Bioethanol can be used as fuel substitution for gasoline, with pure fuel or mix with gasoline. The use of gasoline that blend with bioethanol has its effect on engine performance. The amount of bioethanol can affect power, torque, and emission produced by the engine because it has different characteristics with gasoline. As the number of bioethanol in the mixture increase, it will lower the power and torque produced by the engine because bioethanol has lower energy content than gasoline. Nowadays, the engine can be set and controlled by the Engine Control Module (ECM). ECM usually used by car racing teams or off-road racing teams to optimize the engine to its peak performance by power and torque. The way ECM optimize the engine performance is by adjusting the ignition timing and the injection duration of the engine. Injection duration will set the amount of fuel injected by the injector. The objective of this research was to determine the effect of setting the injection duration of the injector to the performance of the engine using E20, E30, and E40 gasoline-bioethanol mixed fuel. The effect of reducing the duration of the injection is the power and torque produced by the engine will increase.