What are the symptoms of a bad car ignition coil?
2 Answers
Symptoms of a bad car ignition coil: 1. When idling, the vehicle body shakes noticeably. You can observe the exhaust pipe outlet, where the exhaust gas flow shows obvious intermittency, accompanied by severe exhaust pipe shaking and clearly audible popping sounds; 2. While driving, when the RPM is below 2500, the vehicle body shakes noticeably with poor acceleration, but the shaking disappears when the RPM exceeds 2500; 3. Open the engine hood and observe the running engine – you'll notice significant engine shaking that clearly exceeds normal operational vibration levels, with very large shaking amplitude.
In my years of experience as an automotive repair technician, ignition coil failure is a very common issue. Symptoms include noticeable engine shaking or vibration, especially at idle, because the coil cannot effectively transmit voltage to the spark plug for ignition, resulting in misfires in one or more cylinders. The vehicle may be difficult to start, often requiring multiple attempts, and is prone to stalling while driving. There is a noticeable drop in power during acceleration, with sluggish throttle response, and fuel consumption may increase by 10%-20% because the engine requires more fuel to compensate for combustion imbalance. The check engine light on the dashboard usually illuminates, with diagnostic codes such as P0300 indicating misfires. Long-term neglect can lead to excessive emissions, damage to the catalytic converter, or spark plugs. It is recommended to regularly check the coil's resistance value and replace faulty coils promptly, as the cost is low, preventing more severe mechanical issues.
