Misfire discriminating method for engine

摘要

The method of discriminating misfire of any cylinder of a multicylinder engine comprises the steps of discriminating a cylinder number (#i) at a present combustion stroke (S101) . A present momentum is claculated for the present combustion stroke, in a period in which no combustive work is done (S105). A second momentum for a second stroke preceding the present combustion stroke by two strokes, is computered in a period in which no combustive work is done (S106). The present and second nmomentums (S107) are averaged. A momentum is desired for a stroke preceding the present combustion stroke by one stroke, in a period in which no combustive work is done (S107). A difference between the averaged momentum and the momentum (S107) is taken. A misfire judgement level from a map of combustion conditions is set as a function of the momentum and engine load data (S108). The difference is compared with the misfire judgement level (S109).