COMBUSTION MISFIRE DETECTING METHOD IN MULTI-CYLINDER INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an accurate combustion misfire detecting method in a mufti-cylinder internal combustion engine. SOLUTION: A determined rotation irregular value LUT or a filtered rotation irregular value FLUT is compared with a threshold value Sw2 which is essentially set to be smaller than a threshold value Sw1 for detecting misfire in a target value comparison step 2.1 in an evaluation unit 2.2. In this case, the threshold value Sw1 for detecting misfire is made low to a smaller level due to the fact that the rotation irregular value LUT or FLUT is always lower than the second threshold value Sw2 within a prescribed time intervalΔt or for a prescribed engine speedΔu period.