An Evaluation of Techniques for Measuring Air-Fuel Ratio

Four methods for determining air-fuel ratio by exhaust analysis are compared. The methods selected for study are all potentially useful with analyses of integrated samples obtained in road tests or exhaust samples generated in the laboratory. A V-8 engine mounted on an engine dynamometer was used to generate exhaust, from which the air-fuel ratios were determined simultaneously by the various methods. The air-fuel ratio of the mixture delivered to the engine was determined by measuring directly the quantities of air and fuel supplied. This value was compared to those obtained by the four exhaust analysis techniques. Comparisons were made during normal operation and during conditions of deliberate cylinder misfire to simulate the most adverse combustion condition encountered on the road. One of the methods has distinct advantages which are discussed.