Air-fuel ratio control system for an internal combustion engine

摘要

An air-fuel ratio control system for an internal combustion engine is disclosed. A basic fuel injection quantity is determined by using a cylinder pressure at a predetermined crank angle, and a signal provided by an intake air temperature sensor as parameters. A compensation fuel injection quantity for an accelerating mode or a decelerating mode is determined on the basis of a predetermined cylinder pressure variation corresponding to the variation of the output of a throttle opening sensor and an engine speed. The air-fuel ratio control system does not need an expensive air flow meter.