Systems are provided for detecting a change in performance of an engine component. In one example, a system includes a first pressure sensor of a first exhaust manifold coupled to a first subset of cylinders of an engine, a second pressure sensor of a second exhaust manifold coupled to a second subset of cylinders of the engine, a passage coupling the first exhaust manifold to an intake manifold, and a controller configured to detect a change in performance of any cylinder of the engine based on frequency content from the first pressure sensor and from the second pressure sensor during both a first mode where no exhaust gas from the first exhaust manifold is provided to the intake manifold, and during a second mode where all exhaust gas from the first exhaust manifold is provided to the intake manifold, and adjust an operating parameter responsive to the change in performance.

A method of operating exhaust gas recirculation pump for an internal combustion engine including: providing an EGR pump assembly including an electric motor coupled to a roots device having rotors, the EGR pump operably connected to an internal combustion engine; providing an system controller; providing an EGR control unit linked to the EGR pump assembly; sending a speed command from the system controller to the EGR control unit; determining if a motor temperature and module temperature is within a predetermined target; outputting a desired speed signal; determining if a motor speed is within a predetermined target; determining if a motor voltage is within a predetermined target; and outputting a current to the electric motor controlling the speed of the electric motor and regulating an EGR mass flow rate.

A method of operating exhaust gas recirculation pump for an internal combustion engine including: providing an EGR pump assembly including an electric motor coupled to a roots device having rotors, the EGR pump operably connected to an internal combustion engine; providing an system controller; providing an EGR control unit linked to the EGR pump assembly; sending a speed command from the system controller to the EGR control unit; determining if a motor temperature and module temperature is within a predetermined target; outputting a desired speed signal; determining if a motor speed is within a predetermined target; determining if a motor voltage is within a predetermined target; and outputting a current to the electric motor controlling the speed of the electric motor and regulating an EGR mass flow rate.

Embodiments for diagnosing a humidity sensor are provided. One example method comprises, responsive to a humidity sensor test cycle, pumping air conditioning and windshield washer gas flows past a humidity sensor, and indicating humidity sensor degradation based on a response of the humidity sensor to the air conditioning and windshield washer gas flows. In this way, degradation of the humidity sensor may be indicated if the humidity sensed by the humidity sensor does not change responsive to the humidity sensor test cycle being initiated.

Embodiments for diagnosing a humidity sensor are provided. One example method comprises, responsive to a humidity sensor test cycle, pumping air conditioning and windshield washer gas flows past a humidity sensor, and indicating humidity sensor degradation based on a response of the humidity sensor to the air conditioning and windshield washer gas flows. In this way, degradation of the humidity sensor may be indicated if the humidity sensed by the humidity sensor does not change responsive to the humidity sensor test cycle being initiated.

Methods and systems are provided for determining degradation of an EGR cooler based on differential pressure across the EGR cooler during EGR flow. In one example, the differential pressure across the EGR cooler may be based on differential pressure across an EGR valve and a pressure downstream from the EGR valve with and without EGR flow. The pressure downstream from the EGR valve may be a compressor inlet pressure or an intake manifold pressure in a low pressure EGR system or high pressure EGR system, respectively.

Methods and systems are provided for determining degradation of an EGR cooler based on differential pressure across the EGR cooler during EGR flow. In one example, the differential pressure across the EGR cooler may be based on differential pressure across an EGR valve and a pressure downstream from the EGR valve with and without EGR flow. The pressure downstream from the EGR valve may be a compressor inlet pressure or an intake manifold pressure in a low pressure EGR system or high pressure EGR system, respectively.

An anomaly determination unit includes an EGR amount acquisition section configured to acquire an actual amount of an EGR amount, which is a flow rate of EGR gas; an estimation amount computation section configured to compute an estimated amount of the EGR amount based on a working gas pressure, which is a pressure of working gas in which the EGR gas and intake air are mixed, an EGR temperature, which is a temperature of the EGR gas immediately upstream of an EGR valve, an EGR pressure, which is a pressure of the EGR gas immediately upstream of the EGR valve, and an opening degree instruction value for the EGR valve; and a determination section configured to determine the presence or absence of an anomaly in the EGR valve based on the divergence between the actual amount of the EGR amount and the estimated amount.

An anomaly determination unit includes an EGR amount acquisition section configured to acquire an actual amount of an EGR amount, which is a flow rate of EGR gas; an estimation amount computation section configured to compute an estimated amount of the EGR amount based on a working gas pressure, which is a pressure of working gas in which the EGR gas and intake air are mixed, an EGR temperature, which is a temperature of the EGR gas immediately upstream of an EGR valve, an EGR pressure, which is a pressure of the EGR gas immediately upstream of the EGR valve, and an opening degree instruction value for the EGR valve; and a determination section configured to determine the presence or absence of an anomaly in the EGR valve based on the divergence between the actual amount of the EGR amount and the estimated amount.

A system and method for controlling an exhaust gas recirculation (EGR) system in a hybrid vehicle using an intrusive monitor include adjusting EGR flow through an EGR valve based on an average pressure difference between pressure measured from a manifold absolute pressure (MAP) sensor and inferred pressure determined from mass air flow (MAF) into an intake of an engine when engine speed, throttle and camshaft timing position change is below a corresponding threshold. The measured pressure and inferred pressure are determined when the EGR valve is in a closed position and an open position.