According to the design of the injector nozzle, injectors can be divided into pin-type and hole-type.
According to different coil resistance values, injectors can be classified as high-resistance and low-resistance types.
Depending on the application, injectors can be divided into types such as MPI and SPI.
According to the fuel supply position, injectors can also be divided into top-feed and side-feed types.
During the fuel injection process, the injector plays a crucial role:
Essentially, the injector is a solenoid valve, and its operating status is controlled by pulse signals from the electronic control unit.
When the injector is energized, the electromagnetic coil generates electromagnetic force, pulling the armature and needle valve upward, thereby opening the injector and allowing fuel to be sprayed into the intake port or pipe through the nozzle.
Once power is cut off, the electromagnetic force disappears, and the armature and needle valve reseal the nozzle under the action of the return spring, stopping the fuel injection.
The energizing and de-energizing of the injector are precisely controlled by the electronic control unit through pulse signals.
The amount of fuel injected depends on the width of the pulse, i.e., the duration of the fuel injection.
The lift of the needle valve is usually controlled around 0.1 mm, while the injection duration is maintained within the range of 2–10 ms.
When testing an injector, if it fails to work properly, you can first check the signal status of the injector harness connector with a test light before starting the engine. If the test light flashes, it indicates that the injector control system is operating normally, and the fault may lie with the injector itself. At this point, a multimeter can be used to measure the resistance of the injector's electromagnetic coil. If the resistance value is normal, the injector may be clogged or the needle valve stuck due to carbon deposits and gum in the fuel, requiring cleaning, repair, or replacement. If the resistance value is abnormal, the injector must be replaced.
If the test light does not illuminate, it indicates a problem with the injector's control system or related circuits. In this case, the injector circuit should be checked first. Only after confirming that the external circuit is functioning properly can a fault in the electronic control unit be further assessed. ...
