A method of controlling vacuum pressure for vehicle braking may include checking whether a vehicle is idle or enters a deceleration state, comparing an engine vacuum pressure and a booster vacuum pressure of the vehicle with a preset reference value, checking whether a valve control system of the vehicle is operable when the engine vacuum pressure and the booster vacuum pressure are lower less than the preset reference value, controlling the valve control system when the valve control system is operable; and controlling an air conditioner (A/C) or an alternator of the vehicle when the valve control system is inoperable.

A system includes a three-way catalyst (TWC) sulfur load module, a cylinder/fuel cutoff module, a fuel control module, and a valve control module. The TWC sulfur load module is configured to determine an amount of sulfur deposited on a three-way catalyst of an engine in a vehicle. The cylinder/fuel cutoff module is configured to determine whether to enable deceleration cylinder cutoff (DCCO) based on the amount of sulfur deposited on the three-way catalyst. The fuel control module is configured to control a fuel injector to selectively stop fuel injection in the engine when DCCO is enabled. The valve control module is configured to selectively maintain intake and exhaust valves of the engine in a closed position when DCCO is enabled.

Methods and systems for maintaining a temperature of catalyst above a threshold temperature during vehicle braking and coasting is described. In one example, engine pumping work may be increased without increasing flow of cool fresh air through the engine's exhaust system to provide a desired level of engine braking. The net air flow through the engine may be reduced via activating a decompression actuator.

A controller for a hybrid vehicle controls a first motor generator and a second motor generator such that electric power input to a battery does not exceed an input upper limit value and electric power output from the battery does not exceed an output upper limit value. The controller executes motoring to rotate an output shaft using the first motor generator with combustion operation of an engine stopped, thereby causing a braking force generated by friction of the engine to act on a driven wheel. The controller executes a valve-opening limitation process that limits an increase in a throttle open degree in correspondence with the input upper limit value upon issuance of an increase request for the throttle open degree that is not based on an operation of requesting a change in the braking force performed by a driver during the execution of the motoring.

A method for operating an internal combustion engine having a cylinder, an intake valve, an air pipe, and a valve element disposed in the air pipe, includes detecting a signal for causing a fuel supply of the cylinder to switch off. The valve element is moved out of a first position into a second position triggering a lower flow cross-section while the fuel supply is still activated, where a first cam for actuating the intake valve is allocated to the intake valve. While the fuel supply is still activated, switching from the first cam to a second cam and via the second cam the intake valve is actuated such that the intake valve causes a reduced air intake. An exhaust cam shaft for actuating an exhaust valve is set in an advance direction such that a valve intersection of the intake valve and of the exhaust valve ceases.

A method for controlling an electrical exhaust gas turbocharger of an internal combustion engine includes a measure (a), in accordance with which a load requirement placed on the internal combustion engine is monitored, and a measure (b), in accordance with which a boost mode of the electrical exhaust gas turbocharger is activated if the load requirement monitored in measure (a) exceeds a predetermined threshold value.

Various methods and arrangements for improving fuel economy and noise, vibration, and harshness (NVH) in a skip fire controlled engine are described. An engine controller dynamically selects a gas spring type for a skipped firing opportunity. Determination of the skip/fire pattern and gas spring type may be made on a firing opportunity by firing opportunity basis.

An engine system is provided with an electronic throttle device to regulate intake amount to the engine, an EGR device (EGR valve) to recirculate a part of exhaust gas of the engine to the engine as EGR gas, and an electronic control unit (ECU) to control the electronic throttle device and the EGR valve based on an operating state of the engine. The ECU performs feedback control of the electronic throttle device such that a detected engine rotation number becomes a target idle rotation number, and sets the target idle rotation number to a predetermined first set value for avoiding engine stall until a predetermined time elapses from start of deceleration and then shifts the target idle rotation number to a second set value lower than the first set value after the predetermined time elapses.

An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders, an air intake system to provide air to the plurality of cylinders through respective ones of a plurality of intake valves, an exhaust system to release exhaust gas from the plurality of cylinders through respective one of a plurality of exhaust valves. The internal combustion engine uses vacuum braking and/or compression release braking in response to one or more braking conditions.

Controllers and methods for managing transitions into and/or out of a cylinder cut off mode are described. In some embodiments, a skip fire based transition into a cylinder cut off mode is used in which the fraction of working cycles that are fired is gradually reduced to a threshold firing fraction. Once the threshold firing fraction has been reached, all of the working chambers are deactivated.