Abstract: A method and apparatus of developing a stabilized power firing event signal for a cylinder in a wasted spark ignition system having pairs of complementarily connected cylinders, each with a spark plug connected to an opposite end of an independent ignition coil. The first and second firing event signals are developed for each spark plug upon firing of the ignition coil. The first and second signals are combined with like polarity in a summation circuit for eliminating common mode signal portions. The combined signal, which is now stabilized and accurately indicates spark duration, is used for capturing secondary ignition data and may be visually displayed for analysis.

Abstract: A method of determining the cylinder #1 power firing event in a wasted spark ignition system comprises developing a first signal comprising the integration of all power firing event signals, a second signal comprises the integration of all wasted firing event signals and comparing the amplitudes of the two signals to determine which represents the power firing events. The firing event signals are sorted for integration based upon knowledge of the polarity of spark plug firings, the cylinder firing order and the occurrence of a #1 cylinder firing event signal.