Although we kno its Fuel thats cut, A lean spike in the a/f doesnt nessesaraly mean that fuel was cut. it means there was a misfire but the A/F controller couldnt tell you if it was fuel related or spark related.
"can someone tell me why a faulty injector can burn up a cylinder?
and how can running lean on a 4 stroke (as opposed to a fuel-lubricated 2 stroke) cause problems? is it the time of the explosion?"
Its Not only a concern of detonation but also a Lean mixture burns very hot, hot enough to melt pistons. If ONE injector was somewhat clogged and causing AF's about 12.5 or higher at full throttle high boost, there could be enough heat generated to melt pistons and or detonate and Blow holes in the piston. 12.5 is about the safe limit, 12.5 is fast but dangerous, i prefer <12 AF's more like 11.7-11.5
a 2 stroke engine can be damaged from lean mixtures as well but the oxygen content isnt as high in the cylinder due to the design on the engine, they dont breathe as efficient as a 4 stroke. This lowers combustion temps so they have more leeway to lean mixtures because it doesnt burn as hot. Not to mention the oil in the CC as well. well at least AFAIK.
