5 Signs of Bad Spark Plugs

5 Signs You Need New Spark Plugs 1. Engine Misfires A misfiring engine is a big sign that one or more of your spark plugs are not firing properly. A misfire may sound like a sputtering sound or feel like a sudden loss of power or violent shaking. Consistent misfiring may result in poor vehicle performance, low fuel economy, higher exhaust emissions, rough idling, and a damaged catalytic converter. 2. Poor Gas Mileage When spark plugs are working correctly, they burn fuel efficiently in your engine. If you notice you are getting less mileage per tank of gas, deteriorated spark plugs may be the cause. As spark plugs age, the space between the plug electrodes can expand or decrease. This causes the spark plugs to not fire or fire erratically, wasting fuel and increasing emissions. 3. Trouble Starting Dirty, damaged or worn-out spark plugs make it difficult to deliver the spark needed to start your vehicle’s engine, especially in cold weather. This may result in a jerky start or the vehicle cranking for a long time before starting. If this continues over time, it can damage your engine and starter and drain your car battery. 4. Slow Acceleration If you press down on your gas pedal and the vehicle doesn’t react as quickly as usual, your spark plugs could be causing a delayed response. However, this could also be caused by other factors, such as dirty fuel injectors, faulty oxygen sensors or a bad fuel pump. So make sure to get your vehicle diagnosed by a qualified technician before paying for new spark plugs. 5. Rough Idling Keep your ears open for any rattling, pinging or knocking sounds—these are another bad spark plug symptom. If your vehicle’s engine is making any unusual sounds or vibrations while idling, your vehicle’s spark plugs may not be functioning properly to keep the engine running smooth.