Q: What's the importance of spark plugs on 2000 Chevy impala

The function of spark plugs is to ignite the air/fuel mixture in each cylinder. The engine needs spark, air, and fuel to run. In the simplest terms, what’s happening inside your engine is small explosions in each cylinder. For that explosion to happen, the air and fuel mixture needs a spark. As the name indicates, the spark plug provides that spark for the explosion to happen. Worn or fouled spark plugs can cause poor performance, low power, hard starting, rough running, and poor gas mileage. Electrical power for the entire vehicle, including spark plugs, generally comes from the alternator. The battery is there primarily to start the vehicle. Once it’s running, electrical power for engine controls - including spar plugs, ;lights, heat and a/c, radio, etc, is provided by the alternator.