Fuel injection control method for a multi-cylinder internal combustion engine, having a fail safe function for abnormality in cylinder-discriminating means

摘要

A fuel injection control method for successively injecting fuel into a plurality of cylinders of an internal combustion engine in predetermined sequence in synchronism with pulses from top-dead-center detecting means which are successively generated immediately after generation of each pulse from cylinder-discriminating means. The method is adapted to perform a fail safe function in the event of occurrence of an abnormality in the cylinder-discriminating means. The number of pulses is counted which are successively generated from the top-dead-center detecting means immediately after generation of each pulse from the cylinder-discriminating means. If no further pulse from the cylinder-discriminating means is detected until the count of pulses from the top-dead-center detecting means reaches a number equal to the sum of the number of the engine cylinders and while the rotational speed of the engine is higher than a predetermined value, the cylinder-discriminating means is regarded as abnormal. Then, injection of fuel into the cylinders is effected in the above predetermined sequence in synchronism with pulses from the top-dead-center detecting means alone, irrespective of generation of subsequent pulses from the cylinder-discriminating means.