Can Bad Spark Plugs Cause Engine Shaking And Loss Of Power?


Car engines have plenty of moving parts, yet they don’t shake violently. That’s because they’re designed to work harmoniously together and only produce light vibrations. So, if the engine starts shaking and shows signs of power loss, the likely cause is a bad spark plug.

Spark plugs combust the air and fuel mixture in your engine’s chambers to generate power. They’ll cause that combustion process to become unreliable when they go bad. That will cause the engine to misfire and shake while simultaneously failing to produce power when accelerating. Cleaning your bad spark plugs might help, but replacing them will solve the problem immediately.

Read through this guide to better understand what spark plugs are and how they work. Then, you’ll learn how they cause engine shaking and loss of power, and what you can do to solve the issue.

What Are Spark Plugs, And How Do They Work?

Firstly, it’s important to understand what spark plugs are and how they function. Doing that will enable you to understand the kind of problems they face and how they affect your engine’s performance.

Car engines have several spark plugs working at the same time to generate sparks. Those sparks are necessary to ignite the mixture of air and fuel in the engine’s chambers, creating combustion and generating power to move the vehicle forward.

Spark plugs are designed to withstand plenty of wear as they continuously generate sparks for as long as the engine is turned on.

When an engine’s spark plugs are in excellent working condition and function correctly, the engine’s chambers will combust air and fuel continuously without any problems. That engine will continuously generate soft vibrations and a gentle humming sound when everything runs smoothly.

Spark plugs generally last 100,000 miles or more, but they’ll wear out like any other car part. They can even wear out prematurely if the engine isn’t well-maintained with regular oil and filter changes.

So, despite how durable your spark plugs are, they’ll eventually get too dirty and worn out to generate the sparks necessary for combustion reliably.

When that happens, the engine will begin experiencing many different problems, including engine shaking and power loss.

Read: Denso vs NGK – Which Spark Plugs Should You Use?

How Do Bad Spark Plugs Cause Engine Shaking?

When your engine starts shaking, that’s a telltale sign that something is wrong with one or more of its spark plugs. 

Normally, an engine has many moving parts inside, like its crankshaft and pistons. Despite that, the engine doesn’t shake violently because those parts are designed to move harmoniously.

The problems start to happen when one or more spark plugs have gone bad. Dirty or worn-out spark plugs can’t generate sparks for the combustion process, so the fuel and air mixtures in some of the engine chambers won’t ignite.

When only some chambers ignite, but others don’t, the engine’s components no longer move harmoniously. As a result, the whole engine shakes violently.

You must never overlook a shaking engine or delay getting it fixed. That’s because the excess vibrations from the engine will lead to other problems, such as the following:

  • Discomfort: Firstly, you and your passengers will be uncomfortable inside a car with a shaking engine. The excess vibrations don’t just cause discomfort for occupants, but it also creates sounds that make the driving experience even worse.
  • Distracted driving: Noise and discomfort are two things that distract car drivers. They will take your attention away from the road and raise your risk of getting into a car accident.
  • Premature wear: Your car has plenty of fasteners that keep parts attached to the frame. Excess vibrations and shaking will cause them to wear out prematurely. One example is the engine mounts that keep your engine secured to the vehicle’s frame. Too much shaking will stress those mounts and cause them to wear out quicker than usual.

As you can see, engine shaking can lead to many bigger and more expensive problems if it’s not resolved quickly. Spark plugs are small parts, but they can trigger all the problems described above.

Read: Why Is There Oil On My Spark Plug Threads?

How Do Bad Spark Plugs Cause Power Loss?

Power loss is what happens when your engine’s combustion process doesn’t occur as efficiently as it should. That will lead to a cascade of different problems, from a drop in horsepower to lower fuel efficiency. 

Overall, your vehicle won’t perform at its best, especially when you need it the most. The root of the problem is simple: one or more of your spark plugs have gone bad.

Earlier, you read about how worn-out spark plugs fail to deliver strong sparks to combust air and fuel mixtures. Unfortunately, a spark plug that can only generate weak or inconsistent sparks is also considered one that’s gone bad.

For example, spark plugs often become fouled or develop a carbon buildup at the tip. That small buildup will cause weak acceleration and a lack of power output even when you try to accelerate at higher RPMs.

These might not sound like major problems initially, but they can also severely undermine your driving.

Firstly, the power loss will make your driving much more unstable because of the engine’s erratic behavior. For example, you’ll find yourself without enough power to drive up steep inclines, like going over a hill.

Besides that, your engine won’t give you the power you need when you try to avoid dangers while driving on the road.

Needless to say, that’ll put you, your occupants, and other road users at risk as your vehicle becomes unreliable and unresponsive to your input.

Read: 5 Ways to Improve Poor Fuel Economy of Your Car

What Do You Do When Spark Plugs Go Bad?

Some bad spark plugs are worse than others, so you have different ways to solve engine problems like shaking and power loss.

So, the first step to troubleshooting spark plugs is to remove them from the engine and inspect them closely. Of course, you should wait for your engine to cool down completely before you do that, preferably first thing in the morning.

Once you remove your spark plugs, you can first try to clean them thoroughly using the following:

  • A wire brush
  • Some sandpaper
  • A spark plug cleaner spray

Using those items will help you remove carbon buildups and restore your spark plugs to optimal condition.

However, if the spark plugs are too worn-out, the best solution is to replace them with new ones. That way, you won’t have to worry about the engine shaking and loss of power happening again for a very long time.

Suppose only one or two spark plugs have gone bad. In that case, you’ll still want to replace all of them together at the same time. Think of it as a form of preventive maintenance.

If one of your spark plugs has gone bad, the others will likely go bad soon enough.

So, changing them simultaneously will save you time and effort in the long run.

Read: What Happens if You Put Diesel in a Gas Car?

Final Thoughts

As you can see, spark plugs can indeed cause engine shaking and loss of power when they go bad. Despite their small size and durability, they will eventually become dirty and worn-out and trigger a series of different problems for your car engine.

You can maximize your spark plug’s lifespan by cleaning them when they get dirty. However, changing them once they’re worn out is the most practical solution. Not only will that instantly solve your engine problems, but it’ll also last you many years to come.

Read: Weak Mechanical Fuel Pump Symptoms – Troubleshooting Guide

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