Is the internal combustion engine fussy as to what spark is being used? Today's engines are required to run with varying fuel quality, low emission levels and greatly improved fuel economies. To do this, new engine designs and ignition systems have been developed. Some of these engine designs are fussy as to the spark being used.The Echlin Precision Ignition Control or EPIC is a new ignition system with variable spark duration capability. This system was developed to work with engines such as the TCP or TCCS (developed by Texaco) and other lean-burn or fast-burn designs.This paper should answer the question: Does the ignition system make a difference to the engine?