Air-fuel ratio control system for engines

摘要

An air-fuel control system for an internal combustion engine is equipped with an exhaust system having a catalytic converter, a linear O2 sensor and a lambda O2 sensor for feedback controlling an air-fuel ratio on the basis of output representative of oxygen content from at least the linear O2 sensor. The system delivers a target air-fuel ratio of a fuel mixture. A determinant output, based on which the air-fuel ratio is feedback controlled, is shifted from output from the linear O2 sensor to output from the lambda O2 sensor before the linear O2 sensor is effectively active.