How to Determine the Quality of an Ignition Coil?
2 Answers
Methods to determine the quality of an ignition coil are: 1. Feel the temperature of the ignition coil shell by hand; if it feels warm, it is normal, but if it feels scalding hot, it indicates an inter-turn short circuit fault in the ignition coil. 2. Measure the resistance of the primary and secondary windings with a multimeter. If the resistance is infinite, it indicates an open circuit fault in the winding. If the resistance is too high or too low, it suggests poor contact or an inter-turn short circuit in the winding. Symptoms of a faulty ignition coil include: 1. Individual cylinders not working due to no spark, resulting in rough idling and lack of power when accelerating. 2. Ignition coil leakage. 3. Occasional power interruption during acceleration. 4. Failure to start the car due to the ignition coil not firing.
I've just dealt with an ignition coil issue, and it's something that requires careful attention. If the car engine starts shaking violently, especially during idle or acceleration, the first thing I suspect is the ignition coil. I personally perform a spark test: remove a spark plug wire, hold the top of the spark plug close to a metal part, start the engine and observe the spark—if there's no spark or it's too weak, it likely indicates a faulty ignition coil. Using a multimeter is also reliable: the primary coil resistance should normally be between 0.5 to 2 ohms, and the secondary coil between 5000 to 15000 ohms; if the values are off, it's time for a replacement. A swap test is even more straightforward: move the suspected faulty ignition coil to another good cylinder, and if the problem follows, that pretty much confirms it. Additionally, when the engine warning light comes on, scan the OBD codes—codes like P0301 indicate a misfire in a specific cylinder. Don't overlook a visual inspection: cracks or a burnt smell are bad signs. Failing to repair it promptly could damage the catalytic converter and increase fuel consumption, so I always check it during every maintenance session.
