In some embodiments, a vehicle includes a temperature monitoring controller. The temperature monitoring controller is a processor, control module, or other suitable hardware that is configured to receive temperature sensor values from an engine control module (ECM) when an ignition bus is in a powered on state, and to decide when the engine should be automatically started in order to maintain a temperature above a low temperature threshold. The temperature monitoring controller periodically causes an ignition bus of the vehicle to be placed in the powered on state when the engine is shut down in order to collect temperature sensor values. The temperature monitoring controller determines whether to automatically start the engine, and if not, determines how long to wait before collecting temperature sensor values again based on a rate of change of the temperature sensor values.

Methods and systems are provided for an engine to infer fuel temperature from a measured rate of change in a pressure of a fuel passage between a low pressure fuel pump and a high pressure fuel pump during certain operating conditions, including when the low pressure fuel pump is switched off. The operation of the low pressure fuel pump may be adjusted responsively to a change in the inferred fuel temperature.

Methods and systems are provided for characterizing aged fuel, which loses volatility over time. In one example, a method may include estimating a fuel vapor pressure during an engine cold start using a pre-determined fuel distillation curve and adjusting one or more combustion parameters based on the estimated fuel vapor pressure. Because the fuel vapor pressure directly relates to the fuel volatility, adjusting the one or more combustion parameters based on the estimated fuel vapor pressure may reduce aged fuel-related engine performance degradation, such as hesitation and emissions during cold start.

Methods and systems are provided for diagnosing a vehicle fuel system for a presence or absence of undesired evaporative emissions. In one example, a method comprises evacuating the fuel system of a vehicle to a variable vacuum target as a function of a volatility of fuel in a fuel tank positioned in the fuel system and a loading state of a fuel vapor storage canister configured for capturing and storing fuel vapors from the fuel tank. In this way, analysis of a pressure-bleedup portion of the diagnostic may be more reliable and completion rates of the diagnostic may be improved, while conducting the test in an environmentally fashion.

The purpose of the present invention is to provide a control device for an internal combustion engine with which it is possible to favorably control an engine even if there could occur a difference in temperatures of fuel injected into respective cylinders. The present invention is a control device for an internal combustion engine, for controlling an internal combustion engine provided with fuel injection valves for directly injecting fuel respectively to a plurality of cylinders, wherein: the control device is provided with a fuel temperature acquiring means for acquiring respective temperatures of fuel injected to each of the cylinders; and at least one of a fuel injection valve control amount, ignition control amount, and intake and exhaust valve control amount of each of the cylinders is set in accordance with the respective temperatures of fuel acquired by the fuel temperature acquiring means. Alternatively, the present invention is a control device for an internal combustion engine, for controlling an internal combustion engine provided with fuel injection valves for directly injecting fuel respectively to a plurality of cylinders, wherein the control device is provided with a valve-closing time detecting means for detecting a valve-closing time of a valve body of each of the fuel injection valves, and a fuel temperature estimating means for estimating the temperature of fuel on the basis of the valve-closing duration of the valves detected by the valve-closing time detecting means.

A method for starting an internal combustion engine with a fuel tank and a low-pressure pump which pumps gasoline out of the fuel tank at a low-pressure to a high-pressure pump that pumps the gasoline at a high-pressure to injectors of the internal combustion engine. An electronic controller is provided for controlling and/or regulating the low-pressure pump, the high-pressure pump, and the injectors. After a start pulse for the internal combustion engine, the method: checks whether a formation of vapor bubbles in the gasoline is possible on the low-pressure side during a hot start. If not possible, then the normal low-pressure is set. If possible, then a low pressure which is high enough that the formation of vapor bubbles is not possible on the low-pressure side is set, and the normal low-pressure is set after a period of time. The problem of vapor bubble formation is prevented in an inexpensive or cost neutral manner via the method.

Methods and systems are provided for temperature control of a high pressure pump (HPP) of a direct injection system. When direct injection is disabled, the HPP and the associated direct injectors are intermittently operated when the HPP temperature rises above a modeled threshold temperature. The HPP and injectors are operated until the HPP temperature falls below the modeled threshold temperature.

A method is described for operating an electric fuel pump constituting a low-pressure pump in a fuel supply system for an internal combustion engine, having a high-pressure reservoir and a high-pressure pump, of a motor vehicle. The electric fuel pump is operated at least temporarily, during a time period during which the internal combustion engine is switched off during operation of the motor vehicle, with a minimum value for a control application variable for the electric fuel pump.

A fuel system for a vehicle propulsion system includes a fuel temperature determination module that determines a temperature of a fuel, a fuel pressure determination module that determines a pressure of the fuel, a prime determination module that determines whether the determined fuel temperature is above a vaporization temperature on a predetermined distillation curve and the fuel pressure is below the predetermined distillation curve at the determined fuel temperature, and a controller programmed to command operation of a fuel pump in response to the prime determination module determining that the determined fuel temperature is above a vaporization temperature on the predetermined distillation curve and the fuel pressure is below the predetermined distillation curve at the determined fuel temperature.

Disclosed is a method for limiting fuel leakage from at least one injector in an engine of a motor vehicle, the engine being stopped and the motor vehicle ignition circuit being switched off, the injector being supplied with fuel via a fuel rail which is pressurized during operation, the pressurization persisting for a certain period when the engine has been stopped and the ignition circuit switched off, leading to leakage of fuel through the injector. The injection rail is subjected to forced cooling following the stoppage of the engine with the motor vehicle ignition circuit switched off, which is sufficient to reduce the pressure, the forced cooling continuing until the pressure in the rail is close to atmospheric pressure.