What cause ignition coil to burn out? If ignition coil burns out all the time, it will burn out again soon after replacing ignition coil,  why? How to detect ignition coil? This article will revolve around these questions.

1. Detection method

The crankshaft position sensor (CKP) and camshaft position sensor (CMP) are tested normally, but there is no high voltage spark, and usually power leads of the ignition coil assembly are broken.

(1) Test with high-impedance multimeter and light-emitting diode: For vehicles without distributor, first unplug the primary winding plug of 4-channel ignition coil and test 3 ~ 4 connector pin with high-impedance multimeter with voltage no less than 11 V. Then connect the light-emitting diode with connector pin 1, 4 and 3, 4 respectively. If the light-emitting diode does not shine when the engine is started, it means there is no low-voltage signal. Check the low-voltage circuit. The fault of the power transistor will affect the ignition control signal. The power transistor is the ignition control signal amplifier. Disconnect the ignition switch and connect the light-emitting diode between the battery positive pole and the power transistor terminal to start the engine and make it run for 10s, If the light-emitting diode does not shine, replace the power transistor. 

(2) Resistance value test: The resistance value of the ignition coil is directly related to the ignition performance. If there is no spark or weak spark, the resistance value of the primary winding and the secondary winding should be checked, and the high-voltage lead of each cylinder should be pulled out respectively. The resistance value between 1 and 4 cylinders and between 3 and 4 cylinders should be measured at 20℃. If the resistance value is normal within the scope specified by the manufacturer, if the resistance value is too low, it indicates an internal short circuit; If the resistance is too high, the internal circuit is open circuit. If the measured value does not conform to the manufacturer's regulations, it must be replaced.

(3) When ignition coil is about to be damaged, the main characteristic is that the ignition coil is hot.

(4) The fault of ignition coil of a classical car is mainly judged from the jump spark of high voltage. Under the premise of the normal low-voltage circuit, if the ignition coil has no fault, it should be a strong blue spark at jump spark. 

(5) If the spark plug of a cylinder is not working well or does not fire, the high tension lead from the cylinder can be pulled out, and replace a new spark plug. The spark of spark plug can jump 8mm between the cylinder block and outside the cylinder. If it is normal, the fault is in the original spark plug.

If there is no spark or weak spark during driving, infrared thermometer or touch the ignition coil with your hand can bedetermined whether the ignition coil or ignition module has internal short circuit or open circuit fault. When fault is judged, it can also be restarted. Whether it can be started or not, it can be judged by measuring the temperature of the ignition coil housing.

(1) Ignition coil overheating: the surface temperature of the ignition coil is more than 95℃, indicating that the ignition coil internal short circuit, must be replaced.

(2) Ignition coil undercooling: The surface temperature of the ignition coil is equal to the ambient temperature when starting, indicating that the internal circuit of the ignition coil is open circuit and should be replaced.

(3) Ignition module overheating: Ignition module temperature is higher than 100℃, indicating that the ignition module internal short circuit, must be replaced.

(4) Ignition module undercooling: The ignition module and the environment temperature are equal when starting, indicating that the ignition module internal circuit is open circuit, means it should be replaced.