Methods and systems, using a controller (20), for performing fuel pressure control operation of an engine (12) having at least one cylinder (16) is disclosed. The controller (20) includes a fuel system control unit (42) configured to control a fuel pressure applied to at least one injector (18) of the engine (12) during a motoring condition period (412) based on a commanded pulse train duration (410). During the motoring condition period (412), no combustion occurs in the at least one cylinder (16) of the engine (12). The commanded pulse train duration is a time period during which the at least one injector (18) of the engine (12) is activated for a drain operation. The fuel system control unit (42) is configured to command the at least one injector (18), for the commanded pulse train duration during the motoring condition period (412), to release fuel from the at least one injector (18) without injecting the fuel into the at least one cylinder (16) of the engine (12).

A method for identifying a continuously injecting combustion chamber of an internal combustion engine which has an injection system with a high-pressure accumulator for a fuel, having the following steps: time-dependent sensing of a high pressure in the injection system; starting a continuous-injection detection process at a starting time while the internal combustion engine is operating; identifying a start time of a pressure drop which occurs chronologically before the starting time and at which the high pressure in the injection system begins to drop if continuous injection has been detected; and identifying at least one combustion chamber to which the continuous injection can be assigned, on the basis of the start time of the pressure drop.

A method of operating a fuel injection system for a motor vehicle includes one or more of the following: operating a fuel injector to perform a fuel injection, the fuel injector being in fluid communication with a fuel rail; sampling a rail pressure in the fuel rail during the fuel injection; regulating the rail pressure at a desired injection pressure, P.sub.inj, to the fuel injector; measuring an overall leakage on variations of the rail pressure across an engine cycle for the motor vehicle and between two engine positions of an internal combustion engine for the motor vehicle; and restarting a new measurement cycle for a new pressure measurement target.

A method for operating an internal combustion engine having a high-pressure fuel injection system stops and starts the engine independently of an intervention by the motor vehicle operator and then restarted. A high-pressure fuel pump is used to pump fuel to a high-pressure reservoir to which at least one high-pressure fuel injector is connected in order to inject fuel into the at least one cylinder of the internal combustion engine. Fuel pressure can be adjusted on the high-pressure side using an electrically actuated pressure reduction valve (PDV).

A method of increasing parasitic load on an internal combustion engine includes injecting a fuel into a combustion chamber of an active cylinder of the internal combustion engine, combusting the injected fuel in the combustion chamber of the active cylinder, and determining that increasing a temperature of an exhaust aftertreatment device is required. The method includes increasing a parasitic load on the internal combustion engine by deactivating a cylinder, wherein no fuel is injected in the deactivated cylinder for a combustion cycle of the internal combustion engine, and further increasing the parasitic load by pulsing a spill valve member of a spill valve of a fuel injector in the deactivated cylinder between a fully closed position and an at least partially open position.

A method for operating an internal combustion engine having a number of cylinders and an injection system having an injection system that has a common rail and a number of injectors associated with the cylinders, wherein an individual accumulator is associated with each injector and stores fuel from the common rail for the injector. The method has the following steps: starting the internal combustion engine, operating the internal combustion engine, shutting off the internal combustion engine. The following steps are also provided: a state indicating an engine standstill is detected, in particular after the internal combustion engine has been shut off, a high-pressure limit value is defined and a target high pressure is specified, a leakage is produced in the common rail without injection, the fuel pressure in the common rail is reduced to the defined high-pressure limit value below the target high pressure by way of the leakage.

A method for identifying a continuously injecting combustion chamber of an internal combustion engine which has an injection system with a high-pressure accumulator for a fuel, having the following steps: time-dependent sensing of a high pressure in the injection system; starting a continuous-injection detection process at a starting time while the internal combustion engine is operating; identifying a start time of a pressure drop which occurs chronologically before the starting time and at which the high pressure in the injection system begins to drop if continuous injection has been detected; and identifying at least one combustion chamber to which the continuous injection can be assigned, on the basis of the start time of the pressure drop.

A fuel injector for a combustion engine is disclosed. The fuel injector includes an injector body having a nozzle orifice, a solenoid coil mounted in the injector body, a control chamber filled with high-pressure fuel, an armature moved by electromagnetic force of the solenoid coil to vary fuel pressure in the control chamber, and a needle that moves to open or close the nozzle orifice according to the variation in the fuel pressure in the control chamber. The fuel injector further includes piezoelectric actuator for adjusting a fuel injection rate by adjusting an opening speed of the nozzle orifice based on a load condition of the engine.

An estimation device applicable to a combustion system having an internal combustion engine includes a mixing acquisition unit, a combustion amount estimation unit, a region estimation unit, and a timing estimation unit. The mixing acquisition unit acquires a mixing ratio of various components contained in fuel used for combustion in the internal combustion engine. The combustion amount estimation unit estimates a combustion amount of fuel caused by a post combustion generated by injecting fuel into a combustion chamber of the internal combustion engine by post injection, based on the mixing ratio acquired by the mixing acquisition unit. The region estimation unit estimates a combustion region of the post combustion in the combustion chamber based on the mixing ratio. The timing estimation unit estimates an ignition timing at which ignition occurs in the combustion chamber by the post injection based on the mixing ratio.

Methods and systems are provided for adjusting operation of fuel injectors of an internal combustion engine to reduce injector ticking noise during direct injection fuel rail pressure release. The method includes first reducing a significant part of the direct injection fuel rail pressure via a mechanical high pressure pump relief valve and only if further pressure relief is required then intermittently activating the direct injector to inject in small amount of fuel. Due to the reduced frequency of activation and small pulse-widths, the impact force transmitted from injectors to cylinder head is small thereby reducing the objectionable ticking noise.