Diagnostic Tests: Injectors: Operation

• The injectors are electromagnetic-valve-equipped injection nozzles that function to inject fuel based upon injection signals from the engine control unit.
• Because the surface area of the injection ports is fixed and because the pressure of the fuel relative to the pressure within the manifold is also regulated to a fixed pressure, the amount of fuel injection by injectors is determined by the length of time that the needle valve is open, or, in other words, by the length of time of current flow to the solenoid coil.
• Battery power is supplied, by way of the control relay, to the injectors. When the engine control unit switches on the power transistor within the unit and current flows to the solenoid coil, the injectors open and fuel is injected. See Fig 1 .

Fig 1: Identifying Injectors Circuit

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.