WS1 Petrol Fuel Injector Testing

WS1   Petrol Fuel Injector Testing

Make: Toyota Model: 4-AFE Year:

Warning, be careful of diesel common rail injectors. They can have very high voltage; do not touch the electrical connectors. This worksheet is only for petrol engines that have up to 15 volts at the injectors.

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 

Comments:
The fuel injectors are working ok

2.        Check voltage to the injectors when idling or Key On. This makes sure you have battery voltage to the injectors so they can work.

Record battery voltage: 12.86v

Record voltage at each injector you can get to by back probing. Be careful to not puncture or damage wiring.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
13.09v	13.21v	13.35v	13.33v			Volts

3.        With engine idling, watch injector firing by using an LED tester or test light (with normal incandescent bulb). Hook up test light and connect tip to pin that has back probed connector to injector -. As the injector is grounded by the ECM to fire, the test light should also be grounded to fire, and will flash.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #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.

        

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
4.9%	4.9%	4.9%	4.9%			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.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
30%	31%	32%	31%			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:

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
7Hz	7Hz	7hz	7Hz			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 your highest reading in the boxes below: Take the readings at the same RPM as you used in question 5.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
30Hz	30Hz	29Hz	30Hz			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


#1 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#1 cyl revved : (30% X 100) / 30Hz = 100 ms
#2 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#2 cyl revved : (31% X 100) / 30Hz = 103 ms
#3 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#3 cyl revved : (32% X 100) / 29Hz = 110 ms 
#4 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#4 cyl revved : (31% X 100) / 30Hz = 103 ms

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
70ms	70ms	70ms	70ms			Calculated Time at Idle
Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
100ms	103ms	110ms	103ms			Calculated Time when revved

Give your conclusion on whether this is an acceptable way to test injectors and why?

This is an acceptable way to test the fuel injectors as you do not need an oscilloscope to check the wave patterns you can use this method to calculate how long the injectors are open for and weather this means the fuel injectors are in good condition