Abstract: A fuel injection control system including an ECU, for an internal combustion engine which is capable of changing a valve overlap period by changing a cam phase. The ECU calculates a cam phase difference between the present value and the immediately preceding value of the cam phase (amount of change in the valve overlap period), calculates a wall surface temperature of intake ports, and sets a basic fuel injection time period based on an intake pipe absolute pressure and an engine rotational speed. The ECU also calculates a final fuel injection time period by correcting the basic fuel injection time period according to the cam phase difference and wall surface temperature of the intake ports.

Abstract: There are disclosed a fuel injection control system, a fuel injection control method, and an engine control unit for an internal combustion engine, which are capable of accurately controlling a fuel injection amount according to changes in a valve overlap period due to changes in a cam phase, thereby ensuring proper engine performance. The fuel injection control system for an internal combustion engine which is capable of changing a valve overlap period by changing a cam phase includes an ECU. The ECU calculates a cam phase difference between the present value and the immediately preceding value of the cam phase (amount of change in the valve overlap period), calculates a wall surface temperature of intake ports, and sets a basic fuel injection time period based on an intake pipe absolute pressure and an engine rotational speed.