Abstract: Absolute engine position sensing is provided by monitoring the temporal relationship of energization of multiple spark plugs sharing a common source of drive energy in a direct ignition application. The spark plugs are connected across the source with opposing electrical polarity, and the relative time of discharge across the plugs compared by sensing the time and polarity of high speed transient activity in proximity to the source.

Abstract: An inductive ignition circuit, comprising a secondary winding across a spark plug and a primary winding in series with a lossy transistor switch and a power source, is subject to ringing at the start of the dwell period which can cause premature combustion. Ringing is suppressed by a short switch turn on pulse followed by a short delay prior to the main dwell period, causing a beginning build up of primary current and circuit energy followed by absorption of energy in the switch during switching to dissipate circuit energy needed for oscillation. Preferably, the short pulse is terminated when all the ringing energy is stored in the leakage inductance of the ignition coil.