WS1 Petrol Fuel Injector Testing

1. Listen to the injectors as the engine is idling. Use stethoscope, vacuum line or long screwdriver. Be careful of moving parts. They should sound like a sharp tap, not a dull thud or nothing.

This is a crude test to see if they are being actuated and are opening. Ok

Can you get to all the injectors? Yes


2. Check voltage to the injectors when idling or Key On.
Record battery voltage: 14.40v

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
14.08	14.00	14.10	14.00			Volts

3 With engine idling, watch injector firing by using an LED tester or test light.)

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
Ok	OK	OK	OK			Tick if flashes ok

 4. With engine idling, watch injector firing by using a multi-meter set to read % (duty cycle). Record the readings for each cylinder at idle in the boxes below.

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
96%	95.7 %	95.7 %	094.9 %			Duty cycle %

5. With the multi-meter still set to read % (duty cycle), accelerate the engine with short, fast throttle openings (don't over-rev or damage the engine please), and note in the boxes below the maximum % reading you can get on the multi-meter: note the RPM.

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
77.4 &	082.4 %	076.9 %	080.7 %			Duty cycle %

6. Set the multi-meter to read Hz, and with the engine idling, record the readings for each cylinder in the boxes below:

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
8.64 %	8.495 %	8.687 %	8.201 %			Hz

7 With the multi-meter still set to read Hz, increase the engine RPM (don't damage the engine), and watch how the Hz changes. Record the highest reading in the boxes below: Take the readings at the same RPM as used in Q5.

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
41.76 %	37.33 %	37.70 %	37.91 %			Hz

Using this formula calculate the pulse width of each injector both at idle and when the engine is revved up.

"Pulse width ms = (% Duty cycle/100)/Frequency"

Show your calculations

96% / 100 / 8.64 Hz = 0.11 ms

Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
0.11 ms	0.11 ms	0.10 ms	0.11 ms			Calculated Time at Idle
Cyc #1	Cyc #2	Cyc #3	Cyc #4	Cyc #5	Cyc #6
0.018 ms	0.02 ms	0.02 ms	0.02 ms			Calculated Time when revved