Mis fire and Check Engine Light on 2005 Mercedes-Benz SL600

From time to time right after starting, the engine begins mis-firing and the check engine light comes on. I took to local Mercedes dealership and their equipment showed a mis fire on 1, 4, and 5. We replaced the plugs and a few days later the problem has returned. If I turn the vehicle off and immediately back on, the mis-fire goes away (Check engine stays on). This vehicle is in excellent repair overall and I have done all the typical maintenances etc. What could possibly cause this after replacing the plugs???????

by in Wexford, PA on April 24, 2011
1 answer 2 comments
ANSWER by on April 24, 2011
If the spark plug gap were incorrect or the plugs got "dropped" it is possible that the plugs are the problem. Check the electrical connections at the coils are tight and fully seated.
COMMENT by on April 24, 2011
We changed the plugs and the exact problem still exist.
COMMENT by on April 26, 2011
these cars use a central ignition coil for each cylinder bank, one left and one right. inside this "rail" are six coils, but it is sold only as an assembly ($1250 each!!) when you do you own repairs, no one, especially the dealer will give you all the information that you really need.