Methods and systems are provided for improving the efficiency of canister purge completion. Based on engine operating conditions, a canister is purged to a compressor inlet or a throttle outlet. During purging conditions, as canister loads change, a purge flow through the canister is varied so that a fixed preselected portion of total engine fueling is delivered as fuel vapors.

Methods and arrangements for transitioning an engine between a deceleration cylinder cutoff (DCCO) state and an operational state are described. In one aspect, transitions from DCCO begin with reactivating cylinders to pump air to reduce the pressure in the intake manifold prior to firing any cylinders. In another aspect, transitions from DCCO, involve the use of an air pumping skip fire operational mode. After the manifold pressure has been reduced, the engine may transition to either a cylinder deactivation skip fire operational mode or other appropriate operational mode. In yet another aspect a method of transitioning into DCCO using a skip fire approach is described. In this aspect, the fraction of the working cycles that are fired is gradually reduced to a threshold firing fraction. All of the working chambers are then deactivated after reaching the threshold firing fraction.

Methods and systems are provided for a vacuum generating device. In one example, a vacuum generating device comprises a venturi device upstream of an annular fixture for adjusting an amount of vacuum provided to a vacuum consumption device.

Methods and arrangements for transitioning an engine between a deceleration cylinder cutoff (DCCO) state and an operational state are described. In one aspect, transitions from DCCO begin with reactivating cylinders to pump air to reduce the pressure in the intake manifold prior to firing any cylinders. In another aspect, transitions from DCCO, involve the use of an air pumping skip fire operational mode. After the manifold pressure has been reduced, the engine may transition to either a cylinder deactivation skip fire operational mode or other appropriate operational mode. In yet another aspect a method of transitioning into DCCO using a skip fire approach is described. In this aspect, the fraction of the working cycles that are fired is gradually reduced to a threshold firing fraction. All of the working chambers are then deactivated after reaching the threshold firing fraction.

An EGR valve is provided in an EGR passage circulating a part of an exhaust gas of an exhaust pipe in an intake pipe as an EGR gas, the EGR valve adjusting an EGR gas amount flowing in the EGR passage when an engine is in an EGR region, a differential pressure device is provided in the intake pipe, the differential pressure device adjusting a differential pressure of the EGR valve, a control unit is provided to control the EGR valve and the differential pressure device, and the EGR control method includes switching whether to adjust the EGR gas amount using the EGR valve and the differential pressure device or to adjust the EGR gas amount using the EGR valve only on the basis of an exhaust gas pressure of an inlet portion of the EGR passage.

A throttle device is provided at the intake passage downstream of a compressor, a purge passage is connected to the intake passage upstream from the compressor, a purge valve is provided in the purge passage, an inlet valve is provided upstream of a connection position between the purge passage and the intake passage, and an air flow meter is provided in the intake passage upstream of the inlet valve. An electronic control device: calculates a target purge flow rate (TPFR) for vapor to the intake passage while the throttle device is controlled to a prescribed opening degree and the inlet valve is controlled to a target intake opening degree (TIOP); calculates the target purge opening degree to ensure the TPFR; controls the purge valve to the TIOP and corrects the TIOP by the TPFR; and controls the inlet valve by the corrected TIOP.

Methods and systems for providing vacuum to a vehicle are described. In one example, a method adjusts an engine air-fuel ratio in response to provide additional vacuum to the vehicle.

A method for controlling an engine variable valve timing of a hybrid electric vehicle, may include providing a cam position setting table of a fuel efficiency prioritized intake/exhaust cam control mode, and a cam position setting table of a normal intake/exhaust cam control mode, the cam position setting table of the fuel efficiency prioritized intake/exhaust cam control mode being differentiated from the cam position setting table of the normal intake/exhaust cam control mode; selecting one of the fuel efficiency prioritized intake/exhaust cam control mode and the normal intake/exhaust cam control mode by a canister loading amount and whether or not diagnosis of an intake cam and diagnosis of an exhaust cam are completed; and determining position control values of the intake and exhaust cams by using the cam position setting table and then controlling positions of the intake cam and the exhaust cam by the determined position control values.

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.

An EGR valve is provided in an EGR passage circulating a part of an exhaust gas of an exhaust pipe in an intake pipe as an EGR gas, the EGR valve adjusting an EGR gas amount flowing in the EGR passage when an engine is in an EGR region, a differential pressure device is provided in the intake pipe, the differential pressure device adjusting a differential pressure of the EGR valve, a control unit is provided to control the EGR valve and the differential pressure device, and the EGR control method includes switching whether to adjust the EGR gas amount using the EGR valve and the differential pressure device or to adjust the EGR gas amount using the EGR valve only on the basis of an exhaust gas pressure of an inlet portion of the EGR passage.