Engine misfires (rough running) and lack of power are commonly caused by ignition coil pack or ignition module faults. Proper diagnoses should isolate the cause and prevent unnecessary replacement of good parts.
Car Problem Reports
Mercedes-Benz SL600 Rough Running Motor/Lack of Power Due to Coil Pack/Ignition Module Failure
Mercedes-Benz SL600 Problem
Average Mileage: 39,571 mi (32,000 mi - 47,000 mi)
Visitor, 2005 Mercedes-Benz SL600, 47,000 mi
Check engine light came on, told I need to change coils $2600, now still happening brought it in to another mechanic for diagnosis, told still misfiring in 2 cylinders. Back in the shop now.
had this problem first in 2009 and had the dealer misdiagnose the source and changed all my spark plugs. ( expensive deal on this car)... But that wasn't the problem, apparently! Since then a number of times the check engine light would come up & I would validate with my OBD2 device that it was cylinder 11 misfiring. I took the car to the dealer again who saw BOTH cylinders 11 and 4 misfiring and requiring coil change at a cost of ~ $2k/coil !! If that recurs again I am dumping this lemon...
Visitor, 2004 Mercedes-Benz SL600, 42,000 mi
Very often occurring problem
Visitor, 2005 Mercedes-Benz SL600, 32,000 mi
Visitor, 2004 Mercedes-Benz SL600, 38,000 mi
engine light on, misfire codes for 6 cylinders, turn engine on and off take care of the problem temperary and happen again, now happen all the time.
failure left side misfire. Codes 300, 307,308,--9,10,11,12.