Misfire detection device and control device for direct injection spark ignition engine

摘要

PROBLEM TO BE SOLVED: To detect in good response respectively rich misfire due to displacing to a rich side and lean misfire due to displacing to a lean side of air/fuel ratio around a spark plug relating to optimum air/fuel ratio, and quickly reduce the rich/lean misfire, in a direct injection spark ignition engine. SOLUTION: Secondary voltage (discharge voltage) at ignition time is detected (S1), when misfire is detected (S2), the secondary voltage (discharge voltage) is compared with reference voltage, and by estimating air/fuel ratio around a spark plug, the misfire is discriminated in rich/lean misfire (S3). At rich misfire time, by decrease correcting fuel in the next time, reduction of rich misfire is attained (S4). On the other hand, at lean misfire time, by increase correcting fuel in the next time (S5) or by increasing a current carrying time in an ignition coil, reduction of lean misfire is attained.