A misfiring engine can cause everything from sudden jolts to loud sputtering noises to an almost immediate, temporary loss of power, all of which can be extremely frightening when driving down the road.

Every driver should understand what a misfire is, what it signifies, and what causes it. Perhaps most importantly, you should know the steps necessary to resolve the issue and prevent it from recurring. Christian Brothers Automotive provides a comprehensive breakdown to help you stay safe on the road.

What Is an Engine Misfire?

An engine misfire is the name for what happens when the expected combination of air, fuel, and an ignition spark doesn’t combine under pressure to create the intended explosion, which makes your engine work. Instead, you get a premature or late explosion, or an explosion that creates that loud, unexpected pop.

This abnormal explosion is known as a misfire and can cause your entire car to suffer.

Signs of an Engine Misfire

A misfire rarely stays quiet. Your car tells you something is wrong well before a dashboard light comes on, and knowing what to watch for helps you catch the problem early.

• A rough or shaky idle
• Hesitation or jerking during acceleration
• A sudden loss of power
• A popping or sputtering sound from under the hood
• Lower fuel economy than usual
• An illuminated check engine light

Is It Safe to Keep Driving with a Misfire?

Driving on a misfire puts more than your commute at risk. Unburned fuel can travel into your exhaust system and overheat your catalytic converter, turning a simple repair into a far more expensive one. A misfire does not usually mean your engine is on the verge of failing, but letting it go unaddressed long enough can lead to real engine damage.

The longer a misfire continues, the more it costs you in fuel economy, engine performance, and eventual repair bills. If your car is misfiring, limit your driving and have it looked at as soon as you can.

What Causes an Engine Misfire?

Worn spark plugs and failing ignition components cause the majority of engine misfires, though fuel delivery problems and mechanical wear can produce the exact same symptom.

An engine misfire can be caused by a number of different things. After all, your engine depends on dozens of parts and systems working together simultaneously with precise timing in order to function as intended. When you think about it, modern engines working so reliably and smoothly for as long as they do with such high demands on timing and part integrity is nothing short of a modern engineering miracle.

As you might imagine, this means there are several different things that are pretty common causes of misfires, but they can pretty much all be classified into one of three different categories: your fuel system, your ignition system, and or another mechanical cause.

Your Ignition System

When air and fuel combine in your cylinder, they need a spark in order to ignite them and cause the explosion, which provides you with the power you need. When they don’t get that explosion, the cycle still continues, and more air and fuel combine.

In most cases, this simply means you have a faulty or intermittent spark plug (an issue with the ignition coil is also very common). As spark plugs wear and corrode, they lose their ability to ignite on command. In most cases, replacing your spark plugs will solve a misfire problem. You should also check your ignition wires to make sure they haven’t corroded or worn out. These are also simple and inexpensive to replace.

Your Fuel System

Your fuel system: If your ignition system checks out, then move on to your fuel system. Misfires related to fuel system issues are far more noticeable at idle or low speeds than at highway speeds. A misfire could be caused by not enough fuel getting into your cylinder, leading to an oxygen-heavy explosion.

There’s also a slim chance you could have simply filled up your car with a tank of gas that has gone bad. Your fuel injectors, fuel pump, and fuel filter all help regulate how much fuel enters each cylinder, and a faulty sensor that misreads your air-fuel mixture can throw that balance off as well. We recommend visiting a trained technician to evaluate all possibilities.

Your Mechanical System

Lastly, mechanical issues could be what is causing your misfire. First, check your vacuum lines connected to the intake manifold to make sure they aren’t leaking or cracked in some way, since a vacuum leak throws off your air-fuel mixture the same way a fuel system problem would.

There’s also a chance your timing belt or chain may have jumped or slipped.

Worn piston rings or lost compression in one or more cylinders can cause the same symptom, particularly in older, high-mileage vehicles. Whatever your mechanical cause may be, these are not problems that simply go away on their own.

If your car is experiencing any of these issues, it’s best to seek professional help immediately because an engine misfire is a serious problem.

How Is an Engine Misfire Fixed?

Fixing a misfire starts with figuring out which system is behind it, and pinpointing that cause is exactly the kind of diagnostic work our technicians handle every day.

• A technician pulls the diagnostic codes from your car's computer to narrow down which cylinder or system is misfiring.
• Worn spark plugs, ignition coils, or wires get tested first, since they cause the majority of misfires and are the simplest to replace.
• If the ignition system checks out, the technician moves to fuel delivery and checks your injectors, fuel pump, and fuel filter for a restriction or failure.
• Vacuum leaks, a slipped timing belt, or worn piston rings get inspected last, since these mechanical issues take more time to diagnose and repair.

Get Engine Service at Christian Brothers Automotive

When your engine is misfiring, Christian Brothers Automotive can help you get it fixed. We have trained and certified technicians who service all makes and models of vehicles. We pride ourselves on customer service, ensuring you receive an auto repair experience that greatly surpasses your expectations and leaves you completely satisfied.

Plus, we even make getting your repair simple with a free courtesy shuttle and comfortable waiting area!

Got a misfire problem? Find your local Christian Brothers Automotive today.