An engine intake system including a main intake passage leading through an intake port to a combustion chamber, an auxiliary intake passage branched from the main intake passage and opened to the intake passage, and a control valve provided in the main intake passage and adapted to be opened under a heavy load engine operation and closed under a light load engine operation. A fuel injection valve is provided in the auxiliary intake passage close to the opening of the intake port to the combustion chamber to inject fuel toward the combustion chamber.