Air/fuel ratio validation for lean burn

摘要

A multi-cylinder group engine system operable in at least a first mode and a second mode, where in the first mode a first and second cylinder group combust air and fuel, and where in the second mode at least one of the first and second cylinder group combusts air and fuel and the other one of the first and second cylinder group pumps air without injected fuel, the engine system comprising of a first linear exhaust gas sensor disposed in a first exhaust passage to measure air fuel exhausted from the first cylinder group; a first switching type exhaust gas sensor disposed in a second exhaust passage to measure air-fuel exhausted from the second cylinder group; a second linear exhaust gas sensor disposed downstream of a junction between the first exhaust passage and the second exhaust passage; and a controller configured to validate a reading of the first linear exhaust gas sensor during the first mode of engine operation based on a reading of the second linear exhaust gas sensor when a lean air-fuel ratio is commanded.