How does a spark plug work?
The spark plug
creates an artificial bolt of lightning (literally!) within the combustion chamber, the cylinder head of the engine. The electrical energy, or voltage, it transmits is extremely high in order to create a spark and to “light the fire” within the controlled chaos of the combustion chamber. Here, the voltage generated by the spark plug can be anywhere from 20,000 to more than 100,000 volts!
Without spark, there would be no way for fuel to ignite in the combustion chamber. Spark plugs are specifically designed to transmit the electrical signal sent by the ignition coil
at a predetermined time and ignite the fuel inside the combustion chamber at the proper moment. Consequently, each vehicle requires a unique spark plug made from specific materials and with a designated spark plug gap. When do I need to replace spark plugs?
A good spark plug will help burn fuel efficiently while a “bad” spark plug can cause the motor not to start at all.
Most vehicles sold in the US require that spark plugs are replaced every 50,000 to 100,000 miles. However, newer manufactured vehicles have advanced ignition systems that claim to have lifetime warranties. Regardless of the warranty, or claims made, there are times when a spark plug wears out, or shows signs of failing. Common signs include slow acceleration, poor fuel economy, engine misfiring, and difficulty starting the vehicle. How do I know when to change the ignition coil?
Check your owner’s manual to find out when you should replace the ignition coils, but usually you only need to replace them if they go bad.
A bad ignition coil sometimes causes a vehicle to not start at all. Additionally, a vehicle will run poorly, shaky when idling, or slow to respond when trying to accelerate, and stops erratically during the drive. The vehicle will also backfire when the exhaust system emits unused fuel. The way to detect this is when the exhaust emits a black smoke and smells of gasoline. Some other common signs include the Check Engine Light coming on, engine misfiring, a reduction in power, and the car not starting.
Because of how similar the issues can be when a spark plug or ignition coil goes bad, the general rule of thumb is to replace your spark plugs every 50,000 to 100,000 miles, and if you are replacing an ignition coil, to replace that cylinder’s spark plug as well.