Diagnostics for Emission Control System Malfunction on Three-Way Catalyst-Equipped Vehicles

摘要

The report presents the results of a two part study. In Phase I, the contractor reviewed current manufacturer recommended diagnostic procedures for identifying vehicular emission control malfunctions on three-way catalyst equipped gasoline fueled automobiles and also surveyed diagnostic techniques used in the field. Diagnosis of malperformance was limited to the following systems: exhaust gas recirculating, secondary air, fuel, and catalyst. In Phase II, the contractor developed generalized diagnostic procedures for malfunctioning emission control systems and validated these procedures on 52 vehicles. Two mechanics alternatively disabled and repaired the vehicles using the diagnostic and repair procedures. The report also describes inspection procedures developed for the control of smoke emissions from light-duty diesel vehicles. Two types of procedures were developed, for component testing and for inspection/maintenance programs. These procedures were validated on six light-duty vehicles.