Abstract: An emission control system has a catalyst and a sensor responding to a component of exhaust gas. In order to speed warming up the catalyst, the emission control system increases the amount of heat dissipated by exhaust gas. A diagnosis of the emission control system is carried out by determining whether the amount of heat dissipated by exhaust gas is sufficient or insufficient. The amount of heat dissipated by exhaust gas is represented by the length of time to an activated state of the sensor. In the diagnosis, the amount of heat generated by a heater provided in the sensor is taken into consideration. The diagnosis can also be carried out before and after the warming up the catalyst. The heater can also be deactivated. Detection of an abnormality of a secondary air control system can be based on a component of exhaust gas. If the amount of heat dissipated by exhaust gas is found insufficient, additional control can be executed.

Abstract: A fuel injection system for an internal combustion engine introduces, via an air passage bypassing a throttle valve, a portion of intake air flowing in an induction system of the engine to an area where fuel is injected from a fuel injection valve, so as to facilitate atomization of the injected fuel. The air passage includes therein a flow control unit for opening and closing the air passage. During an engine idling, a total opening time of the air passage effected by the flow control unit is variably controlled for adjusting a supply mount of the intake air through the air passage so as to realize a target idling engine speed. As a result, the intake air fed through the air passage works not only to facilitate the atomization of the injected fuel, but also to control the idling engine speed to the target value.

Abstract: A carbon fiber-reinforced carbon composite material, wherein carbon fibers are oriented substantially in the thickness direction, the ratio of the thermal conductivity in the thickness direction to the thermal conductivity in a direction perpendicular to the thickness direction is at least 2, and the thermal conductivity in the thickness direction is at least 3 W/cm.multidot..degree.C.

Abstract: A fuel injection device increases an increment value of fuel after cut-off of assist air so that the air/fuel ratio for combustion can be held constant to stabilize the idling rotational speed. The device has control means for controlling, based on various detection signals indicative of an engine cooling water temperature, an engine rotational speed, an amount of intake air, etc., a valve-opening time of a fuel injection valve in accordance with a predetermined control program, and also controlling an on/off control valve for cutting off air supplied to fuel atomizing means. Fuel incrementing means increases an amount of liquid fuel supplied to the fuel injection valve depending on opening/closing of the on/off control valve and the temperature of engine cooling water. When the on/off control valve is closed and an engine is in a state of steady operation, the increment value of the liquid fuel supplied to the fuel injection valve can be gradually increased by the fuel incrementing means.