Is it bad to drive? What are car cylinder misfires, engine causes, & meaning

Engine misfires can be commonly spotted on busy streets where several older vehicles are experiencing them. The result is a thick cloud of black smoke from the exhaust pipe. Additionally, the car will sputter and slow as the engine misfires.

When the engine cannot complete the combustion process inside its cylinders, it indicates that something is wrong with your vehicle. Drivers are confused and wonder whether it is bad to drive their cars or not. 

Whether you are driving a Chevy or any foreign car, it is important to know all the symptoms of this problem. Continue reading to find out what are car cylinder misfires, what causes it in the engine, and their meaning. 

By the end of the article, you’ll know there are different error code you can come across:

  • P0301
  • P0302
  • P0303
  • P0304
  • P0305
  • P0306
4-cylinder engine

What is a misfire in a car?

There are 3 essential components that the engine needs to operate the cylinders efficiently. It relies on fuel to burn and oxygen to facilitate this reaction. A spark will light up the mixture to produce the necessary power.

When one of these elements is missing, the cylinder will not be able to finish the combustion process. As a result, an engine misfire will occur. These misfires can happen either when you start the engine or when it is idling. The engine will stumble and lose RPM, which can be inconvenient when cruising. 

Symptoms of a misfire

When your engine misfires, you will notice a couple of symptoms. They let you know that there is something wrong with your car, and you can identify the exact problem by paying attention to these warning signs

Rough idling

When you stop at a red light, you will notice increased vibration and uneven operation of your engine. The symptoms are the same whether you drive a VW Passat or a Ford. It happens because the cylinder becomes compromised and makes the engine work incorrectly.

Sluggish acceleration

Once the red light turns green, the struggle to accelerate will be obvious. Reaching higher speeds is difficult when the engine is misfiring. As you press the gas pedal, you will feel a bumpy motion making it difficult to drive your car.

Engine sounds

If you bought your vehicle years ago, you are probably already used to its engine sound. When the engine misfires, it will produce a different noise which you can notice quite easily. When weird sounds come from the engine bay, you are likely dealing with misfires.

Black smoke

Once the engine misfires, black smoke can be noticed in your rearview mirror. It indicates that the engine is passing fuel and air incorrectly. It is also an environmental issue, so you might want to solve this problem as soon as possible.

Causes of a misfiring engine

While symptoms will make the problem obvious, you must also identify the causes of a misfiring engine. All engines misfiring situations share the same causes. From Hyundai to Jeep and Dodge, here are the most common causes of an engine misfire.

Ignition system

Engine misfires are often associated with failing spark plugs. But spark plugs are just one part of the ignition system, which contains many more components. Any of them could fail and cause a misfire. 

spark plugs

Air and fuel delivery

When these elements are mixed, they generate power once the spark plug ignites them. If there is an issue with air and fuel delivery, you will notice it through the symptoms presented above.

Emissions equipment

Some newer models have special emissions equipment designed for environmental protection. Ventilation systems and exhaust improvements will reduce pollution caused by your car. Still, they can also cause misfiring when not working properly.

Mechanical issues

Each cylinder has a piston that compresses the mixture to complete combustion. Some mechanical problems will prevent this simple operation or make it more difficult. As a result, the car misfires when accelerating. 

How to diagnose a misfire

When diagnosing an engine misfire, you must look for specific diagnostic trouble codes. To identify the problem easily, these codes will help you narrow down the possible causes and focus on any possible malfunction. 

Special diagnostic tools are used for this process, which will display a specific code on their screen. Some advanced ones can even tell you how many misfires occurred in a certain amount of time. You can also find the exact RPM when the misfire happened. 

There are many diagnostic tools on the market. While some are highly practical, others focus too much on extra features instead of basic tasks. After searching the market for hours, we found the perfect product that includes both efficiency and comfort.

MOTOPOWER MP69033 Car OBD2 Scanner Code Reader Engine Fault Code Reader

MP69033

MOTOPOWER is a well-known company that produces tools and devices designated to help you with your vehicle. This particular model has lots of practical functions. A built-in library allows you to identify the problem without further research quickly.

You can also get vehicle information, engine coolant temperature, and even the engine speed. It is a highly practical tool that does wonders in anyone’s garage. It supports 6 languages with English as default. But if your Japanese friend needs it for his Honda, his native language is also available.

With a compact design, this tool is easy to hold and will not make your hands feel uncomfortable after prolonged use. The LCD display brightly displays information on a large screen with a white backlight. This device won’t need any batteries since it gets power directly from your vehicle. 

This performant diagnostic tool will display several codes on the screen. Each of these codes has a specific meaning, and you can use them to identify your problem precisely. Now we will discuss the most popular ones related to engine misfiring. 

Brand‎MOTOPOWER
Batteries‎1 Lithium Ion battery is required. (included)
Country of Origin‎China
Item Weight‎9.9 ounces
Product Dimensions‎6.02 x 2.75 x 0.91 inches

Pros

  • It’s not a very expensive code reader.
  • It gets the job done.
  • It’s very intuitive.
  • Keep one of these in each of your cars.

Cons

  • You can get more advanced readers if you spend more money.
  • You can get a free engine check at AutoZone.
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MOTOPOWER MP69033
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MOTOPOWER MP69033
It will help you understand what is going on with your car.

P0301 cylinder-1 misfire detected

This code means that the powertrain control module detected a misfire from the first cylinder. The code lists the cylinders numerically, and you will know which one of them encountered problems. Incomplete combustion in the first cylinder is signaled through the P0301 code.

P0302 cylinder-2 misfire detected

P0302 code signals you about cylinder two. The combustion process is incomplete within the chamber and doesn’t receive the necessary spark for ignition. This code also comes with a blinking check engine light on the dashboard. 

