2011 E63 Inconsistent Idle




I mentioned this issue in another thread but wanted to give it its own thread. Here's the specifics:
Just bought the car 2 weeks ago with 31,000 miles on it.
It has 6 weeks left of factory warranty.
Car had all of its services performed by dealer as scheduled before me.
I have an appointment for Wed to have this idle checked out.
I just know from previous experience with the Benz Dealer that if the problem is not obvious, it doesn't get solved or it get flat ignored.
I am hoping for some true gear heads out there that may know exactly what may be to blame for the issue so I can request certain diagnostics from them.
Example: bad ignition coil, ignition wire, etc. Something I can make sure they check out. OBD did not reveal any trouble codes to give clues. I really just don't want to get shined on until it's out of it's 4 year warranty and into its aftermarket warranty.
It does not seem to be motor mounts. Tried it in drive, N, and Park and vibration does not change. If it were motor mount it usually gets much better when put in N or Park.
I am thinking it is some type of misfire. I did notice that the vibration seems strongest after downshifting and using engine/trans to come to a stop. Almost as if something gets out of whack from the trans breaking. But it still does exhibit off and on even when not stopping via downshifting.
Could this have to do with the wet clutch and not be engine at all? Probably not if it does it in Park and Neutral right?
Any ideas?




Wife feels it. And she has a 2014 GLK350 to compare against.
My private mechanic immediately felt it when I had him inspect the car before I bought it. He still recommended I buy the car based on the deal I was getting and that I could still take it to the dealer to get the idle fixed. He wasnt sure exactly what it might be as no OBD trouble codes came up related to idle. He did think that the dealer guys, with more time, would figure it out though.
Even my 16 year old (yes, I bought that one new) E55 never had idle vibration until she needed a motor mount.




His initial thoughts are that it is not serious and likely only a vacuum leak. He did say they would get it fixed though one way or another.
I will update after I get the car back. Hopefully I will get it before the weekend.




His initial thoughts are that it is not serious and likely only a vacuum leak. He did say they would get it fixed though one way or another.
I will update after I get the car back. Hopefully I will get it before the weekend.
So now that they can't find an easy solution, it is normal? Huh?

So to quantify what I am feeling with the idle, it is not horrible. It is not as bad as when one of my E55 motor mounts went bad for example. It does not fell like a 70's muscle car with a radical cam!
It is simply noticeable. Best way to describe it is imagine you have a bottle of water in the cup holder and while in idle the water at the top is getting small waves.
Does this sound normal? Anybody ever see "rough water" in their cup holder while sitting in P, N, or D?
Maybe I'm nitpicking ?? Maybe a 6.2 litre 518 Hp engine will have a minor wobble?
Mine has been rippling for years, and I love it.
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I went to 3 different MB dealers and one shop foreman went on the test drive with me and felt it too, but when they did their diagnostic check. Dealer says its within Mercedes guildline however I feel something is wrong.
Service department tells me a story that the Mercedes learns your driving pattern and when you drive out of place, the car thinks you want to give more gas so the car jerks when you break. I know it's a messed up excuse, but been to 3 dealers and all tells me the E350 is fine.
I hope I'm on the same page as to your inconsistent idling inconsistent idling issue.
Please keep up updated the outcome. Thanks.




My engine idle issue that was consistantly on and off for the first few weeks of owning her as pleasantly dissapeared!!
Haven't felt in a few weeks now. I am guessing that my harder driving style, than perhaps the previous owner, broke some piece of crud loose that was causing it. Like sparkplug gunk or something.
Now I couldnt be happier with my girl! Love this car!
Just thought I would share.






