What are the precursors of a damaged car ignition coil?

[Willis]

Before the ignition coil is damaged, the vehicle may suddenly experience abnormal shaking while driving, accompanied by a noticeable loss of power. The following are specific descriptions of the types of ignition coil failures: Ignition coil winding short circuit: Unable to convert the low voltage from the battery to high voltage, resulting in insufficient ignition energy, and the spark plug is prone to carbon deposit contamination. Ignition coil surface discharge: Discharge and sparking on the outer surface of the ignition coil, mainly due to dirt and severe moisture on its surface. Ignition coil insulation aging: Often caused by high temperatures after the engine is hot or frequent ignition under heavy load, leading to a rapid rise in the ignition coil temperature and subsequent aging.

[GriffinLynn]

I can totally relate to this issue from my last experience. While driving, I could clearly feel the engine shaking violently, like a phone stuck in vibration mode. The acceleration was particularly weak, and even flooring the gas pedal felt sluggish when going uphill. One cold morning, the car failed to start three times in a row, and suddenly the yellow engine light on the dashboard came on. The most annoying part was the fuel consumption skyrocketing—normally a full tank would last 500 km, but back then the low fuel warning came on at just 400 km. Later, I found out it was due to failing ignition coils. The mechanic said these symptoms were classic signs of a dying ignition coil, and catching it early could save a lot of money.

[DeEvelyn]

From my decade-long experience in auto repair, there are several clear signs before an ignition coil fails: First, the engine idles roughly with noticeable shaking, accompanied by intermittent backfiring sounds upon close listening. Then, the jerking sensation during acceleration becomes increasingly severe, especially in the 30-40 mph range. Some vehicles may also emit black smoke from the exhaust with particularly pungent fumes. The most troublesome symptom is engine misfiring—you can feel excessive vibration at a specific spot when touching the hood. This issue requires immediate attention, as delay could lead to collateral damage to the catalytic converter, potentially doubling repair costs.

[DelRachel]

I learned this lesson the hard way with my old Jetta. At first, it became difficult to start – once after shopping at the supermarket, it took me five attempts to get it going. Then the tachometer needle started jumping erratically, and the engine would sputter whenever I went over speed bumps. Later I realized these were all signs of aging ignition coils. Now when I do my own inspections, I pay special attention to these points: checking the ignition coils for any visible leakage or cracks, measuring if the resistance deviates more than 20% from standard values, and testing if the spark plugs produce stable sparks. These little tricks can help you avoid being stranded on the road.

[MiaLee]

Last time I went on a self-driving trip to Inner Mongolia, I encountered this annoying issue. On the first night when I parked the car, I smelled a burnt wire odor but didn't pay much attention. The next day while driving on the highway, I noticed the throttle response was extremely sluggish—the RPM surged when overtaking, but the speed wouldn't increase. The scariest part was when the engine suddenly misfired on the Gobi Desert, making a hiccup-like stuttering sound. During the repair, the mechanic showed me that the ignition coil casing had even developed cracks. He said the leakage current caused abnormal continuous sparking in the spark plugs, and prolonged operation in this condition could wear out the piston rings. Fixing it wouldn’t be as simple as just replacing a coil.