How rough is rough idle?

[Joshua Harrington]

Hi all,

First time poster, but found this forum thoroughly useful in the past. Thanks for all your help!

I have owned my first Mercedes for a couple of months now and naturally im in love with it already.

Just a niggle though- the idle is not perfectly smooth. It only jumps around about 20rmp each way, but my only experience driving diesels is double decker busses. Probably not a fair comparison!

Is this normal for these cars, or should I look into the dreaded injector replacement?

The car is a W204 C Class 2013 60k miles, and I got the impression that the injector problems had been ironed out. It has a full MB service history and seems very well looked after!

If I'm being paranoid I apologise. I couldnt find anything on the forum about what constitutes a rough idle, and the car is otherwise perfect with good power delivery!

Thanks.

 

[Larkone]

Engine mounts? - common failure on MBs

 

[A.J.]

Hi Joshua, welcome to the forum

 

[mattkh]

.....It only jumps around about 20rmp each way,....
Thanks.

Can you see a 20rpm variation on the needle in the rev counter?

 

[Botus]

find another owner and compare to theirs

 

[malcolm E53 AMG]

Could be injector tip wear or slightly low fuel rail pressure but unless it starts misfiring I wouldn’t bother about it, might be worth putting some fuel additive/cleaner through it with the customary Italian tune-up

Might be worth changing the fuel filter