To prevent unsuitable knock control by prohibiting advance control or delay control at igniting, when the determination whether or not knock is occurring in an internal combustion engine or not is unstable.
In a transition period of an operating state of the internal combustion engine, and after controlling for switching a filtered frequency band of SCF(switched capacitor filter), a back ground level is unstable, so that knocking determination by a knocking determining level set on the basis of the back ground level has low reliability. Therefore, during a specified period set by a counter CFCHANGE in a step S302, advance/delay control at igniting by the knocking determination is prohibited in a step S304. During the specified period, an advance/delay position at igniting just before controlling for switching the filtered frequency band of the SCF is kept regardless of the result of the knocking determination. Therefore, a deterioration in the operating state of the internal combustion engine due to unsuitable knock control can be prevented in advance.
YAMADA HIROHIKO
YUKIMOTO HIDEKI
KASASHIMA KENJI
TOYOTA MOTOR CORP