The invention relates to a method for operating a fuel supply pump of a vehicle, the vehicle comprising a combustion engine system and a gearbox, the method comprising the steps of: determining one or more operational values of at least one operational parameter of the combustion engine system; determining a reduction of a fuel provision rate to the combustion engine system; determining whether a gear step change of the gearbox is at hand, on the basis of the determined one or more operational values of the at least one operational parameter; and in case a gear step change of the gearbox is at hand, controlling operation of the fuel supply pump so as to maintain fuel supply pump speed.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.

The invention relates to a method for operating a fuel supply pump of a vehicle, the vehicle comprising a combustion engine system and a gearbox, the method comprising the steps of: determining one or more operational values of at least one operational parameter of the combustion engine system; determining a reduction of a fuel provision rate to the combustion engine system; determining whether a gear step change of the gearbox is at hand, on the basis of the determined one or more operational values of the at least one operational parameter; and in case a gear step change of the gearbox is at hand, controlling operation of the fuel supply pump so as to maintain fuel supply pump speed.

A controller for an internal combustion engine is configured to execute a rich air-fuel ratio control for performing fuel injection while setting a target equivalence ratio such that, at recovery from a fuel cutoff process, an air-fuel ratio of air-fuel mixture is richer than a stoichiometric air-fuel ratio. The controller is configured to execute a target equivalence ratio setting process for setting the target equivalence ratio that is maintained during execution of the rich air-fuel ratio control such that the target equivalence ratio increases as an air excess ratio that is calculated from an output value of a second air-fuel ratio sensor at start of the rich air-fuel ratio control increases.

A CPU of a control device is configured to perform a specific cylinder fuel cutoff process of causing an internal combustion engine to operate such that supply of fuel to some cylinders out of a plurality of cylinders is stopped and supply of fuel to the other cylinders is maintained and a fastening force decreasing process of decreasing a fastening force of a lockup clutch of a torque converter. The CPU is configured to start the specific cylinder fuel cutoff process in a state in which the fastening force has been decreased through the fastening force decreasing process when the specific cylinder fuel cutoff process is performed in a state in which the internal combustion engine operates with a load.

Methods and systems are provided for maintaining efficiency of a catalyst that is positioned in an exhaust system downstream of an internal combustion engine. In one example, the catalyst may be heated via supplying fuel to a cylinder that does not combust the fuel. The fuel may be oxidized at the catalyst via excess oxygen in the exhaust system.

Methods and systems for operating an engine that includes adjustable poppet valve timing and an exhaust gas recirculation valve are described. In one example, the exhaust gas recirculation valve is opened and the timing of the poppet valves is retarded so that an amount of fresh air that is pumped by the engine to an after treatment device may be reduced.

A control method is provided for controlling an internal combustion engine for a vehicle configured to engage a lockup clutch during a fuel cut, and to decrease a lockup hydraulic pressure at a fuel cut recovery to bring the lockup clutch to a slip engagement. The control method includes estimating a torque of the internal combustion engine generated by the fuel cut recovery when a fuel cut recovery condition is satisfied. The control method further includes decreasing a decrease amount of the lockup hydraulic pressure as the torque is greater.

A control device and a control method for a multi-cylinder internal combustion engine including a post-processing device are provided. The control device includes an electronic control unit executing a temperature raising process of raising the temperature of the post-processing device and a recovery-time process. The temperature raising process includes a stopping process and a rich process. In the stopping process, supply of fuel to several of cylinders is stopped. In the rich process, the air-fuel ratio of an air-fuel mixture for different ones of the cylinders other than the several cylinders is made lower than the stoichiometric air-fuel ratio. In the recovery-time process, the concentration of unburned fuel in exhaust gas discharged to the exhaust passage is made higher than an equivalent concentration, when the temperature raising process is stopped. The equivalent concentration is the concentration of unburned fuel being just enough to react with oxygen in the exhaust gas.

An electronic control unit (ECU) of an internal combustion engine, which includes an air-fuel ratio sensor arranged at a downstream side of an exhaust purification catalyst, is configured to judge if a state of the air-fuel ratio sensor is normal or abnormal based on the first characteristic of change of air-fuel ratio and, if a judgment cannot be made based on the first characteristic, the ECU is configured to judge if the state of the air-fuel ratio sensor is normal or abnormal based on a second characteristic of change of air-fuel ratio. As a result, it is possible to suppress the effects of the change of state of the exhaust purification catalyst while accurately diagnosing the abnormality of deterioration of response of a downstream side air-fuel ratio sensor.