I have a 93 190E 2.6 L. I have changed the spark plug for cylinder # 3 three times in the past 4 months. The first time I replaced it I found out the ceramic on the Bosch platinum plug to be chipped.I think it got too hot. The second and third times after I got the original plugs from the dealer, both had a LOT of carbon build up bridging/filling the gap. Cleaned the plug with a wire brush and put back. The car drives Ok now!!However, I feel that it's running rich. The car hesitate when it starts in the morning for a second then idles fine. some times I get this on a hot start. I am thinking that injector # 3 is leaking! or the cold start valve is leaking, but why plug # 3 if the CSV is leaking. Any ideas!
Thank you all.
PS. I avoid using gas with alcohol as much as I can.