Good Afternoon, thought I would post my latest issue with my 2008 ML350. Started running real rough and immediately gave a check engine light . Drove home and scanned the system read P0300 and multiple P0306. Read up on the codes on the forum, lot of good info. Read that a continuing misfire will cause the ECM to shut fuel to the misfiring cylinder (thats good) and that it is usually the sparkplug or the coil. As I read, I trouble shot by switching the coils between 6 and 4 and pulled the plug to get a read. Plug was really worn gap > .060. Went out and got a new plug then started the car after clearing the code (ICARSFT MBII). Immediately started misfiring and logged a new code P0304 just as hoped for. Also although worn all six plugs looked perfect.
At 120000 miles with what appear to be the original plugs I order a full tuneup kit consisting of 6 plugs 6 coils and 2 air filters. It took about 1.5 hours to install everything and button it up. WOW what a difference a tuneup made. Purrs like a kitten.
Thanks everyone for the information you all share on this forum. It really helps a new first time MB owner out.
//Greg