WS1 Petrol Fuel injector Testing

Petrol Fuel Injector Testing


1. Listen to the injectors as the engine is idling :
I had used along screwdriver all injectors sound like sharp tap. That of all injectors OK


2 Check voltage to the injectors when idling or Key On. This make sure you have battery voltage to the injectors so they can work .
Record battery voltage: 14.40 V
Record voltage at each injector:

CY # 2	CY # 1	CY # 3	CY # 4
14.0	14.08	14.10	14.08	Volts

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

CY # 2	CY # 1	CY # 3	CY # 4
ok	ok	ok	ok	If flashes

With engine Idling watch injector firing by using multi- meter set to read % (duty cycle). Record the reading for each cylinder at idle in the boxes.

CY # 1	CY # 2	CY # 3	CY # 4
96.0%	95.9%	95.7%	94.9%	Duty cycle %

4. with the multi- meter still set read % (duty cycle), accelerate the engine with short, fast throttle opening , and note in the boxes below the maximum % reading. 

CY # 1	CY # 2	CY # 3	CY # 4
77.4%	82.4%	76.9%	80.7%	Duty Cycle %

6. set multi - meter to read Hz, and with the engine idling, record the reading for each cylinder:

CY # 1	CY # 2	CY # 3	CY # 4
8.41	8.49	8.86	8.20	Hz

7. With the multi - meter still set to read Hz. Increase the engine RPM, and watch how the Hz changes.
Record the reading in the boxes.

CY # 1	CY # 2	CY # 3	CY # 4
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"
calculation: 96% /100 / 8.41 Hz =0.114 ms . this calculation an idling.

CY # 1	CY # 2	CY # 3	CY # 4
0.11 ms	0.112 ms	0.110 ms	0.108 ms	Calculated Time at Idle
CY # 1	CY # 2	CY # 3	CY # 4
0.018 ms	0.0220 ms	0.020 ms	0.021 ms	Calculated Time when revved

Note: injector pulse width ( range of 0 - 25 ms) this is amount of time that injector are open, not duty cycle , the duty cycle is regularly as the ratio of amount of time a signal (active) to the amount of time available for the signal to active.