Control method of internal combustion engine

A control method of an internal combustion engine that causes an internal combustion engine including a port injection valve that injects fuel into an intake port and a cylinder injection valve that directly injects fuel into a combustion chamber to selectively execute port asynchronous injection that starts fuel injection by the port injection valve while an intake valve is closed and ends the fuel injection by the port injection valve before the intake valve opens, port synchronous injection that starts fuel injection by the port injection valve while the intake valve is closed and ends the fuel injection by the port injection valve while the intake valve opens, and cylinder injection that performs fuel injection by the cylinder injection valve,

• wherein when request torque to the internal combustion engine is in a first torque range, lean combustion in which fuel is leaner than stoichiometric combustion is realized by the port asynchronous injection,
• when the request torque increases from the first torque range to a second torque range that is higher than the first torque range, fuel injection is switched to the port synchronous injection from the port asynchronous injection, and lean combustion is realized by the port synchronous injection, and
• when the request torque increases from the second torque range to a third torque range that is higher than the second torque range, the port synchronous injection is stopped, and lean combustion is realized by the cylinder injection.