On the basis of a decrease in a high-pressure detection value and a low-pressure detection value during fuel control using a CNG injector, an electronic control unit automatically switches the combustion control to combustion control using a gasoline injector even when the amount of CNG remaining is insufficient. When the first shutoff valve is forcibly switched to an closed state by inputting a forcible shutoff command of a first shutoff valve to a terminal and the combustion control using the CNG injector is performed, a switching process to the combustion control using the gasoline injector is inhibited regardless of the decrease in the high-pressure detection value and the low-pressure detection value.

To exert combustion control using a CNG injector, a first cutoff valve is opened. On condition that the first cutoff valve is opened, the presence or absence of fuel leakage in a high-pressure side path is determined based on a drop in a detected value of a pressure in the high-pressure side path (high-pressure side detected value PH). Inserting a nozzle for CNG filling into a filling opening causes a phenomenon where the high-pressure side detected value PH rises once and then drops. If the high-pressure side detected value PH rises at a specified rate or more, a CPU stops determination as to the presence or absence of a fuel leakage malfunction for a specified period of time.

A method for fuel regulation during a non-motoring operating mode of an internal combustion engine is provided. A fuel regulator employs a first fuel to regulate pressure of a second fuel. The first fuel is communicated to the fuel regulator through a first fuel circuit. The method comprises actuating a fuel injector that introduces the first fuel and the second fuel into a combustion chamber of the internal combustion engine during the non-motoring operating mode. The fuel injector is actuated with an injection command signal having a pulse width below a predetermined maximum value whereby no fuel is injected into the combustion chamber and the first fuel drains from the first fuel circuit through the fuel injector to a supply tank.

A method for controlling a dual fuel engine system includes estimating a total indicated engine load, where the total indicated engine load is based on a sum of a measured engine power and a power loss estimate. The method further includes determining a total fueling amount based on an engine speed and the total indicated engine load, where the total fueling amount includes a gas fueling amount and a diesel fueling amount. The method also includes controlling the dual fuel engine system using the total fueling amount.

A system for remotely monitoring and controlling operation of a hydro-diesel engine, having: (a) a diesel engine assembly; (b) a hydro-diesel assembly connected to the diesel engine assembly; (c) a remote control system; and (d) a remote computer system in communication with the remote control system, wherein the remote computer system is configured to instruct the remote control system to turn off operation of either: (i) the hydro-diesel assembly while permitting the diesel engine assembly to continue operation while the hydro-diesel assembly is not operating, or (ii) both the hydro-diesel assembly and the diesel engine assembly.

A method for preventing engine stall of a vehicle includes detecting, by a control portion, whether a purge control valve becomes short to ground or not, determining, by the control portion, how rich a fuel is that has flowed into the engine using an oxygen sensor when it is determined that the purge control valve becomes short to ground in the detecting step, and controlling, by the control portion, a target RPM of the engine to be increased when it is determined that the fuel is rich in the determining step.

When switching the fuel to be used for engine operation from gasoline to CNG, in a state where CNG is supplied experimentally to one cylinder serving as a judgment object and gasoline is supplied to other cylinders, whether or not CNG can be supplied to the cylinder serving as a judgment object is judged based on an amount of change Pc in fuel pressure inside a CNG delivery pipe (Step S13 to Step S16). When it is judged that a gas fuel can be supplied to all cylinders (Step S19: YES), the fuel to be used for engine operation is switched from the liquid fuel to the gas fuel (Step S20).

A device is provided, which makes it possible to perform a failure diagnostics for a filter more accurately even in the case of an internal combustion engine which is constructed to be capable of using both of gaseous fuel and liquid fuel. The device of the invention comprises judging means which judges any failure of the filter by comparing the added-up amount of the particulate matter contained in the exhaust gas as detected by a PM amount detecting sensor during a predetermined period and the added-up amount of the particulate matter contained in the exhaust gas as estimated by PM amount estimating means during the predetermined period, wherein the PM amount estimating means estimates the added-up amount of the particulate matter contained in the exhaust gas on the basis of the predetermined parameter and only a fuel injection amount of the liquid fuel out of a fuel injection amount of the gaseous fuel and the fuel injection amount of the liquid fuel.

A method for preventing engine stall of a vehicle includes detecting, by a control portion, whether a purge control valve becomes short to ground or not, determining, by the control portion, how rich a fuel is that has flowed into the engine using an oxygen sensor when it is determined that the purge control valve becomes short to ground in the detecting step, and controlling, by the control portion, a target RPM of the engine to be increased when it is determined that the fuel is rich in the determining step.

In a method for identifying a fuel type or a fuel mixture for a combustion chamber of an internal combustion engine having (i) a first intake opening connected to a first intake manifold inside which a first fuel injector is located, and (ii) a second intake opening connected to a second intake manifold inside which a second fuel injector is located, in a first method step, the first fuel injector remains closed, and in a second method step the first fuel injector is opened again and a first test fuel quantity is injected into the combustion chamber in the second method step via the first intake opening, and a second test fuel quantity is injected via the second intake opening, the first test fuel quantity and the second test fuel quantity being made up to form a predefined fuel quantity.