WS1 PETROL FUEL INJECTOR TESTING

This experiment was held on the Nissan Pulsar year  1998 

At first stage I used stethoscope to listen to the sound injector produce. Once the engine was idling it was easier to recognise tapping sound from each injector. It shows that all of them are working.

Measuring battery voltage I found that battery was not charged properly. As a result, voltage at each injector was lower than it should have been. 

Cyl#1	Cyl#2	Cyl#3	Cyl#4
12.1V	12.08V	12.10V	12.09V

However, voltage drop between battery positive terminal and injectors has shown relatively good connection. Volt drop is around 0.09 V ( Vb-Vinj=12.19-12.10=0.09 V ). It could be better if the battery posts were cleaned from corrosion. Engine start was not affected at this point.

LED tester I built was used for the next test. At each injectors pin I could read pulsing signal from the tester. The higher engine revs the higher frequency of these pulses. 

 Reading the duty cycle at idle engine speed I got these results:

Cyl#1	Cyl#2	Cyl#3	Cyl#4
99.9%	99.8%	99.8%	99.8%

Reading the duty cycle at short acceleration I got these results:

Cyl#1	Cyl#2	Cyl#3	Cyl#4
91.8%	92%	92.1%	91.2%

Frequency measurements brought me these results:

Cyl#1	Cyl#2	Cyl#3	Cyl#4
10.4 Hz	10.8 Hz	10.2 Hz	10.9 Hz

Frequency measurements with the engine RPM increased:

Cyl#1	Cyl#2	Cyl#3	Cyl#4
22.5 Hz	24 Hz	25 Hz	19.2 Hz

With formula “Pulse width in ms= % Duty cycle*100/Frequency”

I got this table of results:

Cyl#1	Cyl#2	Cyl#3	Cyl#4
9.6ms	9.2 ms	9.7 ms	9.2 ms
4.0 ms	3.8 ms	3.6 ms	4.7 ms

The outcome from this experiment is obvious.  The higher engine revs the longer injectors are opened. This is the way how to supply engine cylinders with increased amount of fuel.

However, another conclusion can be made on the basis of this experiment. All these methods of testing above are suitable only for express analysis to make sure those injectors work. Detailed diagnostics must be completed by using oscilloscope.