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WS1 Petrol Fuel Injector Testing


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? OK Not OK? ..........
Can you get to all the injectors? Yes
Comments: I could hear a small regular sound for all injector
The reason why we test is because we have to make they working propley and if there is a problem with the fuel injectors a lot of things can happen to your car performance like lack of power vechile will lose its performance it will be using a lot of fuel which is waste of fuel you will be using alot of money on petrol if it doesnt get fixed. it will also fail exhaust emissions test and also it will be hard to start if its cold or hot it wont be idling smoothly. it will have poor driveablitily .

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: 14.06v

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
13.05v	14.06v	14.06v	14.06v	non	non	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.

Note: we did not have the LED tester so i assume they were ok 

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
3.9%	3.9%	3.9%	3.9%			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
12.5%	12.6%	9.3%	10.1%			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
15hz	24hz	20hz	21hz			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
108 hz	119 hz	118 hz	125 hz			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

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
26ms	16.25ms	19.5ms	18.75ms			Calculated Time at Idle
Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
11.75ms	10.59ms	7.88ms	8.08ms			Calculated Time when revved

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

Yes this is an acceptable way to test fuel injectors as if you do not have a oscilloscope 

to check the wave patterns you can use this method to calculate how the injectors are open

for and how weather this means the fuel injectors are in good condition or not.

There are a lot of injector testing  way.  This way also good way to test. We can check how much fuel is spraying by duty cycle. If this test result have no problem,  It mean ECU controll the injector properly and injector solenoid work well. 
However, this test can not guarrant  whether injector work properly.  for example, even injector spray pattern is not corn shape, this test can not check it.
we needed to make sure they injectors are working so we can have a reduce exhaust pollution and improve fuel economy ,increase the performance of the engine and reduce the services and repair cost.