FUEL METERING CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINE

A fuel metering control system for an internal combustion engine, having a feedback loop. In the system, the quantity of fuel injection (Tim) to be supplied to the engine (plant) is determined outside of the feedback loop. A first feedback correction coefficient (KSTR) is calculated using an adaptive law, while a second feedback correction coefficient (KLAF(KSTRL)), whose control response is inferior to the first feedback correction coefficient is calculated using a PID control law. The feedback correction coefficients are calculated such that the plant output (air/fuel ratio) is brought to a desired value (desired air/fuel ratio). The engine is equipped with a variable valve timing mechanism which switches the valve timing between characteristics for low engine speed and those for high engine speed. If the characteristic for high engine speed is selected, the second feedback correction coefficient is used for fuel injection quantity correction.