I've noticed when the car sits overnight during part of the cold start cycle the engine idle gets a bit "lumpy" which kind of shakes the car a bit every few seconds or so then after a minute or two it idles very smoothly; is this normal with the 55?

Thanks

 

mine does the same thing - even before and after the K2 upgrade....

 

Thanks! I feel alot better Is that a long or short hair Jack Russell in your avatar?

 

Diddo, mine also has a rough idle until warm-up!

 

Mine does the same thing...

 

Same with my car, so i let it idle until the temperature guage reaches a couple bars under the half line bar.

 

You can thank CARB for your cold-start symptoms. Cold engines are set to run lean until the cat fires off. A lean-running engine will idle roughly.

 

Mine does the same thing and never smooths out. But that's normal considering i'm running a set of K cams.

 

Thanks for all the feedback.

The reason I noticed this is I always let my cars idle down after a cold start before driving off; I've just never had one shake it up like this before. I also haven't heard of this problem with 2006 500's, 350's etc; maybe it's a 55 thing? If it is a 55 thing should n't MB provide a flash update for the ECU. Aren't cars allowed to run richer during the cold start cycle?