External exhaust gas recirculation on board diagnostic using EGR effect on a combination of engine operating parameters

摘要

A system is described for determining degradation of an exhaust gas recirculation system of an internal combustion engine. This method utilizes a combination of parameters to accurately determine degradation of the exhaust gas recirculation system. For example, the system utilizes changes in intake manifold pressure, changes in idle speed control operation, changes in ignition timing, and fueling changes to accurately determine operation of the exhaust gas recirculation system.