The OBD Smart System is a sequential gas injection system. When operational, the gas ECU utilizes the fuel injection signal from the vehicle’s original system as its primary input. Simultaneously, it gathers parameters such as engine coolant temperature and gas pressure to determine the optimal gas injection timing. The gas rail injectors then supply gas to the corresponding engine cylinders. Within the allowable engine cylinder volume range, the system ensures that the gas supplied matches the energy output of gasoline. When the switch is set to gas mode, the gas ECU automatically detects the preset conversion conditions stored within it. Upon meeting these conditions, the system switches to gas operation. During this phase, the gasoline injection nozzles are deactivated, and the gas system ECU initiates the gas rail injectors to begin supplying gas.