# 335d rough idle



## roadtonow2 (Oct 23, 2011)

Hi all,
I own a 2010 335d with ~ 30,000 miles. I have had all maintenance done by the local BMW dealership. I have noticed over the past few months that the car seems to be idling rougher than it used to. 

Has anyone else experienced this? It doesn't matter if the engine is cold, warm, or hot, there is a slight vibration felt throughout the car. When moving, the vibration is gone.

I'm wondering if this is just due to age - almost 2 years or if there may be something wrong!


----------



## Snipe656 (Oct 22, 2009)

Has the fuel filter ever been replaced? Should been every other oil change but seems to not be the case for many.


----------



## DC-IT (Sep 27, 2009)

Today my D's engine seems to run rougher than normal (noisier) 'cos it -14C here in Toronto with wind chill more like -20C. But the idle rpm was still like 6~700 RPM!

I do note that inside the cabin the engine noise is quite pronounced if the radio/music is switched off. Guess it's not such a luxury class vehicle after all!
By contrast my ML is almost tomb like and very comfortable!

BTW, my fuel filter was only changed at the third oil change.

Despite the noise the D still pulls like a bull!


----------



## Snipe656 (Oct 22, 2009)

Let's put it this way by 30k miles I have replaced by the primary and secondary fuel filters on my truck twice and emptied the water seperator a couple times(excluding the times with the filters). So if I had a rough idle at 30k and original fuel filter then that is where I'd start if self diagnosing. Plus I remember someone with a rough idle and saying it was because fuel filter was never replaced.


----------



## SpeedyD (Sep 18, 2011)

roadtonow2 said:


> Hi all,
> I own a 2010 335d with ~ 30,000 miles. I have had all maintenance done by the local BMW dealership. I have noticed over the past few months that the car seems to be idling rougher than it used to.
> 
> Has anyone else experienced this? It doesn't matter if the engine is cold, warm, or hot, there is a slight vibration felt throughout the car. When moving, the vibration is gone.
> ...


Mine had the same issue at 35k miles. It was rough at idle and slightly rough accelerating from a stop but was fine above 700 RPM. It has been in the shop for 3 weeks now, still no fix....PUMA case opened but no luck so far. They replace fuel injector that fixed part of the issue but not completely. The SES light also lit up eventually. Still waiting on it.....ugh.


----------



## roadtonow2 (Oct 23, 2011)

Hi All,
The fuel filter was replaced at second service.

There is no roughness during acceleration, even light.

It is only during idle. I would say that it is a slight vibration, not a huge deal, but certainly something that wasn't there before.


----------



## Alpine300ZHP (Jan 31, 2007)

roadtonow2 said:


> Hi All,
> The fuel filter was replaced at second service.
> 
> There is no roughness during acceleration, even light.
> ...


How about your cetane? Are you running premium diesel or Chevron? If not, that could be a contributing factor. My understanding is the cetane level is important if it is really cold or hot out.


----------



## AutoUnion (Apr 11, 2005)

Two things:

1. diesels are noticeably louder and rougher in cold weather starts. They quiet down after warming up
2. diesels tend to get louder as the miles pile on


----------



## Snipe656 (Oct 22, 2009)

AutoUnion said:


> Two things:
> 
> 1. diesels are noticeably louder and rougher in cold weather starts. They quiet down after warming up
> 2. diesels tend to get louder as the miles pile on


And that is why I call them rod knockers ...


----------



## Flyingman (Sep 13, 2009)

Guys, the colder engine will have late ignition causing a bit more knocking noise and perhaps some rougher idling. Once jacket water/cooling water gets warmed up and cylinders are warm, it will all be good.

This is normal for a diesel.

On the big marine diesels we have to keep the jacket water at 40 deg C or the engine won't be allowed to start up at all.


----------



## windammer (Oct 30, 2010)

Mine too and I am in Scarborough. Also go to Entras for service. Like them alot. I usually hang with the techs while they work on the car. Never been concerned with what they were doing or how. They know the diesels.
Certainly the colder weather and the winter formula fuel has something to do with ithe more growly sound. My Jeep diesel is the same. They take longer to really warm up too The D still goes like hell



DC-IT said:


> Today my D's engine seems to run rougher than normal (noisier) 'cos it -14C here in Toronto with wind chill more like -20C. But the idle rpm was still like 6~700 RPM!
> 
> I do note that inside the cabin the engine noise is quite pronounced if the radio/music is switched off. Guess it's not such a luxury class vehicle after all!
> By contrast my ML is almost tomb like and very comfortable!
> ...


----------



## DC-IT (Sep 27, 2009)

windammer said:


> Mine too and I am in Scarborough. Also go to Entras for service. Like them alot. I usually hang with the techs while they work on the car. Never been concerned with what they were doing or how. They know the diesels.
> Certainly the colder weather and the winter formula fuel has something to do with ithe more growly sound. My Jeep diesel is the same. They take longer to really warm up too The D still goes like hell


Hi Windammer. I used to lived in Scar from '88~'10 then moved to Ajax in '10 and Endras is just 6~8 mins away.
I'm looking forward to testing the F30 when it arrives.
Maybe we can do a joint test drive on a Saturday?


----------



## cssnms (Jan 24, 2011)

roadtonow2 said:


> Hi All,
> The fuel filter was replaced at second service.
> 
> There is no roughness during acceleration, even light.
> ...


Might be related to your EGR valve. Try disconnecting the vacuum hose and plugging it up with a screw and see if the roughness goes away. If so, it's safe to assume it's EGR related.


----------



## windammer (Oct 30, 2010)

DC-IT said:


> Hi Windammer. I used to lived in Scar from '88~'10 then moved to Ajax in '10 and Endras is just 6~8 mins away.
> I'm looking forward to testing the F30 when it arrives.
> Maybe we can do a joint test drive on a Saturday?


Sounds like a plan to me.:thumbup:


----------

