ENGINE AIR TO FUEL RATIO CYLINDER IMBALANCE DIAGNOSTIC

摘要

A diagnostic for identifying cylinder to cylinder air/fuel ratio faults of an engine having closed loop fuel control. Air mass flow is accumulated for a plurality of load bands on the engine load/speed map, and for each load band a rich/lean air fuel ratio is determined at a mass threshold. This threshold data is processed and compared with fixed data to determine whether any cylinder of an engine is experiencing an air/fuel ratio fault which is substantially different to the remainder.