Fuel injection control method and device for internal combustion engine

A fuel injection control device for an internal combustion engine comprising:

• a fuel pump that pressure-feeds fuel;
• a fuel injection valve that injects the fuel pressure-fed by the fuel pump directly into a cylinder of the internal combustion engine;
• a fuel pressure detection device that detects a pressure of the fuel pressure-fed by the fuel pump;
• and
• a control device;
• wherein:
• the control device is configured to execute:
• a first smoothing process of performing a smoothing process on a detected fuel pressure by first smoothing,
• a second smoothing process of performing a smoothing process on the detected fuel pressure by second smoothing different from the first smoothing, and
• a selection process of selecting, based on an operating state of the internal combustion engine, whether to execute fuel injection control based on a first detected fuel pressure smoothed by the first smoothing process or fuel injection control based on a second detected fuel pressure smoothed by the second smoothing process;
• and
• the second smoothing process is:
• an average value calculation process of calculating an average value of a plurality of fuel pressures detected during one cycle time correlated with a discharge interval of
• the fuel pump, or an average value calculation process of calculating an average value of a plurality of fuel pressures detected during one cycle time correlated with an injection interval of the fuel.