Failed spark plug wires and/or ignition coils can cause intermittent misfires (rough running); the Check Engine Light may also illuminate. Diagnoses of the ignition system will be necessary to determine which components are at fault.Google+
Car Problem Reports
Mercedes-Benz CLK55 AMG Bad Spark Plug Wires/Ignition Coils May Cause Misfires and Possible CEL
Mercedes-Benz CLK55 AMG Problem
Average Mileage: 80,000 mi (80,000 mi - 80,000 mi)
At idle the car misfires and shakes the car slightly around 800-1000 RPM. Over 1500 it's not noticeable. I changed the ignition wires and noticed an improvement in HP but the misfires are still there. Will get mechanic to diagnose which coils are faulty and replace for around $75 each. Not sure what the labour will be. Fuel consumption has gone up lately as well. Might be a combination of this coil issue and possibly the Mass Air Flow Sensor. Will update after diagnostics.
misfires check engine light