for $600, anyone used them 
for this service before? I had my OEM Performance Suspension installed there, 
and they did a great job


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## bimmerup-sonny (May 29, 2013)

bimmerup-sonny said:


> I had a hard time maintaining idle when I started the car last night after work.
> My SES light just came on as I drove home last night while going up hills
> 
> You said it is covered under Factory Warranty but yours was at 53K miles?
> ...


Update:
I put on 80 miles on Sunday, and today my commute is 30 miles,
so after 110 miles, the car is running without any problems.. no more
rough idle nor starting up issue.

I can say with certainty that the JBD was the culprit, I will see if Burger Tuning
want this bad unit back for their R&D department.


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