Injectors

Operation

The injectors are electromagnetically equipped injection nozzles that function to inject fuel based upon injection signals from the engine control module.

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 supply is supplied, by way of the multiport fuel injection relay, to the injectors. When the engine control module switches ON the power transistor within the unit and current flows to the solenoid coil, the injectors open and fuel is injected.

Troubleshooting Hints

Hint 1:

If there is a problem with starting while the engine is warm, perform the combustion test and check for leakage of the injectors.

Hint 2:

If the engine can't be started, and the injectors are not activated during cranking, the cause is probably a malfunction such as described below, not with the injectors.

(1) Malfunction of the circuit for supply of power to the engine control module, or of the ground circuit.
(2) Malfunction of the multi port fuel injection relay.
(3) Malfunction of the crankshaft position sensor and/or the camshaft position sensor.

Hint 3:

If there is a cylinder for which the idling condition does not change when, during idling, the fuel injection of the injectors is cut off in sequence, check that cylinder as described below.

(1) Check the injector and harness.
(2) Check the spark plugs and the high-tension cable.
(3) Check the compression pressure.

Hint 4:

If the injector activation time deviates from the standard value even though the results of the checking of the injector's harness and of the injector itself are normal, the cause may be presumed to be one of the following:

(1) Incomplete combustion within the cylinder. (Malfunction of the spark plugs, the ignition coil, the compression pressure, etc.)
(2) Incomplete close contact of the EGR valve seat.
(3) Increased engine resistance.




Inspection





Using Oscilloscope

(1) Run the engine at idle speed.
(2) Connect the probe to the oscilloscope pick-up point as shown in the circuit diagram, and check the waveform at the drive side of each injector.








Harness Inspection



Actuator Inspection

Checking Operation Sound





Using a sound scope, check the operation sound ("chi-chi-chi") of injectors during idling or during cranking.

Check that as the rotating speed increases, the frequency of the operating sound also increases.

Caution: Note that even if the injector you are checking is not operating, you will hear the operating sound of the other injectors.

Note: If no operating sound is heard from the injector that is being checked, check the injector drive circuit. If there is nothing wrong with the circuit, a defective injector or engine control module is suspected.

Measuring Resistance Between Terminals






(1) Remove the injector connector.
(2) Measure the resistance between the terminals.

Standard value: 13-16 Ohms [at 200 (68°F)]

(3) Install the injector connector.