Abstract: An ignition timing control system for an internal combustion engine, for controlling an ignition timing of the engine, is provided. A charging efficiency of the engine is calculated according to the intake air flow rate and the engine rotational speed which are detected, and a knock limit ignition timing is calculated according to the engine rotational speed and the charging efficiency. A knock correction value is calculated according to the knocking detection result by a knock sensor, and a learning parameter table, in which first and second learning parameters are set, is updated based on the engine rotational speed and the knock correction value when the knocking is detected. The learning parameter table is retrieved according to the engine rotational speed, to calculate the first and second learning parameters.

Abstract: A knocking detecting apparatus for an internal combustion engine, which can more accurately perform the knocking determination based on frequency components of the output signal of the knock sensor, is provided. A frequency spectrum analysis of the knock sensor output signal is performed at predetermined angular intervals of the crankshaft rotation angle. Intensities of a plurality of frequency components obtained by the frequency spectrum analysis are stored as time series data. The time series data of the frequency component intensity are binarized, and it is determined whether or not a knocking has occurred based on the binarized time series data.