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The fuel injector is located in the inlet manifold of the engine and sealed in between the manifold and fuel supply rail by rubber seals. A fuel pump pressurizes the system to normally about 2.5 - 3 bar.

The Engine Control Unit (ECU) determines the opening duration required for that combustion stroke. A current is transmitted to the solenoid of the injector.

The solenoid will magnetically lift the pintle valve needle from the seat of the injector, varying between 60 -100 microns. While the valve is raised, the pressurized fuel is forced through the orifice gap in the bottom of the injector, on to the pintle head and form a spray pattern shape as nominated by the head design.

The injector will remain open for anywhere between 1 – 20 milliseconds, at a frequency of 3 – 125 Hz, depending on the engines requirements. When the current is stops, a small coil spring pushes the valve needle to the pintle seat and stops any further fuel from passing through. 

The Injector Valve has the finest tolerances which in turn necessitates a clean and unobstructed flow.

Problems occur when the lacquers/chemicals in fuel cause a buildup of contamination, both inside the injector and on the pintle valve.

Filter blockage and internal contamination can reduce the injector flow rate by as much as 30%.

Although actual dismantling of an injectors internals is not possible, in most cases servicing injectors can return them to acceptable level of functionality.


At West Performance we are equipped with the latest ASNU service and diagnostic equipment. Including top and feed and the latest GDI injectors.  

Typical issues associated with malfunctioning injectors range from:

  • Lack of power.

  • Engine starting issues.

  • Poor fuel economy

  • Lack of smooth running 

  • Possible non-starting of engine. 

Spray Pre Service.JPG

Before Service

After Service

Vol Pre Service.JPG

Using ASNU injector servicing module including pulsed ultrasonic cleaning, a majority of injectors can be recovered.

Vol Result.JPG
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