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5 Ways to Tell if a Spark Plug is Bad

March 20, 2024 | Victor Lukasso

Sometimes, it takes just a replacement of one of the minor components of the vehicle (The spark plug) to improve its performance significantly. The spark plug plays a massive role in maintaining your vehicle’s performance.

Therefore, you must observe the signs of bad spark plugs and get new ones regularly to help your vehicle perform at its best. But how do you know if your spark plugs are bad and need replacing? In this article, I will educate you on how to know if a spark plug is bad.

What is a spark plug?

A spark plug is a small electrical device that triggers combustion in a vehicle’s engine. It ensures or provides the spark needed to ignite the air and fuel mixture in the engine’s combustion chambers to generate power for the machine. Thereby causing the vehicle to ignite, stay powered, and run smoothly.

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How Long Does a Spark Plug Last?

Usually, a spark plug can last up to 100,000 miles, about 160,000 km, but it may need replacing earlier if you notice any issues.

However, always check your vehicle’s manual to see when it recommends changing the spark plugs and to know the spark plug with the proper gap sizes to create a spark vital enough for your engine.

What are the Benefits of Replacing a Bad Spark Plug?

The primary benefit of replacing your spark plug is that you know that your vehicle will be in perfect condition and fire up without any glitches. New spark plugs provide a lot of performance benefits, such as

1. Optimal combustion.

A functional spark plug is crucial for proper combustion system operation, which can alleviate many performance issues.

2. Reduces harmful emissions.

When there is proper car maintenance and care, like regular replacement of bad spark plugs, it helps to increase the efficiency of the fuel and thereby reduces air/environmental pollution.

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3. Economize fuel usage

When spark plugs misfire, it can reduce fuel efficiency by almost 30%. Therefore, getting a new plug could help you maximize fuel use in your vehicle and save you some money.

4. Smooth start/ fast ignition

When a car’s spark plug changes, you will notice a difference in the ignition rate. A lousy spark plug is the reason for delayed ignition in a vehicle most of the time.

How to Tell if a Spark Plug is Bad

There are quite a handful of whole ways of diagnosing a bad spark plug. Some of these include:

1. Reduced gas mileage

A bad or deteriorated spark plug may likely cause reduced gas mileage. When spark plugs work correctly, they burn the engine’s fuel efficiency.

This results because the space between the plug electrodes may expand or reduce as a spark plug ages, which could result in the spark plugs not firing or firing erratically, causing wastage of fuel and increasing emissions.

2. Lack of acceleration/ slow acceleration

When you press down the acceleration pedal on your vehicle and the vehicle responds slowly or not as quickly as usual, the spark plugs could cause a delay in response.

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3. Hard starting

When a spark plug is worn out, it produces current with little or no ability to ignite the engine. It usually makes a sputtering noise and may take longer than usual for your machine to roll over as you turn the ignition key.

4. Rough idling

A bad spark plug can cause your engine to sound rough or even vibrate while idling. When you start your vehicle’s engine, you hear any rattles, metallic pings, or sputtering rather than a smooth, even sound. An old or lousy spark plug won’t allow fuel to burn completely, which may result in the engine vibrating or making some unpleasant noises.

5. Engine Misfires

Another big sign that a spark plug is bad is when the engine isn’t firing correctly. This misfire may often sound like a sputtering sound, or you may feel like there is a sudden loss of power or violent shaking. If the misfire becomes consistent, it may result in poor performance of the vehicle, low fuel economy, higher exhaust emissions, and even damage to the catalytic converter.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.