Abstract: Systems and methods for improving fuel injection of an engine that includes a cylinder receiving fuel from a direct fuel injector are disclosed. In one example, a transfer function or gain of a direct fuel injector is adjusted in response to an exhaust lambda value and a first pulse width of two pulse widths provided to an injector of a cylinder during a cylinder cycle.

Abstract: A method for a PFDI engine may comprise, during a first condition, comprising direct-injecting fuel to the PFDI engine, estimating a fuel vapor pressure, and setting a fuel lift pump pressure greater than the fuel vapor pressure by a threshold pressure difference, and during a second condition, comprising port-fuel-injecting fuel to the PFDI engine, setting a DI fuel pump command signal greater than a threshold DI fuel pump command signal without supplying fuel to a DI fuel rail.

Abstract: Methods are provided for finding the bulk modulus of a fuel used in the direct injection system of an internal combustion engine. A method is needed to continuously monitor and reliably calculate the fuel's bulk modulus during engine operation on-board the vehicle, where the fuel's bulk modulus may be used to infer the ratio of fuels in a fuel mixture or determine the density of supercritical propane when propane is used as the injected fuel. To find the fuel's bulk modulus on-board a vehicle, methods are proposed that involve monitoring and recording fuel rail pressures, high pressure pump duty cycles, and fractional liquid volume pumped values in order to find zero flow relationships.

Abstract: Methods are provided for controlling a solenoid spill valve of a direct injection fuel pump, wherein the solenoid spill valve is energized and de-energized according to certain conditions. A control strategy is needed to operate the direct injection fuel pump when small fractional trapping volumes are commanded, wherein a small amount of fuel is compressed and sent to the direct injection fuel rail. To maintain reliable and repeatable solenoid spill valve behavior for small fractional trapping volumes, methods are proposed that involve energizing the solenoid spill valve for a minimum angular duration below a trapping volume fraction threshold.

Abstract: Systems and methods are provided for a high-pressure fuel pump to mitigate audible ticking noise associated with opening and closing of a digital inlet valve of the high-pressure pump. To reduce the ticking noise associated with the high-pressure pump when the engine is idling, a solution is needed that is simple and does not involve retrofitting the fuel system with noise, vibration, and harshness countermeasures to mask the noise. Pressure devices and associated operation methods are provided that involve adding a combination of several check valves, an accumulator, and a flow control valve with weep channels to allow the digital inlet valve to be deactivated during engine idling as defined by a threshold engine speed.

Abstract: Methods are provided for detecting high pressure pump bore wear, wherein wear between a piston and bore of a pump may cause an excessive amount of fuel to leak out of a compression chamber of the pump. A reliable method is needed that involves a pump performance model that incorporates a number of physical effects and is verified by real high pressure pump test data. A method is proposed that involves comparing a target pump rate based on the pump performance model to a real fuel injection rate in order to determine if an abnormal amount of fuel may be leaking from the high pressure pump.

Abstract: Methods are provided for finding the bulk modulus of a fuel used in the direct injection system of an internal combustion engine. A method is needed to continuously monitor and reliably calculate the fuel's bulk modulus during engine operation on-board the vehicle, where the fuel's bulk modulus may be used to infer the ratio of fuels in a fuel mixture or determine the density of supercritical propane when propane is used as the injected fuel. To find the fuel's bulk modulus on-board a vehicle, methods are proposed that involve monitoring and recording fuel rail pressures, high pressure pump duty cycles, and fractional liquid volume pumped values in order to find zero flow relationships.

Abstract: Methods are provided for correct spill valve timing of a high pressure pump coupled to the direct injection system of an internal combustion engine. A method is needed to monitor and adjust spill valve timing on-board the vehicle, where spill valve timing error may result from sensors error and/or time between command signal and actuation response of the spill valve. To self-correct spill valve timing error on-board a vehicle, methods are proposed that involve monitoring and recording fuel rail pressures, high pressure pump duty cycles, and fractional liquid volume pumped values in order to find zero flow relationships.

Abstract: A method for a PFDI engine may comprise, during a first condition, comprising direct-injecting fuel to the PFDI engine, estimating a fuel vapor pressure, and setting a fuel lift pump pressure greater than the fuel vapor pressure by a threshold pressure difference, and during a second condition, comprising port-fuel-injecting fuel to the PFDI engine, setting a DI fuel pump command signal greater than a threshold DI fuel pump command signal without supplying fuel to a DI fuel rail.

Abstract: Various systems and methods are described for diagnosing injector variability in a dual fuel, multi-injector system. In one example, a single injector in one cylinder is enabled while remaining cylinders are fueled with a first fuel and subsequently, a second fuel is injected via the enabled injector into the one cylinder in a predetermined sequence and fuel rail pressure drops are measured. Further, measured pressure drop after each injection event is corrected for an increase in injector closing delay.

Abstract: Methods and systems are provided for closed loop operation of a high pressure fuel pump connected to the direct injectors of an internal combustion engine. During operation of the high pressure pump a dead zone may exist where a substantial change in the pump duty cycle does not correspond to a substantial change in the fuel rail pressure. To operate outside the dead zone, a relationship between the pump duty cycle and fuel rail pressure is learned upon completion of several pump and engine conditions, thereby improving high pressure pump operation and reducing pump degradation.

Abstract: Methods and systems are provided for a direct injection fuel pump. The methods and system control pressure within a compression chamber so as to improve fuel pump lubrication.