Control device for an internal combustion engine

Abstract

The present invention controls ignition timing appropriately while an increment correction of the fuel injection amount is implemented. A control device of the invention determines a retard angle based on a difference between a prior increment factor, which is determined prior to an actual increment of the fuel injection amount in response to loading of the engine and an OTP fuel increment correction factor for determining the actual increment of the fuel injection amount. The engine load may be determined by intake air quality and rotating speed. When the increment correction is delayed for a fixed time period, the structure of the invention effectively prevents the ignition timing from being retarded excessively due to frequent knocking at the beginning of the delay time. This accordingly prevents the ignition timing from being maintained in the retarding condition to undesirably lower the power of the engine when the delay time has elapsed and an actual increment of the fuel injection amount has been executed. In the ignition timing control of the invention, an increase in retard angle immediately affects the ignition timing control while a decrease in retard angle slowly affects the ignition timing control. This allows the ignition timing to be controlled appropriately without undesirable delay.