Fuel Injectors

OPERATION
- The injector is an injection nozzle with a solenoid valve which injects fuel according to the injection signal coming from the engine control module.
- The injector has a fixed nozzle opening area and the fuel pressure against manifold inside pressure is regulated to a fixed level. Therefore, the volume of fuel injected by the injector is determined by the time during which the needle valve is open, namely, by the time during which the solenoid coil is energized.
- The battery voltage is applied through the MFI relay to this injector. When the engine control module turns on the power transistor in the module, the solenoid coil is energized to open the injector valve, which then injects fuel.

TROUBLESHOOTING HINTS
Hint 1: If the engine is hard to start when hot, check fuel pressure and check the injector for leaks.
Hint 2: If the injector does not operate when the engine that is hard to start is cranked, the following as well as the injector itself may be responsible.
(1) Faulty power supply circuit to the engine control unit, faulty ground circuit
(2) Faulty MFI relay
(3) Faulty crankshaft position sensor, camshaft position sensor
Hint 3: If there is any cylinder whose idle state remains unchanged when the fuel injection of injectors is cut one after another during idling, make following checks about such cylinder.
(1) Injector and harness check
(2) Ignition plug and high tension cable check
(3) Compression pressure check
Hint 4: If the injector harness and individual part checked good but the injector drive time is out of specification, the following troubles are suspected.
(1) Poor combustion in the cylinder (faulty ignition plug, ignition coil, compression pressure, etc.)
(2) Loose EGR valve seating
(3) High engine resistance

INSPECTION





Using Scan Tool

NOTE:
*1: The injector drive time refers to when the supply voltage is 11 V and the cranking speed is less than 250 r/min.
*2: When coolant temperature is lower than 0° C (32° F), injection is made by 6 cylinders simultaneously.
*3: When the vehicle is new [within initial operation of about 500 km (300 miles)], the injector drive time may be about 10% longer.


























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





Measure the power supply voltage of the front bank injector.
- Connector: Disconnected
- Ignition switch: ON
Voltage (V): Battery positive voltage
OK: GO TO STEP 2
NG: Repair the harness. (A B C1 - MFI relay)





Measure the power supply voltage of the rear bank injector.
- Connector: Disconnected
- Ignition switch: ON
Voltage (V): Battery positive voltage
OK: GO TO STEP 3
NG: Repair the harness. (D1 - MFI relay)





Check for an open-circuit, or a short-circuit between the front bank injector and the engine control module.
- Injector connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 4
NG: Repair the harness. (A B C2 - 1 24 10)





Check for an open-circuit, or a short-circuit between the rear bank injector and the engine control module.
- Connector: Disconnected
- Engine control module connector: Disconnected
OK: STOP
NG: Repair the harness. (D2 5 6-9 2 25)

INJECTOR CHECK
Measurement of Resistance between Front Bank Terminals
(1) Remove the injector connector.





(2) Measure the resistance between terminals.

Standard value: 13 - 16 Ohms [at 20°C (68°F)]

(3) Install the injector connector.





Measurement of Resistance between Rear Bank Terminals








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