| 摘要 |
A system and method for diagnosing a component failure in an internal combustion engine having an exhaust gas recirculation system and a variable geometry turbocharger for diverting exhaust gas from an engine exhaust to an engine intake include determining whether the engine is operating in boost control mode or EGR control mode, comparing EGR flow rate to a threshold corresponding to the current control mode, generating a fault if the EGR flow rate is outside an acceptable operating range based on the threshold for a first predetermined time period, and operating in boost control mode if the fault persists for a second predetermined time period. In one embodiment, the system and method determine that the engine is operating in the EGR control mode with the threshold corresponding to a minimum EGR flow rate and determine whether the EGR flow rate exceeds the threshold. The system and method then determine whether the EGR flow rate is within an acceptable operating range relative to a desired EGR flow rate and generate a VGT fault if the EGR flow rate is outside of the acceptable operating range but exceeds the minimum threshold. Likewise, the system and method generate an EGR fault if the EGR flow rate is less than the minimum threshold. When operating in the boost control mode, the system and method generate an EGR fault if the EGR mass flow rate exceeds a maximum flow rate and generate a VGT fault if the turbo boost pressure is not within an acceptable operating range of a desired boost pressure. |
