Method for detecting combustion misfires in an internal combustion engine

Abstract

The invention relates to a method for combustion misfire detection in multi-cylinder internal combustion engines. In the method, rough-running values for each cylinder of the engine are determined individually for each crankshaft rotation by measuring the segment times. The segment times include the times corresponding to the piston movement of each cylinder to be measured during which times the crankshaft passes through a corresponding circular segment angular region and, on the basis of filtered rough-running values, equalization or corrective factors are computed for each cylinder in an evaluation unit for influencing injection times or injection time points of each individual cylinder. The determined rough-running values (LUT) or the filtered rough-running values (FLUT) are compared in a desired value comparison to a threshold value (SW2) which is pregiven in value significantly less than the threshold value (SW1) for misfire detection. A reduction of the threshold value (SW1) for misfire detection to a lower level is effected by the continuous dropping below the second threshold value (SW2) within a pregiven time interval (Δt) or during a specific number of engine revolutions (Δu).

Dependencies are inferred from the claim text.