P0303 cylinder-3 misfire detected

There are many reasons why the P0303 code might appear on the screen of your tool. They are all related to engine misfires and tell you that the cause comes from the ignition system or the fuel system.

P0304 cylinder-4 misfire detected

Once the P0304 code is displayed, it is time to look toward the spark plugs and coil packs. This code warns you about a possible internal engine failure that is caused by these parts.

P0305 cylinder-5 misfire detected

This code is related to the 5th cylinder, and it tells you that it has a problem. The combustion process cannot be completed, and the powertrain control module has detected a misfire in this cylinder. 

P0306 cylinder-6 misfire detected

The air and fuel mixture in the 6th cylinder is not being ignited. As a result, the P0306 code appears on the screen. A mechanic can investigate this problem further and now easier since he knows where the cause comes from. 

2014 Ford taurus SEL Sedan 4D

Random/multiple cylinder misfire detected

When the exact cylinder is unknown or when the misfire happens in multiple cylinders simultaneously, the P0300 code is shown. A deficiency in burnt fuel within a cylinder can cause this problem. 

How do you fix a misfiring cylinder?

Fixing a misfiring cylinder is not complicated, but you need some basic skills in engineering and mechanics. If you are unsure how to proceed with the reparation process, seek the help of a skilled mechanic. Most auto repair shops are already equipped with all the necessary tools to diagnose and fix this problem.

Spark plugs often cause this problem, so you can start with them if you plan to fix the problem yourself. Inspect the spark plugs for signs of damage and determine their condition. You can also use a multimeter to test the coil pack. With this tool, you can compare the resistance with one of your cars. 

If the spark plugs are functioning properly, continue by doing a compression test. This operation is not complicated, and you can find video tutorials made for your specific model. If there is a problem with compression, replacing the head gasket will be the best solution. 

When does my engine misfire?

Most of the time, engine misfiring occurs during acceleration when the throttle is pressed. While this is not harmful to the engine, it can make your car too dangerous for public roads. A sluggish acceleration might put the safety of other drivers at risk because your car cannot reach the necessary speeds.

Additionally, this problem will also be an inconvenience for other drivers, especially when you perform a standing start. If you are the first in line at a red light, expect lots of horns as your car struggles to start rolling. That is why you should fix this problem as soon as it occurs.

2005 Hyundai santa fe GLS Sport Utility 4D

Misfirings can happen during idling as well, where the engine will stutter, and vibrations will increase as you come to a stop. In this case, injectors and the oxygen sensor might need to be cleaned or completely replaced. 

Engine misfires when accelerating

As spark plugs suffer from excessive wear, you will start experiencing engine misfirings when accelerating. These parts are responsible for igniting the fuel mixture in the cylinder. But if they cannot function properly, the engine will suffer. 

You should solve this problem as soon as possible because a cylinder misfire can cause major engine damage. It is not one of those problems which you can postpone as late as possible. It is not recommended to drive a vehicle that suffers from engine misfires. 

The slow and sluggish acceleration is also a problem for those around you in traffic. Other drivers will notice the inconsistency in your vehicle’s performance and will struggle to adapt to these driving conditions. The black smoke from your exhaust will also be a problem for their visibility. 

Car misfires at idle

While some of the issues can occur while cruising down the highway, engine misfires can also happen when you are idling. When you stop and notice a rough or uneven idling, this can be considered a good indicator of the engine misfiring.

It happens because the fuel mixture is not ignited properly, and the combustion process is incorrect. A check engine light might appear on your dashboard, informing you about a serious issue. Sometimes this light comes with a code, and you can identify the problem better.

If no code is shown on your dashboard, consider getting a performant tool like the one recommended in this article. Such devices can pinpoint the problem accurately, and you will know what needs to be fixed. 

What does an engine misfire feel like?

In order to identify this problem quickly, it is important to pay attention to symptoms and signs. If you know what an engine misfire feels like, you will be able to act accordingly. An inexperienced driver will try to guess the problem, but you can determine it precisely.

The most obvious symptom you can feel is during the acceleration from a standing stop. The car will feel weird and different from how it used to be when you first got it. The engine might stumble and struggle to work properly. Eventually, it should resume its normal pace.

It happens because there is an incorrect fuel mixture in the cylinders. A faulty oxygen sensor can cause this, and you might have to replace this part. 

oxygen sensor
So what is the error code you’re seeing?
  • P0306
  • P0305
  • P0304
  • P0303
  • P0302
  • P0301

    FAQ

    Is a misfiring cylinder expensive to fix?

    You should expect to pay between $100 to $1,000 to fix this problem. The reason for the misfiring greatly influences the reparation cost, and you also have to consider the labor fees if you don’t fix this problem yourself. 

    Can I drive with a cylinder misfire?

    You can still drive a car that suffers from a cylinder misfire. However, this is not recommended because you will struggle with keeping your car under control, especially when accelerating. The black smoke from your exhaust will also increase pollution and damage the environment. 

    Can an O2 sensor cause a misfire?

    A malfunctioning oxygen sensor can often cause an engine to misfire. It delivers wrong information to your vehicle’s computer. As a result, the fuel mixture will be compromised with an incorrect amount of air and fuel. 

    Can a bad spark plug cause misfire?

    Bad spark plugs and failing ignition coils will also cause this problem. The combustion effect is delayed, and you will experience issues when accelerating. The cylinders are not producing enough power, and your car will struggle to move. Additionally, you will also notice that the engine is making odd noises. 

    Can a catalytic converter cause a misfire? 

    The catalytic converter is the most expensive part of your vehicle, mainly because it has precious metals in its structure. This part is mandatory for every car as it lowers emissions and keeps the environment safe. But the catalytic converter can also cause your car to misfire and interfere with the combustion process.