Methods and system are provided for indicating whether a variable orifice valve positioned in a fuel vapor recovery line of a vehicle fuel system is degraded. In one example, a method may include actively manipulating a pressure in the fuel system during a refueling event, and indicating whether the variable orifice valve is degraded based on a loading rage of a fuel vapor storage canister with fuel vapors while the pressure is actively manipulated. In this way, it may be determined as to whether the variable orifice valve is stuck in a high-flow or a low-flow position such that mitigating action may be taken to reduce or avoid release of undesired evaporative emissions to atmosphere.

A gas flow control system is provided for at least one cylinder of an internal combustion of a motor vehicle. The gas flow control system includes a supply passage configured to supply gas to the cylinder and an exhaust gas passage configured to remove gas from the cylinder. A bypass passage is configured to connect the supply passage and exhaust gas passage, and a fluid control switch is selectively operable to supply gas out of the exhaust gas passage through the bypass passage into the supply passage in an exhaust gas return operating mode, and to supply gas out of the supply passage through the bypass passage into the exhaust gas passage in a post-air operating mode.

Methods and system are provided for indicating whether a variable orifice valve positioned in a fuel vapor recovery line of a vehicle fuel system is degraded. In one example, a method may include actively manipulating a pressure in the fuel system during a refueling event, and indicating whether the variable orifice valve is degraded based on a loading rage of a fuel vapor storage canister with fuel vapors while the pressure is actively manipulated. In this way, it may be determined as to whether the variable orifice valve is stuck in a high-flow or a low-flow position such that mitigating action may be taken to reduce or avoid release of undesired evaporative emissions to atmosphere.

A gas flow control system is provided for at least one cylinder of an internal combustion of a motor vehicle. The gas flow control system includes a supply passage configured to supply gas to the cylinder and an exhaust gas passage configured to remove gas from the cylinder. A bypass passage is configured to connect the supply passage and exhaust gas passage, and a fluid control switch is selectively operable to supply gas out of the exhaust gas passage through the bypass passage into the supply passage in an exhaust gas return operating mode, and to supply gas out of the supply passage through the bypass passage into the exhaust gas passage in a post-air operating mode.

Systems and methods are described for controlling an aspirator control valve in an engine. An example method comprises closing the aspirator control valve responsive to diagnosing a first engine degradation condition and opening the aspirator control valve in response to diagnosing a second engine degradation condition.

A modulating bypass valve includes a valve housing defining a modulating fluid passageway and a bypassing fluid passageway through the valve housing. The valve also includes a throttle plate assembly that is inserted through the valve housing and has a rotating shaft on an axis that is generally perpendicular to the modulating fluid passageway and the bypassing fluid passageway. A modulating throttle plate is attached to the shaft and located within the modulating fluid passageway. A bypassing throttle plate is attached to the shaft and located within the bypassing fluid passageway. An actuator rotates the shaft.