Diagnostic system for catalytic converter damage in combustion engine

摘要

A three-way catalytic converter (27) for CO and hydrocarbon oxidn. and NOx redn. is located in the exhaust pipe (23) between upstream and downstream residual O2 sensors (28,29). These are wired to a monitoring unit (32) in common with sensors of intake air flow (26), coolant temp. (30) and crankshaft angular position (31). Catalyst poisoning is ascertained from comparison of the inversion state of outputs from the oximeter with a decision standard. Air/fuel ratio feedback coeffts. are calculated and used to correct the basic quantity of fuel injected (24).