Wiring up ignition systems

Wire up an ignition module and function generator as a trigger, coil and a spark plug.








Ignition system with distributor. It needs to be rotated fast to generate a spark.












Wasted coil set up.











Coil on a plug set up.








Building a simplified ignition module.
In this circuit we used a transistor and function generator to trigger coil primary circuit so it can induce high voltage in the secondary. Small problem we had with finding transistor data sheet as there are so many manufactures and they all slightly different.

Ignition module usually use transistors to trigger ignition coil by braking power supply to it, also can be used multiple transistors called Darlington pair, the trigger could be distributor, crank and cam sensors which tells when to ignite a spark plug.

All experiment we performed shows that the ignition system take a big step in progress from Kettering ignition system to coil on a plug, but they all work on the same principles by braking the power supply to primary coil so it will induce high voltage in the secondary for spark plug to fire. On elder vehicle system called points ignition been used, it had a fixed dwell and firing angle, but could be advanced and retarded timing with vacuum or mechanical mechanisms. Late model systems can vary dwell and firing time and adjust advanced or retarded ignition with the help of ECU and the sensors.

Testing ignition coil

Testing primary and secondary windings of the coil.











Wasted spark coil pack.
















Testing ballast resistor.
Ballast resistor number: 13R3
Specifications: 1.5-1.7 ohms
Measured resistance: 1.6 ohms
This ballast resistor in manufactures specs and still can be used.

Measuring current draw and voltage drop of standard single tower coil.
Calculated voltage drop and measured voltage drop are equal as the Ohms Law says Volts=Amps*Resistance.

Fuel injector testing

Fuel injector is a actuator which supply engine with fuel (petrol or gasoline) to run. As its an actuator it has and off and on time, which determined by ECU.













Here is an injector resistance test.






Here is and injector click test, injector 2 and 4 were seized up untill i hit them on a table they didn't wanna work.

When injector not working it can make miss fire, poor performance and erratic idling of the engine.

Test bench cleaning: in this procedure injectors can be cleaned and inspected in the same time.
During the test we can see spray pattern, delivery volume and injector leakage.
When removing injectors from the engine, battery must be disconnected, ignition off and avoid flames and sparks around fuel.

During this test all four injectors has had a good spray pattern, had no leakage under pressure and after been tested and delivered around 180 cc. per minute, so they still usable and none of they require attention.

Optical sensor

The one i like as it installed on my Nissan Skyline. As we didn't have one at Unitec i have to bring my own to test.

Inside this sensor is a infra red diode and photo electric cell with interrupter plate with a lot of open windows for the sensor to know where top dead center and number 2,3 and 4 cylinders.
Here is oscilloscope reading which shows that a negative trigger switch. On a picture we can see supply voltage of 5 volts main line and when interrupter ring rotates and blocks the LED we can see voltage goes to ground to 0 volts. Its isn't a perfect pattern, but its visible that sensor works and give reading. And it basically work as a Kettering ignition system by braking the power supply to coil to induce high voltage for spark plug to fire. This is the most correct speed sensor compare to hall-effect and magnetic pick up ones, as its got a scale of 360 degrees. This is the most advanced and also most expensive to build so progress decide to take advantage on cheep magnetic pick up sensors which can be found in late model cars ABS, TRS and ignition systems this days. No one wanna pay extra for quality and reliability.

Hall-Effect sensor

Here is a Hall-Effect sensor explanation, all in one picture!

It will also come to such point when dwell time will be so short so the coil couldn't recharge and the spark would be weak, loss of power and torque and that why all our car has got a red line on our rev counter =)

Speed or Position sensor

Visual inspection ok. Mesured resistance is in manufactures spesification.


Adjusting gap with filler gauge.










Here is a graph for G and NE pick ups, its a top dead center (cylinder #1) and cylinder 2, 3 and 4. So the big wave is a number 1 and small three are cylinder 2, 3 and 4. This wave form repeats shape of the teeth.







Marked with A arrow is peak voltage output of the sensor.
Marked with B arrow is a time in milliseconds between each teeth approach the sensor.

Knock Sensor

In all cars the best combustion and more performance can be achieved with the most possible advanced ignition before it starts to detonate. So this sensor controls knocking or detonation in the engine and with it help ECU can advance or retard timing. Inside this sensor is piezoelectric crystals which produce voltage when vibrating. So when vibration detected this sensor sends a signal to ECU so it can retard timing. It set up to a certain frequency so it wont read injectors and mechanical noises of the working engine.


Here is an oscilloscope reading of knock sensor!











So this shows that knock sensor can produce different voltage with different frequency.