Engine control system and method having control routines of different execution priorities

Abstract

An engine control system checks for a misfire from a change in the rotation speed of an engine. A rotation interrupt routine is executed every 30° angular rotation of an engine crankshaft to calculate and store only the rotation speed. In one of a plurality of time interrupt routines which are executed every predetermined respective time intervals, a change in the stored rotation speed is calculated to check for a misfire of the engine. The time interrupt routines have different execution priorities which are lower than that of the rotation interrupt routine. The time interrupt routine for checking the misfire has a non-highest execution priority among the time interrupt routines so that engine control processing such as fuel injection and ignition may be executed in another of the time interrupt routines having its execution priority lower than that of the time interrupt routine for checking the misfire.

Dependencies are inferred from the claim text.