Fuel Injector: Testing and Inspection

FUEL INJECTOR




The injectors inject fuel to cylinders according to the signal, suitable to engine condition, from ECU. The ECU drives the injectors by electric current driving mode.

The basic fuel amount is performed by the mapping value based on the air amount and engine rate, and the fuel amount is corrected in the case of fuel amount correction (Air fuel ratio control signal, fuel evaporative emission gas control, learning increase of the fuel amount, warm-up control, catalytic heating control, fuel amount control in deceleration, idle control, fuel amount increase in full load, fuel increase in acceleration and restarting)

The fuel injection is controlled under unavailable state for safety purpose when engine rpm reaches the appropriate engine speed [On driving: 6300 - 6800 rpm, Engine stop (N-range): 4700 rpm].

Circuit Diagram (Injector):

Harness Connector:

INJECTOR INSPECTION

Injector Inspection Part 1:

Injector Inspection Part 2:

1. USING HI-SCAN (PRO)

NOTE:
- Drive time indicates the injector activation time when the supply voltage is 11 V and the cranking speed is less than 250 rpm.
- When engine coolant temperature is lower than 0 °C (3 °F), the ECU fires all four cylinders simultaneously
- When the vehicle is new (within initial operation of about 500 km [300 miles]), the injector drive time may be about 10% longer

2. USING STETHOSCOPE AND VOLTMETER







1. OPERATION SOUND CHECK
a. Using a stethoscope, check the injectors for a clicking sound at idle. Check that the sound is produced at shorter intervals as the engine speed increases.

CAUTION: Ensure that the sound from an adjacent injector is not being transmitted along the delivery pipe to an inoperative injector.

b. If a stethoscope is not available, check the injector operation with your finger. If no vibration is felt, check the wiring connector, injector or injection signal from the ECU.

2. RESISTANCE MEASUREMENT BETWEEN TERMINALS
a. Disconnect the connector at the injector.
b. Measure the resistance between terminals.

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




c. Re-connect the connector to the injector.

TROUBLESHOOTING HINTS

1. If the engine is hard to start when hot, check for fuel pressure and injector leaks.
2. If the injectors do not operate when the engine is cranked, then check the followings:
- Defective power supply circuit to the ECU, faulty ground circuit
- Defective control relay
- Defective Crankshaft Position (CKP) Sensor or Camshaft Position (TDC) Sensor

3. If there is any cylinder whose idle state remains unchanged when the fuel injectors are cut one after another during Idling, check for the following items about that a cylinder.
- Injector and harness
- Ignition plug and high tension cable
- Compression pressure

4. If the injection system is OK but the injector drive time is out of specification, check for the following items.
- Poor combustion in the cylinder (faulty ignition plug, ignition coil, compression pressure, etc.)
- Loose EGR valve seating

Harness Inspection Procedures: