Spark plugs may be small in size, but they have the important job of igniting fuel in the combustion chamber of a vehicle so the engine can run. When your spark plugs begin to fail, you will likely notice a marked difference in how your vehicle operates. Knowing the signs of bad spark plugs will give you the opportunity to fix the problem before any damage can occur to your vehicle. Some of the most common issues with bad spark plugs include:

Misfiring Engine

When your car's engine misfires, you will likely notice it. An engine misfire usually feels like the engine stumbles or hesitates before regaining its normal performance. These engine misfires typically occur because the spark plugs are not able to provide the energy needed to ignite the fuel in the combustion chamber, so the engine is not getting the power it needs to operate properly. In many cases, engine misfires are due to bad spark plugs, but any time your engine stumbles or hesitates while in motion you should have your car looked at by a mechanic.

Bad Fuel Economy

If you notice that you're stopping at the gas station more often to fuel your vehicle, it may be because your spark plugs are failing. When spark plugs begin to fail, there can be incomplete fuel combustion, which increases the amount of emissions a car creates, thus effecting the exhaust system. Replacing the spark plugs is usually affordable, so have them checked out if your fuel economy plummets. 

Decrease in Acceleration

Accelerating a vehicle requires fuel combustion at a high temperature; if your spark plugs are not able to properly ignite your car's fuel in the combustion chamber, you will most likely notice that your vehicle has acceleration problems. Acceleration problems can include hesitation by the vehicle when applying the gas pedal, or a delayed time in reaching the speed that you want your vehicle to drive at. 

Rough Idling

When spark plugs are in good working order, an engine should have no problem idling while in park or stopped at a traffic light. But when spark plugs are going bad, it is not uncommon for an engine to experience a rough idle. During a rough idle, an engine may produce strange sounds and begin to stumble while at a stop. You may also notice that the RPMs fluctuate greatly while idling if the spark plugs in your car are failing. 

Contact an auto service for more help.