2009 E63 W211 slight miss
 

I have an '09 E63 and have a subtle roughness at idle. When I accelerate from a stop, it is noticeable for the first second or two, then not really noticeable thereafter to the average person. I brought it to Speed Sport Tuning in Danbury, Ct (excellent German car tuning and race prep shop) and they checked everything and it is not blowing any codes. Any thoughts from the community are appreciated. Rob

The transmission and motor mounts in good shape? I replaced my mounts for the euro type, and now it feels like the car is missing because of the vibration. Funny how a bad tranny mount can send vibrations up into the cab.

How many miles on the vehicle and when is the last time the spark plugs have been changed? Sounds like a failing ignition module(s). Very simple to diagnose and having owned an '07 E63 that developed a misfire, I can tell you it will not throw a code. Download the TorquePro app (last I checked, it was like $5) and get a matching ELM bluetooth dongle (about $12 on Amazon). Drive the car around for a bit and then connect it to the app and run the "Test Results" section. It will tell you overall misfire events and misfire events for each drive cycle, for each individual cylinder. You will know if one is going bad because the numbers will be much higher than the other cylinders. Individual coils are ~$45 on Amazon. Undo the electrical connector, remove two screws and just pull it straight out. May have to twist it from side to side to loosen it up from its grip on the spark plug. Installation is the reverse of removal. Easy peasy. You may have more than one going bad so again, compare the misfire events for each cylinder.

I made a post about it with screenshots explaining this so if you can find it by searching my posts, that will help. I tried to locate the post but am getting an error on the site ATM.