Double Hego method for identifying and mitigating air-fuel imbalance errors

摘要

Systems and methods for identifying and mitigating air-fuel imbalance errors specific to an engine cylinder are provided. In one embodiment, a method includes indicating cylinder imbalance by comparing time-aligned measurements from the exhaust oxygen sensors, wherein the exhaust oxygen sensors are positioned symmetrically within an exhaust passage downstream of a catalyst. In this way, an error of air-fuel imbalance in a non-uniform exhaust flow can be accurately detected, so that mitigating actions can be taken resulting in reduced exhaust tailpipe emissions.