Embodiments described herein relate to systems and methods of operating internal combustion (IC) engines by combusting various fuel chemistries therein. Specifically, engines described herein can operate a wide range of fuel chemistries with varying molecular formulas. The chemical compositions of the fuels described herein make them more difficult to ignite than long chain hydrocarbons (i.e., fuels that include 6 or more carbon atoms in a molecule). In some embodiments, engines described herein can combust fuels that have the chemical properties of alcohols. In some embodiments, engines described herein can combust fuels that include hydroxide groups. Examples of such fuels include methanol and/or ethanol. In some embodiments, engines described herein can combust natural gas. These fuel chemistries are difficult to ignite, particularly at low temperatures and during initial engine startup. Systems and methods described herein address these ignition difficulties, particularly in diesel engine architectures.

According to one or more embodiments, an internal combustion engine may be operated by a method which includes one or more of injecting a first fuel and a second fuel into an engine cylinder to form a fuel mixture, and combusting the fuel mixture with a spark plug to translate a piston housed in the engine cylinder and rotate a crank shaft coupled to the piston. The first fuel may comprise a greater octane rating than the second fuel. A target CA50 may correspond to a minimum in specific fuel consumption of the fuel mixture. The spark plug may initiate combustion at a time such that the internal combustion engine operates with an operational CA50 that is within 20 degrees of the target CA50.

A vehicle includes an engine and a controller programmed to, responsive to an estimated oil dilution level of the engine exceeding a first threshold, issue commands such that regenerative braking is inhibited to increase a temperature of the engine, and responsive to the estimated oil dilution level falling below the first threshold, discontinue issuing the commands.

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 calculating a fuel aging of fuel in a fuel tank. In one example, a method may include alerting a vehicle operator and/or adjusting engine operating parameters in response to a fuel aging being greater than a threshold aging.

A blended fuel injection control method may include a cold-starting determination step in which a controller determines whether a cold-starting condition is satisfied on the basis of output values that can be obtained by a vehicle; a detection step in which the controller detects the content of ethanol in blended fuel of gasoline and ethanol when determining the cold-starting condition is satisfied; and a first injection control step in which the controller controls the blended fuel to be injected selectively in one of a Multi-Point Injection (MPI) mode, an MPI & GDI mode combining MPI and Gasoline Direct Injection (GDI) modes, and a GDI mode in accordance with the content of ethanol in the blended fuel until an engine RPM reaches an early peak RPM in engine-cranking.

A fuel injector for an internal combustion engine includes a fuel injection valve, a heater, and a controller. The fuel injection valve is configured to supply fuel to the internal combustion engine. The heater is configured to heat the fuel in the fuel injection valve. The controller is configured to: control the fuel injection valve to stop supplying the fuel to the internal combustion engine, control the heater to execute or stop heating the fuel in the fuel injection valve, and control the fuel injection valve to prohibit the stop of supplying the fuel during execution of the heating by the heater.

An engine control unit of a multi-fuel is provided. The engine consumes a mixture of a first fuel and a second fuel. The engine control unit includes hardware circuitry that includes one or more processors configured to calculate an autoignition delay of the mixture of the air and the second fuel based on current operating conditions of the multi-fuel engine. The one or more processors also are configured to calculate an upper limit on an amount of the second fuel that is supplied to the multi-fuel engine based on the autoignition delay that is calculated.

An internal combustion engine control device for a dual-injection internal combustion engine acquires first and second increase values, which are fuel increase ratios according to respective alcohol concentrations of a fuel injected by cylinder injection and a fuel injected by port injection. The control device determines a basic total injection amount of fuel that should be supplied to each cylinder in the case where the alcohol concentration of the fuel is zero. An amount of fuel injected from a cylinder injection valve is determined as if the alcohol concentration of the fuel were zero. A total injection amount is to correspond to an amount in accordance with the basic total injection amount and both, the first increase value and the second increase value, so that the increase in injected fuel amount is borne by port injection.

A control device of the present invention is applied to an engine provided with a fuel injection valve which directly injects fuel into a combustion chamber. The control device includes a pre-ignition prediction unit which predicts occurrence of pre-ignition when the engine is started; and an injection control unit which causes fuel to be injected in an expansion stroke from the fuel injection valve when occurrence of pre-ignition is predicted by the pre-ignition prediction unit. Thus, it is possible to prevent pre-ignition without lowering the effective compression ratio.