A method can include controlling, by at least one controller, an amount of hydrocarbons provided upstream of a diesel oxidation catalyst. The method can include determining, by the at least one controller, a first temperature of exhaust gas at an inlet of the diesel oxidation catalyst. The exhaust gas can be produced from combustion of fuel. The method can include determining, by the at least one controller, a second temperature of the exhaust gas at an outlet of the diesel oxidation catalyst. The method can include calculating, by the at least one controller, a lower heating value of the fuel based on the first temperature, the second temperature, the amount of hydrocarbons, and a flow rate of the exhaust gas. The method can include estimating, by the at least one controller, a percentage of biodiesel in the fuel based on the lower heating value.

A fuel tank containing a fuel and oil mixture is managed to determine if the fuel and oil mixture contains the correct ratio for a motor. The fuel tank containing a fuel and oil mixture is monitored. A fuel to oil ratio is selected for the motor. A combined viscosity of the fuel and oil mixture is calculated with respect to the fuel to oil ratio, and the temperature of the fuel and oil mixture. The combined viscosity is used to determine a predetermined range of the combined viscosity. The viscosity of the fuel and oil mixture within the fuel tank is measured as a measured viscosity. If the measured viscosity of the fuel and oil mixture does not correspond with the predetermined range, then a user may be alerted that the measured viscosity does not correspond with the predetermined range.

Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.

A fuel tank containing a fuel and oil mixture is managed to determine if the fuel and oil mixture contains the correct ratio for a motor. The fuel tank containing a fuel and oil mixture is monitored. A fuel to oil ratio is selected for the motor. A combined viscosity of the fuel and oil mixture is calculated with respect to the fuel to oil ratio, and the temperature of the fuel and oil mixture. The combined viscosity is used to determine a predetermined range of the combined viscosity. The viscosity of the fuel and oil mixture within the fuel tank is measured as a measured viscosity. If the measured viscosity of the fuel and oil mixture does not correspond with the predetermined range, then a user may be alerted that the measured viscosity does not correspond with the predetermined range.

A fuel tank containing a fuel and oil mixture is managed to determine if the fuel and oil mixture contains the correct ratio for a motor. The fuel tank containing a fuel and oil mixture is monitored. A fuel to oil ratio is selected for the motor. A combined viscosity of the fuel and oil mixture is calculated with respect to the fuel to oil ratio, and the temperature of the fuel and oil mixture. The combined viscosity is used to determine a predetermined range of the combined viscosity. The viscosity of the fuel and oil mixture within the fuel tank is measured as a measured viscosity. If the measured viscosity of the fuel and oil mixture does not correspond with the predetermined range, then a user may be alerted that the measured viscosity does not correspond with the predetermined range.

A fuel tank containing a fuel and oil mixture is managed to determine if the fuel and oil mixture contains the correct ratio for a motor. The fuel tank containing a fuel and oil mixture is monitored. A fuel to oil ratio is selected for the motor. A combined viscosity of the fuel and oil mixture is calculated with respect to the fuel to oil ratio, and the temperature of the fuel and oil mixture. The combined viscosity is used to determine a predetermined range of the combined viscosity. The viscosity of the fuel and oil mixture within the fuel tank is measured as a measured viscosity. If the measured viscosity of the fuel and oil mixture does not correspond with the predetermined range, then a user may be alerted that the measured viscosity does not correspond with the predetermined range.

A fuel tank containing a fuel and oil mixture is managed to determine if the fuel and oil mixture contains the correct ratio for a motor. The fuel tank containing a fuel and oil mixture is monitored. A fuel to oil ratio is selected for the motor. A combined viscosity of the fuel and oil mixture is calculated with respect to the fuel to oil ratio, and the temperature of the fuel and oil mixture. The combined viscosity is used to determine a predetermined range of the combined viscosity. The viscosity of the fuel and oil mixture within the fuel tank is measured as a measured viscosity. If the measured viscosity of the fuel and oil mixture does not correspond with the predetermined range, then a user may be alerted that the measured viscosity does not correspond with the predetermined range.

In a control system for an internal combustion engine that can use a plurality of kinds of fuel including compressed natural gas, the invention prohibits a changeover from CNG to another fuel from being made in a period from a time when CNG is used for the first time after the start of the internal combustion engine to a time when it is determined that properties of CNG do not need to be learned, or a period from the time when CNG is used for the first time after the start of the internal combustion engine to a time when a processing of learning the properties of CNG ends.

Methods and systems are provided for estimating an amount of exhaust gas recirculation (EGR) from an exhaust passage into an intake passage of an engine system by operating an exhaust oxygen sensor in a variable voltage (VVs) mode. In one example, a method includes during operation of an exhaust oxygen sensor in the VVs mode where a reference voltage of the exhaust oxygen sensor is adjusted from a lower, first voltage to a higher, second voltage, adjusting engine operation based on the EGR amount estimated based on an output of the exhaust oxygen sensor and a learned correction factor based on the second voltage. In this way, the exhaust oxygen sensor may be used to correct for variations arising due to changing fuel composition and ambient humidity and further used to estimate the amount of EGR being recirculated in the system, thereby enhancing engine fueling and EGR control.

Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.