Abstract: A low-octane fuel and a high-octane fuel stored in a low-octane fuel tank (5) and a high-octane fuel tank (7), both having known octane numbers, are injected from fuel injection valves (13a, 13b) into an intake port (12) at a mixing proportion that achieves a standard octane number set in accordance with the engine operation state. If knocking occurs during a predetermined steady engine operation state, the knocking is detected by a knock sensor (10b) and, corresponding to the knocking, the ignition timing is retarded from a basic ignition timing. A deviation in octane number is determined from the amount of ignition timing retardation with reference to a map, and is then corrected by the intake air pressure. On the basis of the corrected deviation in octane number, a deviation in the mixing proportion of the high-octane fuel is determined with reference to a map.

Abstract: From the start of the engine to the detection of an engine speed peak, a control parameter (e.g., ignition timing) different from an air intake rate relating to an engine output is set to a value at which the engine output decreases than at an idling value. After detection of the peak, the control parameter is adjusted to the idling value.

Abstract: There is provided a spark ignition engine having a low RON fuel tank to store a low RON fuel and a high RON fuel tank to store a high RON fuel, which can detect storage failure. It is judged that the two kinds of fuels are properly stored when differences between the base ignition timing and the practical ignition timing at different loads are identical. When the differences are not identical, for example, it is judged that the high RON fuel is stored both in the two fuel tanks when a difference between the proper mix fuel knocking-occur ignition timing and the practical ignition timing is decreased as the load is increased.

Abstract: A method for reducing the magnitude of a knock retard angle in a vehicle having a quantity of fuel and a system for determining the quantity of fuel. The method determines a previous fuel quantity and a present fuel quantity, determines from said present fuel quantity and said previous fuel quantity whether the quantity of fuel has increased; and decreases the magnitude of the knock retard angle upon determining the quantity of fuel has increased.

Abstract: A control device for a spark-ignition engine, in which a mixture in a combustion chamber is fired by compression ignition in a part-load range under warm-running conditions, includes an EGR controller incorporating a valve operation controller for controlling internal EGR of hot burned gas and a cold EGR controller for controlling external EGR of cold burned gas. The EGR controller performs EGR control operation to leave the hot EGR gas in the combustion chamber in a lower-load, lower-speed region within a compression ignition combustion range and to introduce the cold EGR gas into the combustion chamber in a higher-load, higher-speed region within the compression ignition combustion range. The control device further includes a firing assist unit for inducing the compression ignition at least when ignitability of the mixture decreases due to introduction of the cold EGR gas in the compression ignition combustion range.

Abstract: A knock control system for an internal combustion engine having a plurality of cylinders. Operation of the engine is switchable between a partial-cylinder operation for operating some of the cylinders and an all-cylinder operation for operating all of the cylinders. A determination threshold for determining knocking is set according to an output signal from the knock sensor. A level of the output signal from the knock sensor is compared with the determination threshold, and occurrence of knocking is determined according to a result of the comparison. The determination threshold used during the partial-cylinder operation is set to a value less than a value of the determination threshold used during the all-cylinder operation.

Abstract: A method for controlling the compression ratio &egr; in a supercharged combustion engine. The latter is provided with a control device in which a maximum final compression temperature T2,max is ascertained, and, within the framework of a precontrol, an optimum efficiency compression ratio &egr;opt is ascertained. The knock limit is determined from the compression ratio &egr;, to which it corresponds, and which is ascertained from the precontrol. As a function of the efficiency curve in the characteristics map &eegr;=f, a further change occurs in compression ratio &ggr; or a setting back of the change in compression ratio &egr;. The values learned for &egr; and the ignition angle as a function of the operating point are permanently stored in a characteristics map to which the engine control has access.

Abstract: Methods, apparatus, and systems for distinguishing between compression and exhaust strokes of a four-cycle engine is provided. A first ionization time of a spark plug for a known cylinder is measured on a first engine stoke. A second ionization time of the spark plug is measured on a second engine stroke. The second ionization time is compared to the first ionization time. It is determined that the engine stroke with the greater ionization time is a compression stroke.

Abstract: Disclosed is a system and method for processing crank angle signals. The system comprises a crank angle sensor for converting a rotation of a crankshaft into analog signals; a switching circuit for converting the analog signals into crank angle signals; a timer/counter for detecting a number of pulses and tooth periods of the crank angle signals; a phase sensor for converting a rotation of a camshaft into cylinder identity signals and outputting the cylinder identity signals; and an electronic control unit for receiving the crank angle signals and the cylinder identity signals and using the signals to determine cylinder identity and rpm.

Abstract: The present invention is a method of ignition advance correction of an internal-combustion engine according to the composition variation of the natural gas contained in a tank and supplying the engine. A methane number relative to the natural gas filling the tank is determined and an ignition advance correction value is deduced from the number. According to the invention, a correlation is established between the methane number described above, an air-fuel ratio R for a stoichiometric combustion and the gas flow variation required to reach a reference working point of the engine after the composition variation of this gas.