WS1 Petrol Fuel Injector Testing

WS1 Petrol Fuel Injector Testing

Make TOYOTA Model 4A-FE 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 ....O.... Not OK ..........

Can you get to all the injectors? Yes ....O.... No .........

Comments: All injectors properly work and have good conditions.

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: 14.16 v

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
14.11 v	14.12 v	14.11 v	14.11 v				Volts

3.With engine idling, watch injector firing by using an LED tester or test lightECM 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
√	√	√	√			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
1.1%	1.0%	0.9%	0.9%				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
5.1%	9.6%	6.3%	7.9%			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
15Hz	15Hz	15Hz	15Hz			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 : (1.1% / 100) / 0.007kHz = 1.57 ms
#1 cyl revved : (5.1% / 100) / 0.015kHz = 3.4 ms
#2 cyl idle : (1.0% / 100) / 0.007kHz = 1.43 ms
#2 cyl revved : (9.6% / 100) / 15Hz = 6.4 ms
#3 cyl idle : (0.9% / 100) / 0.007kHz = 1.29 ms
#3 cyl revved : (6.3% / 100) / 0.015kHz = 4.2 ms
#4 cyl idle : (0.9% / 100) / 0.007kHz = 1.29 ms
#4 cyl revved : (7.9% / 100) / 0.015kHz = 5.27 ms

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
1.57 ms	1.43 ms	1.29 ms	1.29 ms			Calculated Time at Idle
Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
3.4 ms	6.4 ms	4.2 ms	5.27 ms			Calculated Time when revved

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

From the petrol fuel injector testing, when the engine is idling, the duty cycle and frequency values are lower than high rpm condition. As a result, the injectors shortly open when the engine run with idling, however the injectors open longer with more fuel injection when the engine runs with higher rpm.