This is not a plea for help as it has been fixed, just a heads up on cause and effect.
The ignition coils on these engines are different from the #1 and #2 side with different part numbers and have a pair of transistors inside the units that control primary winding charging and field collapse to induce current into the secondary winding to fire the plug. If you have an engine that is over 400 hours chances are pretty good that these transistors are weakening and intermittently failing. This can be evidenced by harder starting, seemingly down on power a bit, and sensitivity to throttle that causes a rapid drop in RPM from higher throttle settings as power is reduced. Eventually one or the other coil will really begin to fail, usually at operating temperature and you'll be running on one cylinder....which isn't a 50% decrease in power but more like a 70% what with pumping and friction losses.
And consider that these coils actually fire every revolution (lost spark) thus running them for 480 hours at 3300 RPM will produce 93+ million spark events per coil, only half of which do actual, useful work. That's 55 times a second.
Also, the cables attached to these coils are carbon track type...just a string impregnated with carbon powder to conduct the spark voltage/current to the plug. I've run across cables that have voids with no string and just carbon powder in the channel that, over time, had vibrated the carbon out of the channel and caused a spark gap. And the OEM plug caps were a fold over, pronged piece of metal designed to puncture the outer sheath and make contact with the carbon string. Really cheap to manufacture but just as cheap reliability wise in terms of actually making good contact.
Just things to think about when your engine isn't performing the way it used to when new.
The ignition coils on these engines are different from the #1 and #2 side with different part numbers and have a pair of transistors inside the units that control primary winding charging and field collapse to induce current into the secondary winding to fire the plug. If you have an engine that is over 400 hours chances are pretty good that these transistors are weakening and intermittently failing. This can be evidenced by harder starting, seemingly down on power a bit, and sensitivity to throttle that causes a rapid drop in RPM from higher throttle settings as power is reduced. Eventually one or the other coil will really begin to fail, usually at operating temperature and you'll be running on one cylinder....which isn't a 50% decrease in power but more like a 70% what with pumping and friction losses.
And consider that these coils actually fire every revolution (lost spark) thus running them for 480 hours at 3300 RPM will produce 93+ million spark events per coil, only half of which do actual, useful work. That's 55 times a second.
Also, the cables attached to these coils are carbon track type...just a string impregnated with carbon powder to conduct the spark voltage/current to the plug. I've run across cables that have voids with no string and just carbon powder in the channel that, over time, had vibrated the carbon out of the channel and caused a spark gap. And the OEM plug caps were a fold over, pronged piece of metal designed to puncture the outer sheath and make contact with the carbon string. Really cheap to manufacture but just as cheap reliability wise in terms of actually making good contact.
Just things to think about when your engine isn't performing the way it used to when new.
nicely done sir!
