An internal combustion engine system includes an engine, an air intake system configured to provide intake air to the engine, and an exhaust system configured to receive exhaust gas from the engine. The engine system further includes a secondary air system including a pump, an exhaust gas recirculation (EGR) system, and a valve system operably associated with the secondary air system and the EGR system. The valve system is configured to operate in a secondary air mode where the pump is utilized to supply secondary air to the exhaust system, and an EGR mode where the pump is utilized to supply EGR to the air intake system.

An internal combustion engine system includes an engine, an air intake system configured to provide intake air to the engine, and an exhaust system configured to receive exhaust gas from the engine. The engine system further includes a secondary air system including a pump, an exhaust gas recirculation (EGR) system, and a valve system operably associated with the secondary air system and the EGR system. The valve system is configured to operate in a secondary air mode where the pump is utilized to supply secondary air to the exhaust system, and an EGR mode where the pump is utilized to supply EGR to the air intake system.

A controller, in shifting the state of the EGR system from the EGR operating state to the EGR non-operating state at the time of performing the deceleration of the vehicle, calculates a provisional EGR ratio that is a provisional value of the current EGR ratio, estimates the provisional EGR ratio as the actual EGR ratio when a fore-and-aft differential pressure of the EGR valve is equal to or more than a predetermined value, performs correction to make the provisional EGR ratio smaller, and estimates the corrected provisional EGR ratio as the actual EGR ratio when the fore-and-aft differential pressure of the EGR valve is less than the predetermined value.

A controller, in shifting the state of the EGR system from the EGR operating state to the EGR non-operating state at the time of performing the deceleration of the vehicle, calculates a provisional EGR ratio that is a provisional value of the current EGR ratio, estimates the provisional EGR ratio as the actual EGR ratio when a fore-and-aft differential pressure of the EGR valve is equal to or more than a predetermined value, performs correction to make the provisional EGR ratio smaller, and estimates the corrected provisional EGR ratio as the actual EGR ratio when the fore-and-aft differential pressure of the EGR valve is less than the predetermined value.

An internal combustion engine system includes an engine, an air intake system configured to provide intake air to the engine, and an exhaust system configured to receive exhaust gas from the engine. The engine system further includes a secondary air system including a pump, an exhaust gas recirculation (EGR) system, and a valve system operably associated with the secondary air system and the EGR system. The valve system is configured to operate in a secondary air mode where the pump is utilized to supply secondary air to the exhaust system, and an EGR mode where the pump is utilized to supply EGR to the air intake system.

An internal combustion engine system includes an engine, an air intake system configured to provide intake air to the engine, and an exhaust system configured to receive exhaust gas from the engine. The engine system further includes a secondary air system including a pump, an exhaust gas recirculation (EGR) system, and a valve system operably associated with the secondary air system and the EGR system. The valve system is configured to operate in a secondary air mode where the pump is utilized to supply secondary air to the exhaust system, and an EGR mode where the pump is utilized to supply EGR to the air intake system.

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.

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 boosted engine is provided, which includes a first turbocharger having a first compressor and a first turbine, a second turbocharger having a second compressor and a second turbine, and first and second exhaust emission control devices. The engine has a first exhaust port which opens at a first timing, and a second exhaust port which is in parallel with the first exhaust port and opens at a second timing later than the first timing. The exhaust passage has a first exhaust passage connected to the first exhaust port and a second exhaust passage connected to the second exhaust port. The first turbine and the first exhaust emission control device are disposed in the first exhaust passage in this order from upstream to downstream, and the second exhaust emission control device and the second turbine are disposed in the second exhaust passage in this order from upstream to downstream.

A boosted engine is provided, which includes a first turbocharger having a first compressor and a first turbine, a second turbocharger having a second compressor and a second turbine, and first and second exhaust emission control devices. The engine has a first exhaust port which opens at a first timing, and a second exhaust port which is in parallel with the first exhaust port and opens at a second timing later than the first timing. The exhaust passage has a first exhaust passage connected to the first exhaust port and a second exhaust passage connected to the second exhaust port. The first turbine and the first exhaust emission control device are disposed in the first exhaust passage in this order from upstream to downstream, and the second exhaust emission control device and the second turbine are disposed in the second exhaust passage in this order from upstream to downstream.