Fuel Injector Operation

The Powertrain Control Module (PCM) controls the amount of fuel the fuel injector supplies to each cylinder by controlling the ON time (length of pulse) of the fuel injector. The PCM also controls the timing of the delivery of the fuel by the fuel injector. The timing and pulse of the fuel injector is carefully calculated with input from the various information sensors. Precise control ensures that a suitable air/fuel mixture is supplied to the engine for every driving condition.

There are two types of injection timing. One is synchronous injection and the other is asynchronous injection. Synchronous injection is when the injection of fuel occurs at the same time (synchronous) as the ignition signal (or the signal from the Camshaft Position [CMP] Sensor). Asynchronous injection is when the injection of fuel occurs independently of the ignition signal (or the signal from the Camshaft Position [CMP] sensor).

The PCM first calculates the volume of air and then factors in the engine speed in order to determine the correct timing of the fuel injector. The PCM also applies certain compensations that are based on the information provided by the various information sensors that detect the state of the engine and the current driving conditions.