A Portable Fast Response Air-Fuel Ratio Meter Using an Extended Range Oxygen Sensor

The method for measuring air-fuel ratio is generally based on analysis of the exhaust gas components and its calculations. A new instrument has been developed which uses this method, but it attaches an oxygen sensor for exhaust gas analysis to the exhaust pipe and calculates the air-fuel ratio directly from the sensor output using a microprocessor.

The response time of this instrument is 100 milliseconds and because it does not require an exhaust gas sampling system its weight is only 2.5 kg.

This paper describes the operation theory, construction and characteristics of this instrument, as well as the results of air-fuel ratio of measurements on engines and vehicles using this instrument in a transient state.