Method for operating fuel injector in a computer controlled fuel injection type internal combustion engine

Method for controlling the operation of a fuel injector in a computer controlled fuel injection internal combustion engine, which engine is provided with a system for maintaining a predetermined idling rotational speed N.sub.F in accordance with the temperature of the engine and with a system for controlling the operation of the fuel injector during the deceleration condition of the engine so that the injector is de-energized when the rotational speed is higher than N.sub.cut and injector is energized when the rotational speed is lower than N.sub.RTN, said method comprising the steps of:

• storing in the computer values of N.sub.F in accordance with the temperature of the engine;
• detecting the temperature of the engine;
• reading out the value of N.sub.F corresponding to the detected temperature;
• calculating, as the value of N.sub.cut, the product of a constant positive value .alpha..sub.1 larger than 1.0 and the read out value of N.sub.F, and;
• calculating, as the value of N.sub.RTN, a product of constant positive value .alpha..sub.2 larger than 1.0 but less than .alpha..sub.1 and the read out value of N.sub.F.