Fiat 500 not running properly with a miss after new plugs and coil pack installation on Fiat 500

Some Fiat 500 owners report experiencing performance issues, such as engine misfires, even after replacing spark plugs and the coil pack. These problems may arise from underlying coil pack issues that persist despite new installations. Additionally, owners should check the condition of the spark plugs to ensure they are correctly installed and functioning, as new plugs can sometimes temporarily mask ignition coil problems. Misfire diagnosis is crucial, as the issue could stem from other components like the fuel system or the engine control modules. Some owners notice the check engine light activating, which often indicates bad coil packs detectable by the engine's computer. If issues persist, it is advisable to consult a professional mechanic for a thorough diagnosis. Symptoms of idle misfire, such as excessive vibrations felt through the seat and visible vibrations in components, may also indicate the need for further investigation.