Although small in size, spark plugs play a key role in the function of a car's engine. When you turn the ignition, it causes these plugs to spark (hence the name); thus, igniting the fuel and creating the combustion necessary to power your car. But like most components in modern-day automobiles, spark plugs will eventually go bad. This typically doesn't happen overnight, rather years of driving with the same factory spark plugs will eventually result in failure to spark. So, how do you know when it's time to replacing your spark plugs?
Car Shakes When Idle
A tall-tale sign that your spark plugs are going bad is rough idling. If your car shakes when you idle at a stop sign or red light, it could be indicative of bad spark plugs. Of course, there are other possible causes of rough idling, such as a dirty throttle body. In any case, you should attempt to replace the spark plugs first since it's a quick and inexpensive fix.
Car Takes Several Turns to Start
When spark plugs begin to go bad, you may have to turn the ignition two, three or even four times just to start the engine. The good news is that your spark plugs aren't completely dead at this stage. But the bad news is that the problem will only become worse until you replace the spark plugs. So, don't wait until your car no longer starts before replacing them.
A third sign that your spark plugs are going bad is frequent misfires. This is due to the buildup of gunk on the spark plugs themselves, which subsequently causes one or more of the engine's cylinders to misfire. And if your car is misfiring, it may also be releasing excess emissions, in which case your car may fail its next emissions test (assuming you live in a state or city that requires them).
When you press down on the gas pedal, does your car take a while to accelerate? If so, it could be a sign of your spark plugs going bad.
How to Replace Your Spark Plugs
Thankfully, replacing the spark plugs isn't an overly complicated or difficult process. Depending on the make and model vehicle, you can often buy new spark plugs for about $10 to $15 bucks. The biggest expense is the labor, which can cost between $120 and $170. Refer to your vehicle owner's manual for more information on what type of spark plugs you need and how to replace them. Using just a few basic tools, you should be able to replace them yourself.