>hmm. no. the car has to fire both 2 and 3 or 1 and
>simultaneously. there is no way to retard 1 cylinder at a
>time without retarding both, wether it be while one is on
>compression stroke and one is on exhaust stroke or vice
>versa. both fire at the same time. that is why there are
>only 2 trigger wires on our coil packs.

Yes, true, let me explain how the J&S retards per cylinder>

Ok, let me explain this a little more, using how the J&S retards spark on and per cylinder basis. Yes, cylinder 1 and 4 share the same coil/ and spark as does cylinder 2 and 3. Both sets fire sparks at the same time. If cylinder 1 is on the compression stroke, then cylinder 4 is on the exuast stroke. So cylinder 1 fires, as does cyinder 4. Power is made by the spark in cylidner 1 because its on the compression stroke. Spark is wasted in cylinder 4, since its on the exaust stroke. NOW, lets say when cyl 1 fired, it detonated. The J&S knows this cyl detonatied becuase the sensor read the knock, and it knew which coil trigger wire just fired. Now the unit will retard cylinder 1 NEXT TIME IT FIRES. The J&S knows that we have 2 coils. The unit knows that the exact next cylinder to be fired from the cyl 1 coil is cyl 4. So it SKIPS this trigger signal, and waits for the next trigger signal, and THEN it retards that signal, which is cyl 1. Make sense?? So we can retard on a per cylinder basis.