Simple method of measuring nitrogen oxide in running vehicles

The present invention relates to a simple method of measuring the weight of nitrogen oxide emitted from an engine of a vehicle such as a motorcar running on an actual road surface. The present invention provides a simple method of measuring NOin a running vehicle. While running on an actual road surface, the weight of NOemitted from an engine of the running vehicle can be found more simply and accurately. The present invention comprises mounting a NOanalyzer, an air-fuel ratio sensor, and a data collection device on a vehicle, allowing the vehicle to run on the actual road surface, introducing the exhaust gas emitted while running on the actual road surface to a NOanalyzer to determine the concentration of NOcontained in the exhaust gas, determining a flow rate of the exhaust gas by using a fuel injection quantity based on a fuel injection pulse output from an electronic control unit mounted on the vehicle and an output from the air-fuel ratio sensor, and determining the weight of NOemitted from the engine from the flow rate of the exhaust gas and the concentration of NO.