Patent ID: 7729846

Claim:
A control device for an engine comprising: an air-fuel ratio detector detecting an air-fuel ratio of an exhaust gas of the engine, the engine capable of using mixed fuel including alcohol; a feedback controller performing a feedback control of an amount of a fuel injection of mixed fuel including alcohol so that the air-fuel ratio detected by the air-fuel ratio detector is come close to a target air-fuel ratio, the mixed fuel supplied from a fuel feeder; a concentration estimator estimating a concentration of the alcohol in the mixed fuel based on the air-fuel ratio of the exhaust gas and a correction amount for the amount of the fuel injection controlled by the feedback control; and a malfunction determiner determining that the fuel feeder has a malfunction when the correction amount is greater than or equal to a value for a period which is longer than a first period in a second period, the second period which is from a first time point when the feedback controller starts to perform the feedback control.