OBD 1 Smart System is a gas sequential injection gas supply system. When the system works, the gas  ECU takes the fuel injection signal from original vehicle as the basic signal, and collects the parameters of the engine colling water temperature, gas pressure and other parts at the same time to decide the final gas injection time and gas rall injectior supply gas to the corresponding engine cylinder. Within the permitted scope of engine cylinder volum, the system will provide gas which is equal to the energy of the gasoline when the switch is in the gas position, the gas ECU will automatically defect the conversion conditions which are already stored in the ECU. When the condition is met, system will switch to the gas. At this time, the gasolIne injection nozzle is cut off, and the gas system ECU drives the gas rail injector to start working.