ROTATIONAL FLUCTUATION MALFUNCTION DETECTION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To ensure the sufficient number of opportunities to determine the presence or absence of "malfunction" in a lean imbalanced state based on rotational speed fluctuation, and to precisely detect the "malfunction", in a vehicle equipped with an idle stop function during the stop of the vehicle.SOLUTION: This rotational fluctuation malfunction detection device for an internal combustion engine determines that a rotational fluctuation value is "normal" when the rotational fluctuation value obtained in a "disturbance fluctuation state" with rotational speed affected by disturbances from a driving wheel is below a threshold L1 (sufficiently small value). If the rotational fluctuation value obtained in the "disturbance fluctuation state" equals or exceeds a threshold L2 (L1, sufficiently large value), the rotational fluctuation malfunction detection device determines that the rotational fluctuation value is "abnormal". When the rotational fluctuation value obtained in the "disturbance fluctuation state" is equal to L1 or between L1 and L2, the rotational fluctuation malfunction detection device subsequently determines that the rotational fluctuation value is "normal" if the rotational fluctuation value obtained in a "non-disturbance state" with no rotational speed affected by the disturbances from the driving wheel is below a threshold L3, and the rotational fluctuation value is "abnormal" if the rotational fluctuation value equals or exceeds L3.