Methods and systems are provided for conducting vehicle fuel system and/or evaporative emissions system diagnostics, where the diagnostics rely on a positive pressure with respect to atmospheric pressure. In one example, a method comprises activating an electric compressor positioned in an intake of an engine configured to receive purge gasses from the evaporative emissions system under boosted engine operation and natural engine operation, to direct a positive pressure with respect to atmospheric pressure to the fuel system and/or evaporative emission system to conduct said diagnostic. In this way, diagnostics that rely on positive pressure with respect to atmospheric pressure may be conducted in vehicles with a dual-path purge system, without introduction of a pump in the evaporative emissions system.

An intake control method for an internal combustion engine equipped with a low-pressure EGR system includes setting a target intake pressure, which is a target value of an intake pressure in an intake passage between a negative pressure generating valve and an intake throttle valve, necessary for performing EGR control in a state of an exhaust pressure determined for each operating point, setting a target total opening area, which is a sum of a target opening area of an EGR valve and a target opening area of the negative pressure generating valve, on the basis of the target intake pressure, a target fresh air amount, and a target EGR gas amount, setting a target EGR valve opening area, which is an opening area of the EGR valve for achieving the target EGR gas amount, assuming that the negative pressure generating valve is fully open, and setting a value obtained by subtracting the target EGR valve opening area from the target total opening area to be a target negative pressure generating valve opening area, which is a target value of an opening area of the negative pressure generating valve.

Methods and systems are provided for taking mitigating action where a canister purge valve configured to control an amount of fuel vapors inducted into the engine during purging operations of a fuel vapor storage canister, is indicated as being degraded. In one example, a method comprises controlling an amount of pressure directed to a fuel tank and the fuel vapor storage canister via a pump positioned downstream of the fuel tank and canister to actively route fuel vapors to the canister during a refueling event. In this way, fuel vapors may be prevented from being routed to engine intake under conditions of a degraded canister purge valve, which may reduce opportunity for vehicle stall, improve driveability, and which may reduce release of undesired evaporative emissions to atmosphere.

An internal combustion engine is provided with: an electric supercharger including an electric compressor; an EGR introduction port formed upstream of the electric compressor; a throttle valve A arranged upstream of the EGR introduction port; and a control device. A throttle valve B other than the throttle valve A is not arranged in the intake air passage. The control device is configured, in a non-supercharging region, to execute a first air flow rate adjustment processing that adjusts an intake air flow rate by adjusting the opening degree of the throttle valve A while driving the electric supercharger to cause a pressure ratio of the electric compressor to approach 1; and a second air flow rate adjustment processing that adjusts the intake air flow rate by adjusting the opening degree of the throttle valve A while not energizing the electric supercharger.

Systems and methods for detecting a clogged intake air filter in a turbocharged engine system are provided. In one example a method for an engine coupled to an air filter and to a fuel tank includes indicating air filter clogging responsive to a measured fuel tank pressure during boosted engine operation. In this way, clogging of the air filter may be determined using existing engine system components.

Systems and methods for increasing engine vacuum production and catalyst heating of a hybrid powertrain are described. In one example, a motor/generator rotates an engine at idle speed while the engine combusts air and fuel without providing torque sufficient to rotate the engine so that spark timing may be advanced or retarded from minimum spark timing for best torque to heat a catalyst and generate vacuum for vacuum consumers.

A negative pressure control valve (44) is disposed in a part of an intake passage (12) upstream of a confluence (30) of an EGR passage (27) and the intake passage (12). When in an EGR region (Regr) where an EGR gas is recirculated to the intake passage (12) through the EGR passage (27), the negative pressure control valve (44) is controlled in a manner to ensure a differential pressure between an exhaust passage (13) and the intake passage (12). When in an operation region (R2) lower in load than the EGR region (Regr), the negative pressure control valve (44) is controlled in a closing direction so as to suppress occurrence of noise.

Methods and systems are provided for generating vacuum via a throttle. In one example, a method may comprise rotating the throttle to a first fully closed position to provide vacuum to a first vacuum consumption device and rotating the throttle to a second fully closed position to provide vacuum to a second vacuum consumption device. The method may further include rotating the throttle to a partially closed position to provide vacuum to both the first and second vacuum consumption devices.

A vehicle having a valve stop mode control unit configured such that an intake valve and an exhaust valve are stopped in a closed state during rotation of an output shaft, supply of fuel to an engine is stopped, a clutch is made to be in an engaged state, and pistons are driven by rotational forces from driving wheels through the output shaft. When there is a request for valve stop inertial running, a negative pressure is supplied to an intake passage by a vacuum pump.

Methods and systems are provided for expediting catalyst warm-up. In one example, a method may include flowing exhaust gas from an engine first through an emission control device and then through a turbine to rotate the turbine in a reverse direction, the rotation of the turbine in the reverse direction generating intake manifold vacuum for a vacuum consumer via a compressor coupled to the turbine. In this way, heat loss through a turbine may be avoided.