An apparatus, and a corresponding method, for determining misfire in a reciprocating engine operates on a selectable quantity of discrete sampled acceleration signals that are indicative of acceleration behavior of the reciprocating engine. A decimation device selects a quantity of the discrete sampled acceleration signals dependent on an engine family, and optionally engine operating conditions such as speed and load. An accelearation signal is selected from the sampled acceleration signals, preferably the sample having the most negative magnitude. A misfire determination device provides a misfire indication dependent on the selected acceleration signal.