Date registered: Oct 2012
Vehicle: 1968 250S, 1991 300se, 1998 SL500, 1977 450SEL 6.9. Past MB's; 300SD, 300E, 300TE, 190E, ML420
Mentioned: 9 Post(s)
Quoted: 444 Post(s)
"I began unplugging the distributor lines and saw that cylinders 1,2,3 were firing but 4,5,6 were not."
This could be interpreted 2 different ways. The literal interpretation is that the spark plugs are not firing.
The other is that there was no noticeable difference in how the engine ran when disconnected, but that is not definitive as to the cause.
We all know the first 2 thing when diagnosing are 1. is there spark, 2. is there gas.
At this point we dont know either.