Injectors

Injector testing
NOTE: Common values
            with resistor            1.5-3 ohms
            (or current control built into the ECU)
            Without resistor       14.0-17.0 ohms


Checking injectors off a vehicle

Injector number
1
2
3
4
Manufacture specification ohms   
13.5
13.8
13.8
13.8
Winding resistance ohms
14.2
14.2
14.2
14.2
Earth leakage test
o/l
o/l
o/l
o/l


An injector is a solenoid in which when a current is induced into the windings inside the injector it creates a magnetic field and because the injector needle is surrounded by these windings it pulls the needle open to allow the fuel to pass through.
To test the winding resistance on an injector i measured the resistance from one pin to the other pin on the injector with a multimeter with the red prong on one pin the black one on the other.The resistance in the windings is very important because if it to be wrong it would effect the operation of the injector e.g. if the resistance were to high it would take more voltage to open and because only 12v is supplied the injector will not open fully causing less fuel to be injected.
The earth leakage test is testing if the windings are in contact with the body of the injector. To test this i used a multimeter on the resistance function and placed one probe on one of the pins and the other probe on the body and i got O/L for all 4 injectors which means the winding's are not connected to the body of the injector for all of them. If i had got a reading it would mean the injector has a short circuit.

Now i wired up each injector to a 5v supply and an earth to see if i could hear a "click". The click is the needle pulling up due to the magnetic field created as a voltage is supplied, all injectors clicked.
If an injector was not firing it could be that the injector is not receiving full available voltage.

Test bench cleaning
when removing injectors from the engine take care to relieve the pressure in the fuel system
 What i was testing: Injector spray pattern, Offset spray pattern, Delivery volume and injector leakage (Dribble) all 4 injector were good and had no dribble.

Test results
Injector number
1
2
3
4
Spray pattern
Good
Good
Good
Good
Flow rate
Good
Good
Good
Good
Injector leakage
Good
Good
Good
Good

No injectors required attention




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