That’s A Misfire: How to Tell if A Spark Plug is Bad

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Small but mighty. That’s the motto of the spark plug. 

Spark plugs are what get your car engine revving. The spark of electricity that comes from the plug creates the combustion needed for your car to start. 

To put it bluntly, if your spark plugs aren’t firing away, you’re not going anywhere.

Spark plugs are a vital part of your car, but do they require upkeep? How long do they last? And how are they replaced?

Read on to learn everything on how to tell if a spark plug is bad.

How to Tell if a Spark Plug is Bad

Just like motor oil, air filters, and fuel filters, spark plugs need regular maintenance to make sure they are in top-firing condition. For most vehicles, it is recommended to replace the spark plug every 30,000 to 50,000 miles.

Although some newer models claim that spark plug replacement isn’t necessary due to new technology.

No matter what car you drive, here are some tale-tell signs that a spark plug has gone bad. 

Hard to Start

You’ve seen the cartoons: an old car is trying to start and it keeps misfiring. Someone needs to do them a favor and tell them they have a bad spark plug.

Bad spark plugs cause the car to feel jerky and erratic. Or not allow the car to start at all. 

In order for a car to start, there are multiple components that must work in perfect timing, one of which is the spark plug. To get a better idea of what exactly is going on, look here

Knocking Noises

These knocking noises coming from your car is from the force of the pistons and combustion not working properly.

The pistons move very rapidly, and if the spark plug is delayed, it will lead to rattling and knocking sounds.

Slow Acceleration

If you’re finding that it takes longer and longer for your car to go from 0 to 60, it could be the spark plugs. 

When a car has poor acceleration, it is usually due to a problem with the ignition system. In modern engines, it could be one of the sensors is faulty, but sometimes it really is a bad spark plug. 

If a spark plug can’t get hot enough to produce a spark, the vehicle won’t accelerate as it should. So if your car isn’t picking up like it used to, you may need to do some spark plug maintenance.

Poor Fuel Economy

When spark plugs are working properly, they help burn fuel efficiently in the combustion cycle. When a spark plug is worn out, or not properly spaced, the vehicle will often have lower fuel economy. 

So if you find yourself paying at the pump more often than you’d like, it’s time to make sure your spark plugs are in pristine condition.

Engine Misfiring

A damaged spark plug wire or tip can an engine to misfire. This can sound like sputtering or stumbling sounds from the engine. If it’s not fixed, you will experience an increase in exhaust emissions and a decrease in engine power.

And let’s be honest. No one wants that. 

You Won’t Miss the Misfires

If your car isn’t running up to speed, use these tips to find out how to tell if a spark plug is bad.

The good news is it can be a relatively easy fix. So whether you want to find a good mechanic, or try it yourself first, it’s better to do replace those worn out spark plugs sooner rather than later.

And while you’ve got your head under your hood, take a look to see what else needs to be fixed. And if you have any questions, we’ve got answers.