Patent ID: 7540185

Claim:
For use in conjunction with an internal combustion engine having a plurality of combustion chambers and a piston reciprocally disposed in each cylinder, said pistons being mechanically coupled to a rotary crankshaft, a system for detecting one or more engine misfires in one or more cylinders comprising: a processor, a crankshaft sensor which produces an output signal to said processor representative of the angular position of the crankshaft, said processor being programmed to determine a first velocity difference between a first set of angularly spaced angular ranges of the crankshaft and a second velocity difference between a second set of angularly spaced angular ranges of the crankshaft, said first and second set of angular ranges being different from each other and together extending less than one revolution of the crankshaft, said processor generating an engine misfire signal whenever an absolute value of either of said first and second velocity difference exceeds a threshold value.