Fuel Injector: Description and Operation

Fig 2 Fuel Injector:

The fuel injectors are 12 ohm electrical solenoids (Fig. 2). The injector contains a pintle that closes off an orifice at the nozzle end. When electric current is supplied to the injector, the armature and needle move a short distance against a spring, allowing fuel to flow out the orifice. Because the fuel is under high pressure, a fine spray is developed in the shape of 2 streams. The spraying action atomizes the fuel, adding it to the air entering the combustion chamber. The injectors are positioned in the cylinder heads. Fuel injectors are not interchangeable between engines.

Fig 3 Fuel Injector Location -- Typical:

The injectors are positioned in the cylinder heads with the nozzle ends directly above the intake valve port (Fig. 3).


FUEL INJECTORS-PCM OUTPUT
The engines uses top feed injectors.

The Automatic Shut Down (ASD) relay supplies battery voltage to the injectors. The PCM controls the ground path for each injector in sequence. By switching the ground paths on and off, the PCM fine-tunes injector pulse width. Injector pulse width refers to the amount of time an injector operates.

The PCM determines injector synchronization from the camshaft position sensor and crankshaft position sensor inputs. The PCM grounds the ASD and fuel pump relays after receiving the camshaft position sensor and crankshaft position sensor inputs.

The PCM energizes the injectors in a sequential order during all engine operating conditions except start-up. During start-up, when the coolant temperature is below 15°C (60°F), all injectors are energized at the same time. Above 15°C, the PCM energizes the injectors in sequence. Once the PCM determines crankshaft position, it begins energizing the injectors in sequence.