Why should you flash tune your ECU on a Yamaha FZ09/MT09? The most obvious issue arises during on-off throttle transitions. During deceleration, the ECU’s fuel cut functionality turns the fuel injectors off above about 4,500 rpm to reduce fuel consumption and emissions. Solution? A reflash of the ECU with a custom-developed engine map. Because the ECU controls the throttle behavior, fuel injection, and ignition timing, all changes can be made directly inside the ECU without adding additional equipment to the bike.