EGR Cooler Bypass Valve Diagnostic Strategy

摘要

In proposed diagnostic strategy, EGR cooler efficiency is monitored in strong exhaust warm up combustion mode (V3 mode) after certain enablement conditions are met. In V3 mode, the bypass valve is opened and EGR flows through the bypass. If the EGR cooler efficiency is below the calibratable threshold, then the bypass valve Is functioning normally and the diagnostic is passed otherwise it fails. The proposed diagnostic method is a passive strategy. It eliminates use of intrusive tests and the need for a bypass valve position sensor.