Questions about automobile ignition coils and high-voltage packages

1. Principle of ignition coil

It is composed of main coil, secondary coil, magnetic core, switching transistor and other auxiliary components. The main coil is charged by the battery, and the secondary coil discharges the spark plug for ignition. , the triode is responsible for switching. The charging time is controlled by the battery voltage and engine speed to ensure consistent energy for each charge. The ignition coil has two types: 3-wire and 4-wire. The 3-wire is for power supply positive, negative, and switch control (ECU command), and the 4-wire has an additional ignition detection Line, capable of detecting whether the spark plug ignites (whether there is discharge current in the secondary coil).

To put it simply, the ignition coil is a transformer, which increases the voltage from tens of volts to tens of thousands of volts, but the voltage input to the primary coil is provided by the electronic ignition. 2. The reasons for the burnout of the ignition coil

The main reason for the burnout of the ignition coil is the aging breakdown of the insulation layer or the damage of the switching transistor. The large gap of the spark plug causes the main coil to have a heavy load and heat, the insulation layer ages quickly, and the spark plug The small gap leads to large secondary coil discharge current, high heat generation, and rapid aging of the insulation layer. The assembled ignition coil may have poor durability of insulation materials, high internal resistance of the coil, high heat generation, and poor quality of the tertiary tube, which will shorten its life.

If it is always burned out and will burn out again shortly after replacement, what are the reasons? Here are some summaries:

1. First look at the problem of the generator. If the power generation is too high, the ignition coil will be easily burned if the load is too heavy. However, if the power generation is really too high, the body electrical appliances, such as light bulbs, etc., will often be damaged; of course, the quality of the accessories does not rule out, so it is best to First measure the power generation. 2. The spark plug gap is too large, adjust the gap or replace the spark plug; 3. The quality of the gasoline 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 repair The factory will use a computer to test the car and clear out the erroneous information. If it still 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 in the secondary; 9. The primary current of the ignition controller is too high, causing the ignition coil to overheat; 10. Exposed to high temperature and high-voltage waves. The problem is that the problem is not working well; 11. There is a small chance that the problem is with the coil itself. You can try another brand; 12. The ignition integrated block is not working well;

The ignition coil itself is a transformer, which is like in household appliances. Like the transformer, when the voltage changes within the specified range, the transformer will not burn. Usually the burnt transformer occurs when the transformer is overloaded. Therefore, when solving this problem, we must try to find out what causes the load. Caused by excessive weight or aging components. 3. Detection method

If the crankshaft position sensor (CKP) and camshaft position sensor (CMP) detect normally, but there is no high-voltage fire, it is usually caused by an open circuit in the power wire of the ignition coil assembly.

(1) Test with a high-impedance multimeter and a light-emitting diode: For models without a distributor for ignition, first unplug the 4-channel ignition coil primary winding plug, and use a high-impedance multimeter to test holes 3 to 4. The voltage should not be less than 11 V. Then connect the LEDs to holes 1, 4 and 3, 4 respectively. If the LED does not flash when the engine is started, it means there is no low-voltage signal, and the low-voltage circuit should be checked. The failure of the power transistor will affect the ignition control signal. The power transistor is the ignition control signal amplifier. Turn off the ignition switch, connect the light-emitting diode between the positive electrode of the battery and the power transistor terminal a, start the engine, and let it run for 10 seconds. If the light-emitting diode does not light up, The power transistor should be replaced.

(2) Resistance value test: The resistance value of the ignition coil is directly related to the quality of ignition performance. If there is no fire or weak spark, the resistance value of the primary winding and secondary winding should be checked. Unplug the high-voltage wires of each cylinder respectively, and measure the resistance values ??between cylinders 1 and 4 and between cylinders 3 and 4 at 20°C. If the resistance value is within the range specified by the manufacturer, it means it is normal; if the resistance value is too low, it means an internal short circuit; if the resistance value is too high, it means an internal open circuit. If the measured value does not match the manufacturer's specifications, it must be replaced.

(3) The main characteristic when the ignition coil is about to be damaged is that the ignition coil is hot and hot to the touch.

(4) Traditional car inspections for ignition coil faults mainly focus on high-voltage flashover. Under the premise that the low-voltage circuit is normal and there is no fault in the ignition coil, there should be strong blue sparks during flashover. The ignition coil of electronic fuel injection mainly measures the impedance of the primary and secondary windings and uses light-emitting diodes to measure circuit continuity.

(5) If it is found that the spark plug of a certain cylinder has no fire or is not working properly, you can unplug the high-voltage branch line of the cylinder, connect a new spark plug, and spark the spark plug 8mm away from the cylinder body. If it is normal, , indicating that the fault is in the original spark plug.

If there is suddenly no fire or weak sparks while driving, you can use an infrared thermometer or hand touch to determine whether there is an internal short circuit or open circuit failure in the ignition coil or ignition module. When judging a fault, you can also restart it. Regardless of whether it can be started, you can measure the temperature of the ignition coil shell to make a judgment.

① Ignition coil overheating: The surface temperature of the ignition coil is greater than 95°C, indicating an internal short circuit of the ignition coil and must be replaced.

② Ignition coil is too cold: When starting, the surface temperature of the ignition coil is equal to the ambient temperature, indicating that the ignition coil is internally broken and must be replaced.

③ Ignition module overheating: If the temperature of the ignition module is higher than 100°C, it means there is a short circuit inside the ignition module and must be replaced.

④The ignition module is too cold: When starting, the ignition module and the ambient temperature are equal, indicating that the ignition module has an internal circuit break and must be replaced.