Methods and systems are provided for controlling a fuel system of a vehicle to diagnose whether a fuel filter is functioning as desired. In one example, a method may include, in response to a fuel rail pressure decreasing below a threshold pressure while an engine of the vehicle is running, diagnosing whether degradation of fuel injectors or a fuel pressure regulator of the vehicle has occurred while the engine is not running. Then, only if degradation of the fuel injectors and fuel pressure regulator has not occurred, a fuel filter cleaning routine is performed.

Methods and systems are provided for injector balancing without disabling a cam actuated high pressure fuel pump. In one example, one of a plurality of cam lobes of the pump is selectively and sequentially disabled while a group of injectors are concurrently operated to learn a pressure drop across each injector. The selection of the injectors is based on the identity and stroke timing of the disabled cam lobe.

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 reducing errors in estimated fuel rail pressure incurred at the time of a scheduled injection event due to engine-driven cyclic fuel rail pressure changes. In one example, a pulse-width commanded during a scheduled injection event is determined as a function fuel rail pressure samples collected over a moving window that is customized for the corresponding fuel injector. In another example, the commanded pulse-width is determined as a function of an average fuel rail pressure sampled during a quiet zone of injector operation and predicted fuel rail pressure altering events occurring between the quiet zone and the scheduled injection event.

Methods and systems are provided for reducing errors in estimated fuel rail pressure incurred at the time of a scheduled injection event due to engine-driven cyclic fuel rail pressure changes. In one example, a pulse-width commanded during a scheduled injection event is determined as a function fuel rail pressure samples collected over a moving window that is customized for the corresponding fuel injector. In another example, the commanded pulse-width is determined as a function of an average fuel rail pressure sampled during a quiet zone of injector operation and predicted fuel rail pressure altering events occurring between the quiet zone and the scheduled injection event.

A method and system for correcting a fuel injection amount that injects fuel may include applying a current value for injecting a target fuel amount and injecting fuel under a driving condition in which fuel injection is blocked; determining a frequency analysis value for a pressure signal of the fuel pressure rail when the fuel is injected; determining a fuel amount difference corresponding to a difference value between the frequency analysis value and a reference frequency analysis value stored in a data storage in advance; and correcting a current value of the injector which is applied to inject the target fuel amount to remove the fuel amount difference.

Methods and systems are provided for reducing errors in estimated fuel rail pressure incurred at the time of a scheduled injection event due to engine-driven cyclic fuel rail pressure changes. In one example, a pulse-width commanded during a scheduled injection event is determined as a function fuel rail pressure samples collected over a moving window that is customized for the corresponding fuel injector. In another example, the commanded pulse-width is determined as a function of an average fuel rail pressure sampled during a quiet zone of injector operation and predicted fuel rail pressure altering events occurring between the quiet zone and the scheduled injection event.

Methods and systems are provided for conducting an evaporative emissions test on a fuel tank and an evaporative emissions system in a vehicle. In one example, pressure for the evaporative emissions test is provided by inductive heating of the fuel tank while the vehicle undergoes an inductive battery charging operation. In this way, evaporative emissions testing may be enabled under conditions wherein sufficient heat rejection from the engine to the fuel tank is not available, and further enables evaporative emissions testing without the use of an external pump thus eliminating additional costs, and reducing the space occupied in the vehicle for evaporative emissions testing diagnostics.

A method for monitoring an injector for common-rail injection systems includes detecting an electrical signal indicative of a deformation of a diaphragm of a head plate having a reaction surface facing a control chamber of the injector and processing the deformation signal to determine characteristic data of the operation of the injector.

A fuel injector test machine is provided such that an injector is fixed on a test feature with a manually operable clamp.