A booster circuit installed in a fuel injection device of an internal combustion engine, wherein malfunctions and characteristic changes of the booster circuit are detected, among which the detection distinguishes between decreases in capacity caused by deterioration or broken wires in a booster capacitor, and failures of a current monitor circuit, coil, externally connected fuel injection valve, and other components. The range of decrease in boost voltage when the fuel injection valve is opened is monitored, as is the range of increase per switch performed in order to restore the boost voltage. This makes it possible to detect malfunctions and characteristic changes of the booster circuit.

In an embodiment, a pressure sensor includes a tip secured to a port. The tip includes an opening for receiving pressure to be measured by the pressure sensor. The port includes a threaded section for mounting the pressure sensor in a fixture such as, for example, a rail. The port also includes a flexible section, a cavity, and an opening. The opening in the tip receives pressure from an outside source and channels the pressure to the opening of the port. The opening of the port receives the pressure from the tip and channels the pressure to the cavity. The pressure received in the cavity applies a force to the flexible section which flexes in response to the force. Moreover, forces are provided by the tip and the threaded section to keep the tip secured to the port.

A control apparatus for operating a fuel injector is provided. The control apparatus includes an electronic control unit configured to: identify when the engine is running under a fuel cut-off condition, and then perform a learning procedure to determine an actual value of energizing time that causes the fuel injector to inject a target fuel quantity. The learning procedure provides for the electronic control unit to perform several test injections with different energizing time values and measure an engine torque value caused by the test injection. The measured engine torque values and their correspondent energizing time values are used to extrapolate the actual value of the energizing time as the value that corresponds to a reference value of engine torque that is consistent with the target fuel quantity.

In an injector driving apparatus, a driving circuit supplies a current individually to each coil of multiple injectors, a current detection element detects the current flowing in a common current flow path, which is common to the coils, a current supply period guard part forcibly stops the current supplied from the driving circuit to the coil upon determination that a measured period reached a predetermined set period based on a detection result of the current detection element, and a diagnosis part operates in a period of no fuel injection to check whether the current supply period guard part normally stops the current supplied to the coil, by continuously supplying the current to the coil for only a short period, which disables the injector to open a valve, and sequentially switches over the coils.

The disclosure describes systems and methods of detecting a misfire in a cylinder of an engine. Such systems and methods may include determining a standard deviation for a crank angle location in a chamber of the engine, determining a standard deviation of the peak pressure in a chamber of the engine. If the standard deviation for a crank angle location is greater than a threshold value for the standard deviation for a crank angle, or if the standard deviation for the peak pressure is greater than a threshold value for the standard deviation of the peak pressure, an engine cylinder cut out check may be performed to identify one or more misfiring cylinders.

The disclosure describes systems and methods of detecting a misfire in a cylinder of an engine. Such systems and methods may include determining a standard deviation for a crank angle location in a chamber of the engine, determining a standard deviation of the peak pressure in a chamber of the engine. If the standard deviation for a crank angle location is greater than a threshold value for the standard deviation for a crank angle, or if the standard deviation for the peak pressure is greater than a threshold value for the standard deviation of the peak pressure, an engine cylinder cut out check may be performed to identify one or more misfiring cylinders.

A circuit and a method for a digital inlet valve having a shutter moveable between a closed and an open position and actuated by a linear electromagnetic actuator including a movable needle located inside a coil winding connected to a power source by a first electronic switch. An electric current is supplied to the coil winding. A parameter indicative of a movement of the needle is monitored. The electric current supply is adjusted when the monitored parameter exceeds a predetermined value.

A method of protecting a direct injection fuel injector in a multi-fuel engine, the method includes selectively operating the multi-fuel engine with a directly injected fuel introduced through the direct injection fuel injector and a second fuel; when fuelling the multi-fuel engine with the second fuel, selectively commanding a fuel system protection technique when determining that the direct injection fuel injector requires cooling, an age of directly injected fuel is above a predetermined value, transmission status has changed, an engine shutdown event has occurred and a global positioning system signal indicates an engine shutdown event will occur; wherein the fuel system protection technique includes commanding that the directly injected fuel be a portion of total fuel consumed and reducing quantities of the second fuel that is injected so that total fuel consumed equals a desired amount of fuel measured on an energy basis.

A method and apparatus for identifying a faulty fuel injector is disclosed. The fuel injectors are commanded in sequence to inject a fuel quantity. A plurality of values of a crankshaft rotational speed is measured during the combustion of the injected the quantities. The measured values are processed to calculate a respective unbalancing value representative of the fuel quantity injected by the fuel injector. An average value of the calculated unbalancing values is calculated and subtracted from each of the unbalancing values to obtain a respective adjusted unbalancing value. The standard deviation of the adjusted unbalancing values is calculated and multiplied with each of the adjusted unbalancing values to obtain a respective corrected unbalancing value. The corrected unbalancing values are compared with a predetermined threshold value thereof, and a faulty fuel injector is identified if the corresponding corrected unbalancing value exceeds the predetermined threshold value.

A method of controlling a fuel system includes determining the opening of a pressure relief valve and initiating a reseat strategy for the valve. The fuel system comprises a source of high pressure fuel and a pressure relief valve having at least one inlet fluidly coupled to the source of high pressure fuel and at least one outlet. The pressure relief valve has a closed position and at least one open position in which fuel is able to pass from the inlet to the outlet. The method comprises the steps of continuously measuring the pressure of the fuel in the fuel source, determining whether the pressure relief valve is in an open position, and generating an open signal if it is determined that the pressure relief valve is in an open position.