A method is disclosed of controlling operation of a fuel injector in response to measuring a quantity of fuel injected by the fuel injector from a fuel accumulator to an engine cylinder during operation of a fuel pump that delivers fuel to the accumulator, comprising: determining an average pressure of the fuel accumulator during a first time period before a fuel injection event; predicting a mass of fuel delivered to the fuel accumulator during a pumping event (Q.sub.pump); determining an average pressure of the fuel accumulator during a second time period after the fuel injection event; estimating a leakage of fuel; computing the injected fuel quantity by adding the average pressure during the first time period to Q.sub.pump, and subtracting the average pressure during the second time period and the leakage; and using the computed injected fuel quantity to control operation of the fuel injector.

Disclosed is a method for controlling an engine torque for a diesel engine, characterized in that the engine torque control is implemented in an injection system. The injection system in question includes a high-pressure pump controlled by an engine control unit, the high-pressure pump supplying a fuel supply rail, the pump being dimensioned to be capable of delivering a capacity volume of compressible fuel for each combustion cycle of the diesel engine. It also includes a pressure sensor for measuring the pressure of the fuel in the fuel rail.

The disclosure relates to a method for operating an internal combustion engine which has at least one injector and in which a correction of fuel injection quantity is implemented. For the correction of the fuel injection quantity, different properties of the injector in the ballistic working range thereof and in the linear working range thereof are evaluated. A total injection quantity of the injector demanded in an operating cycle is divided into a number of smaller, equal partial injection quantities implemented as partial pulses, and an evaluation of the pressure drops triggered by the partial pulses is performed in the correction of the fuel injection quantity. The disclosure furthermore relates to a device for operating an internal combustion engine which has at least one injector and in which a correction of the fuel injection quantity is implemented.

Various embodiments of the present disclosure relate to methods and systems for measuring an injected fuel quantity during multipulse injection events in a common rail of a fuel system including a fuel pump to supply fuel to the common rail. The method, using a control unit, determines if each of the multipulse injection events in a normal operating condition includes a pilot pulse, in response to determining that the pilot pulse is included, obtaining an enforced separation value between the pilot pulse and the main pulse to emulate a single-pulse injection; while the fuel pump is temporarily shut off, performing a temporary enforced separation on a fraction of the multipulse injection events; measuring a pressure change in the common rail during the temporary enforced separation; and resuming the normal operating condition of the multipulse injection events after the pressure change is measured.

Methods and systems are provided for a fuel injector diagnostic. In one example, a method may include modifying an injection pattern to determine a relative fuel mass error of an injector. A fuel injector correction may be determined based the relative fuel mass error.

A method is disclosed of controlling operation of a fuel injector in response to measuring a quantity of fuel injected by the fuel injector from a fuel accumulator to an engine cylinder during operation of a fuel pump that delivers fuel to the accumulator, comprising: determining an average pressure of the fuel accumulator during a first time period before a fuel injection event; predicting a mass of fuel delivered to the fuel accumulator during a pumping event (Q.sub.pump); determining an average pressure of the fuel accumulator during a second time period after the fuel injection event; estimating a leakage of fuel; computing the injected fuel quantity by adding the average pressure during the first time period to Q.sub.pump, and subtracting the average pressure during the second time period and the leakage; and using the computed injected, fuel quantity to control operation of the fuel injector.

Methods and systems for adjusting fuel injector operation according to changes in fuel pressure during inter-injection periods are described. The inter-injection period may be before and after fuel is injected to an engine. The methods and systems described herein may be suitable for direct and port fuel injectors.

Methods and systems are provided for balancing fuel delivery amongst all engine fuel injectors. In one example, a method may include selectively adjusting an injection timing of one or more fuel injectors of a plurality of fuel injectors to increase an inter-injection period between two consecutive fuel injections in response to a request to balance amounts of fuel injected by the plurality of fuel injectors.

A method for injecting a predetermined total fuel quantity via multiple injections using a fuel injector having a solenoid drive for an internal combustion engine of a motor vehicle is disclosed. The method includes determining a first target injection quantity to be injected per injection to inject the total fuel quantity throughout a series of consecutive injections; and performing a first subseries of consecutive injections, where the fuel injector is actuated according to the first target injection quantity. The method also includes determining a first fuel quantity injected during the first subseries of injections; determining a second target injection quantity to be injected per injection in a second subseries of consecutive injections, to inject the total fuel quantity throughout the first subseries and the second subseries of consecutive injections; and performing the second subseries of injections. The fuel injector is actuated according to the second target injection quantity.

A computer-implemented method for training a data-based point in time determination model for ascertaining an opening or closing point in time of an injection valve of an internal combustion engine, based on a sensor signal. The method includes: providing a set of training data sets from a measurement of the internal combustion engine by scanning the sensor signal of a sensor of the injection valve on a test stand, the training data sets assigning a time indication of the opening or closing point in time to an evaluation point time series; assigning a difficulty value to each training data set; classifying the training data sets into a number of difficulty classes corresponding to their respective difficulty value; ascertaining new training data sets as a function of the training data sets assigned to each difficulty class; training the model with the set of new training data sets.