How do you check to see if a coil on plug ignition, like a 5.4 truck is firing a plug, since you can't just clip a timing light around the plug wire anymore?
This is really for a Yamaha Waverunner, that I can't scan (yet).
id say that the easiest way for you do a quick check would be goin out and buying a "HEI plug tester" it is a "fake spark plug" and fits between the plug and the coil. you fire the engine up and look through the clear plastic to see the spark and pay attention to what color the spark is. blue is good yellow is weak.
you can pick one of these tools up at a cheapie tool store for like 3 bucks or a snap-on truck for like $1,000,000. they both do the same thing.
there is a wand looking device that you can place against the coil and it will tell you if the coil is firing and how strong the firing is..
at work I use the IDS/WDS scan tool, it has attachments for a ignition test where there is little clips that fit against the coil and it tells you how strong the coil is firing.