After an engine is started, pump monitoring is performed as follows: a canister is opened to the atmosphere; a negative pressure pump is activated; and abnormality of the negative pressure pump is evaluated on the basis of canister pressure Pc detected with a pressure sensor in an evaporative leakage check module, and after the pump monitoring is completed, a switching valve is closed so that the negative pressure pump communicates with the canister for purge any fuel evaporative gas into an intake passage of the engine, and whether or not leakage has occurred in a fuel evaporative gas emission suppressor is evaluated based on the canister pressure Pc.

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 for controlling vacuum within a brake booster by modifying powertrain operation include determining an intake manifold vacuum in response to actuation of a brake pedal. Increasing the intake manifold vacuum if the brake booster vacuum is less than a desired brake booster vacuum. In some embodiments, the transmission is downshifted to increase engine speed and intake manifold vacuum.

Methods and systems are provided for controlling air flow through at least two aspirators coupled across an intake throttle. In one example, a method includes, during a first condition, opening a common aspirator shut-off valve to direct intake air through a first aspirator and a second aspirator each coupled across an intake throttle, and supplying vacuum generated by the first aspirator and the second aspirator to respective vacuum consumption devices as demanded. The method also includes, responsive to a second condition, closing the common aspirator shut-off valve and supplying intake manifold vacuum to the respective vacuum consumption devices as demanded.

Methods and systems are provided for controlling an aspirator shut-off valve in an engine of a hybrid vehicle. One example method includes opening the aspirator shut-off valve following a shut-down command to the engine when engine speed is between a first engine speed and a second engine speed, the first engine speed being lower than an idle speed and the second engine speed occurring before an imminent engine stop. The example method further includes not opening the aspirator shut-off valve between the first engine speed and the second engine speed if an oxygen content of an emission control device is at or near a threshold.

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 evaporative emissions control system for an internal combustion engine having an air intake manifold is provided. The system includes a carbon canister configured to receive fuel vapor, a purge valve fluidly coupled to the carbon canister, an air induction system configured to fluidly couple to the air intake manifold, a conduit fluidly coupled between the purge valve and the air induction system, and an inlet valve disposed in the air induction system. The inlet valve is configured to selectively move between an open position and a closed position to vary an air restriction in the air induction system and generate a vacuum. The vacuum draws fuel vapor from the carbon canister through the conduit into the air induction system.

An abnormality detection device of an internal combustion engine includes an ECU that is an abnormality detection unit detecting a leakage occurrence of a second pure pipe. When the internal combustion engine is in a supercharging operation state that a supercharger operates and the second purge pipe is closed by a second purge valve, the ECU detects the leakage occurrence of the second purge pipe based on a differential pressure between a pressure in the second purge pipe and an atmospheric pressure. In this case, the valve pressure in the second purge pipe is a pressure in the second purge pipe between the second purge valve and the intake pipe.

Methods and systems are provided for controlling an aspirator shut-off valve in an engine of a hybrid vehicle. One example method includes opening the aspirator shut-off valve following a shut-down command to the engine when engine speed is between a first engine speed and a second engine speed, the first engine speed being lower than an idle speed and the second engine speed occurring before an imminent engine stop. The example method further includes not opening the aspirator shut-off valve between the first engine speed and the second engine speed if an oxygen content of an emission control device is at or near a threshold.

After an engine is started, pump monitoring is performed as follows: a canister is opened to the atmosphere; a negative pressure pump is activated; and abnormality of the negative pressure pump is evaluated on the basis of canister pressure Pc detected with a pressure sensor in an evaporative leakage check module, and after the pump monitoring is completed, a switching valve is closed so that the negative pressure pump communicates with the canister for purge any fuel evaporative gas into an intake passage of the engine, and whether or not leakage has occurred in a fuel evaporative gas emission suppressor is evaluated based on the canister pressure Pc.