Do You Know Modern Ignition Systems

In modern systems, the distributor is dispensed with and replaced by electronically controlled ignition. Much smaller coils are used, one coil per spark plug, or one coil for two spark plugs (e.g., two coils in a four-cylinder engine, or three coils in a six-cylinder engine). A large ignition coil goes out by about 40 kV, while a small lawn mowing coil (e.g. a lawn mower) goes out by about 15 kV. These coils can be mounted remotely or placed on top of a spark plug, called direct ignition (DI) or coils on a plug. One coil for two spark plugs (in two cylinders) is through a wasted spark system. In this arrangement, the coils produce two sparks to the two cylinders per cycle. The fuel in the cylinder near the end of its compression stroke is ignited, while the spark in its companion near the end of its exhaust stroke has no effect. Wasted spark systems are more reliable than single-coil systems with distributors and cheaper than plug-and-play coils.