Engine Overspeed Fuel Cut-Off

Engine Overspeed Fuel Cut-Off:

Engine overspeed protection is an ECU controlled function of the fuel injectors, and is determined by the engine speed sensor signal. When the engine reaches a critical rpm (just before the engines "red-line" rpm), the ECU cuts off the fuel by cutting the duty cycle to the fuel injectors. As soon as the engine speed drops below the critical rpm, the duty cycle is restored and fuel delivery returns to normal. The fuel is alternately cut and restored many times each second, at a critical rpm that is just below the engines "redline" limit. This prevents engine overspeed while maintaining torque and horsepower at the critical rpm.