Principle of the ignition coil

It is composed of the main coil, a secondary coil, a magnetic core, a switching transistor and other auxiliary components. The main coil is charged by a battery, and the secondary coil is discharged by a spark plug to ignite, and the triode is responsible for switching. The charging time is controlled by the battery voltage and the engine speed to ensure that the energy is consistent each time. The ignition coil has two types: 3-wire and 4-wire. The 3-wire is the power supply positive, negative, switch control (ECU command), and the 4-wire has one more ignition detection. Wire can detect whether the spark plug is ignited (whether there is discharge current in the secondary coil).

To put it simply, the ignition coil is a transformer, which increases the voltage of tens of volts to tens of thousands of volts, but the voltage input to the primary coil is provided by an electronic igniter.

The reason why the ignition coil burns out

Ignition coil burnout is mainly caused by the ageing and breakdown of the insulation layer or the damage of the switching transistor. The large gap between the spark plugs will cause the main coil to load, heat, and age quickly. The small gap between the spark plugs will cause the secondary coil to discharge current, heat, and insulation. Fast, the assembled car coil may have a shorter lifespan, such as poor insulation material durability, the large internal resistance of the coil, high heat generation, and low quality of the tertiary tube.

If it is always burned out, it will burn out soon after replacement. What is the reason? Here are some of them:

1. First look at the problem of the generator. If the power generation is too high, the car coil will burn out if the load is too heavy, but if the power generation is really too high, then the body electrical appliances, such as light bulbs, will often be damaged; of course, The quality of the accessories is not ruled out, so it is best to measure the power generation first.

2. The spark plug gap is too large, adjust the gap or replace the spark plug;

3. The gasoline quality is not good, try changing to a higher-grade gasoline;

4. The cylinder compression ratio is wrong, adjust the compression ratio;

5. If there is a program failure on the computer board, you can go to the repair shop to test the car with a computer and clear the error message. If it doesn't work, there may be a problem with your car's transmission.

6. The power supply voltage is unstable;

7. The resistance of the high-voltage line is abnormal, replace the high-voltage line;

8. There is a short circuit phenomenon in the secondary;

9. The primary current of the ignition controller is too high, causing the ignition coil to overheat;

10. Problems with high temperature and high-pressure wave work well;

11. It is very unlikely that the coil itself is a problem, you can try another brand;

12. The integrated block of the igniter does not work well;

The car coil itself is a transformer, which is like a transformer in a household appliance. When the voltage changes within a specified range, the transformer will not be burned. Usually, the burning of the transformer occurs when the transformer is overloaded. When solving this problem, we must try to find out the cause of the excessive load or the aging of the components.

If there is no fire or weak sparks that suddenly occur during driving, an infrared thermometer or hand touch can be used to determine whether the car coil or the ignition module has an internal short circuit or open circuit fault. When the fault is judged, it can also be restarted. 

Regardless of whether it can be started, it can be judged by measuring the temperature of the ignition coil casing:

①The ignition coil is overheated: the surface temperature of the ignition coil is greater than 95℃, indicating that the ignition coil is short-circuited and must be replaced.

②The ignition coil is too cold: the surface temperature of the ignition coil is equal to the ambient temperature when starting, indicating that the ignition coil is open and must be replaced.

③The ignition module is overheated: the temperature of the ignition module is higher than 100°C, indicating that the ignition module is short-circuited and must be replaced.

④The ignition module is too cold: the ignition module and the ambient temperature are equal when starting, indicating that the ignition module is internally open and must be replaced.