[Xipher]

Hey all, my '09 335d is at about 85,000km and has developed quite the rough idle over the last few weeks. No codes as of yet, but I can definitely feel it while idling at a stop light or under light acceleration.

I'm guessing this is a classic case of CBU, and I've been looking into getting it cleaned out, or potentially doing it myself, although I'm still a little wary about doing it.

So questions are:
1) Is there an easy way to check to see how bad the CBU is, without pulling the manifold (I figure if I get to that point I might as well clean it myself)

2) Anyone in the Vancouver area have the cleaning done at a dealer, indy, or have done it yourself and have any experiences to share?

Thanks

[Yozh]

Originally Posted by Xipher

Hey all, my '09 335d is at about 85,000km and has developed quite the rough idle over the last few weeks. No codes as of yet, but I can definitely feel it while idling at a stop light or under light acceleration.

I'm guessing this is a classic case of CBU, and I've been looking into getting it cleaned out, or potentially doing it myself, although I'm still a little wary about doing it.

So questions are:
1) Is there an easy way to check to see how bad the CBU is, without pulling the manifold (I figure if I get to that point I might as well clean it myself)

2) Anyone in the Vancouver area have the cleaning done at a dealer, indy, or have done it yourself and have any experiences to share?

Thanks

If you have ISTA, there is test plan to check for CBU. One friend has done CBU st BMW Langley for $700. Before that, you may wish to just pull off EGR and take a peek at the valve itself and inside the manifold. But rough idle may not necessarily be due to CBU. It may be a glow plug controller (if at start up), could be MAF, fuel filter or an O2 sensor (unlikely). May wish to pull shadow codes if any. That may give you an early indication.

[temporaptor]

http://www.e90post.com/forums/showthread.php?t=1195370
CBU test

[OmahaDZL]

My rough idle was injector related.......but ya gotta pull the manifold to take out the injectors anyway

Id say in owning a 335d, you should get familiar with pulling the manifold anyway....Ive done it .....maybe 4 or 5 times now....

[Xipher]

Thanks all, yeah after thinking about it a little more, I'm more inclined to think it is injector related given the way it feels.

Is it possible to clean the injectors, or do they just need to be replaced? And how does the DDE factor into it, as it seems like in some cases that's been the more of a cause of the issue rather than the injectors themselves?

[Owen81]

Could also be a vacuum issue related to the motor mounts.

[OmahaDZL]

Originally Posted by Xipher

Thanks all, yeah after thinking about it a little more, I'm more inclined to think it is injector related given the way it feels.

Is it possible to clean the injectors, or do they just need to be replaced? And how does the DDE factor into it, as it seems like in some cases that's been the more of a cause of the issue rather than the injectors themselves?

Im not sure what you mean by rough idle caused by the DDE.... just not sure what you are referring to. I have not found that to be the case in any situation I have encountered with mine. When you put in a new injector the DDE has to be coded for the new injector, but thats the only reason I can think of....otherwise the DDE will try to compensate FOR a rough idle by changing fueling to other injectors.....

As for fixing it, some will tell you that you can run some stiction reducer or diesel injection cleaner through and it will clean it right up, but that definitely didnt work for my issues....... so "could" it fix it?....yes...it could... but I wouldnt bet on it... it is the cheapest solution by far though.....

Otherwise...consult these two threads:
http://www.e90post.com/forums/showth...ight=injectors

http://www.e90post.com/forums/showthread.php?t=1346239

[Xipher]

I got the P02D0 - Cylinder 3 Fuel Injector Offset Learning At Min Limit code this morning, so I guess it was the injectors (or at least one of them) after all.

[dmanb2b]

Do yourself a favor. I had same code for cylinder 2 and 4 about 6 months ago. I am not saying it isn't your injector or CBU, but I ran and continue to run Hot Shots diesel extreme fuel system treatment. The code has not re-appeared since and the injectors are noticeably quiet. I will likely switch to archoil next.

[taibanl]

Originally Posted by Xipher

Thanks all, yeah after thinking about it a little more, I'm more inclined to think it is injector related given the way it feels.

Is it possible to clean the injectors, or do they just need to be replaced? And how does the DDE factor into it, as it seems like in some cases that's been the more of a cause of the issue rather than the injectors themselves?

BG 245 on amazon

[Blown284]

What ended up being the issue? Injector? Did the fuel cleaner help?