Spark plugs are essential to a vehicle’s ignition system and ensure it runs smoothly and efficiently. Unfortunately, spark plugs break down or malfunction regularly, so keep an eye out for these common signs of faulty spark plugs in your car.
Struggle To Start
One of the clearest signs that your vehicle’s spark plugs are malfunctioning is that it struggles to start or takes a while to turn on. After all, the primary function of spark plugs is igniting the fuel and air mixture that puts the pistons in motion for your car to run.
So for cars that misfire or struggle to turn over, spark plugs are a common culprit. But many components are involved in your engine’s ignition system, so you don’t want to assume it’s the spark plugs and immediately replace them before having a professional examine them.
Rough Idle
Have you ever been sitting at a traffic light or stop sign, and your car starts idling roughly or vibrating? A rough idle can come from many causes, but one of the most common reasons is that the vehicle’s spark plugs are damaged or failing.
When a vehicle’s spark plugs or ignition system malfunction, that can manifest in a vibration or jittery sound while the vehicle is idling. This vibration comes from a cylinder misfiring, which means problems within the ignition system. Typically, spark plugs are the roots of these issues.
Sluggish Acceleration
Another common sign of faulty spark plugs in a car is a reduction in the vehicle’s acceleration. The ignition system is integral to a vehicle’s acceleration capabilities. So if the spark plugs or other components malfunction, it will affect the car’s performance.
That’s not the only possible reason for the lack of acceleration in a car—it could also be the fuel filters, the fuel injector, the oxygen sensor, or several other things. If your car seems more sluggish than it used to, have a professional look at the spark plugs and ignition system.
Poor Fuel Economy
Along with starting and accelerating the car, spark plugs ensure the vehicle burns fuel efficiently. If there’s a problem with the spark plugs, such as the electrodes being too close or far apart, it can result in your vehicle burning more fuel than usual.
Pro-Tip: You can manually track your car’s fuel consumption by dividing the number of miles you drive by the number of gallons you put in your tank for a fill-by-fill fuel economy reading.
The difference in fuel consumption between capable and malfunctioning spark plugs is subtle, so it’s difficult for a casual driver to notice. But a loss in fuel economy typically occurs along with the other symptoms we’ve mentioned, such as a rough start and poor acceleration. Therefore, if it seems like you’re filling up your tank more often while the car struggles to turn over, the culprit is likely the spark plugs.
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