Why Do Cars Misfire? (11 Reasons Why)

Car engines are complicated pieces that can malfunction at any time. You may be frustrated with the issue, but you should know that your car’s failure is not necessarily because of poor quality parts.

While this is an undesirable situation, it doesn’t mean that there has been foul play or sabotage. Instead, it may be due to several different causes. Here’s what I am going to unveil why car engines backfire!

Why Do Cars Misfire?

1. Internal Engine Damage

A type of backfire known as a “misfire” results from after fires that spill out through the exhaust system of a car’s engine.

Besides that, an imbalance between air and fuel caused by dirty gas filters also causes engine combustion problems.

Consequently, you should have this checked out immediately if it occurs regularly without symptoms such as unusual noise and vibrations in the engine compartment.

As a result, internal engine damage and poor maintenance can potentially lead to engine misfires!

2. Worn Out Electrodes

Nowadays, many cars come equipped with an ignition coil instead of spark plugs.

In most cases, if there are old or worn-out electrodes in your coil, they won’t produce enough electricity to start your car.

Additionally, you may notice that your engine won’t start because there isn’t enough electricity flowing through them anymore.

Overall, it can develop into misfiring problems because no power will go into the spark plugs because of worn-out electrodes!

3. Faulty Spark Plug

A spark plug is responsible for igniting fuel in the cylinder, allowing it to turn into gas and power your car.

However, excessive wear on spark plugs prevents them from igniting the fuel in the piston cylinder as they should.

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Thus, clogged spark plugs, a broken distributor cap, or defective spark plug wires may be to blame for this.

Therefore, if there’s something wrong with the spark plug, it won’t ignite the fuel and won’t turn into gas, and worst case, it could progress to backfires!

4. Diagnostics System Error Codes

Engine fault codes, commonly called diagnostic trouble codes, are five-digit codes that pinpoint a specific issue with a vehicle.

On the other hand, a malfunction indicator lamp (MIL), referred to as the check engine light, merely notifies drivers that there is a problem.

In the event of system error codes, it will reflect with an engine misfire cipher to P0300 and P0312.

Because of this, if you have an engine management system error code on your dashboard, then this could also cause your car to misfire and must get immediate attention!

5. Clogged Fuel Injectors

An engine will misfire if a clogged fuel injector consistently struggles to distribute fuel to the engine. At some point, it will entirely miss the fuel supply.

That is why you will hear the sputtering when you press the accelerator while moving.

Furthermore, if the problem is related to a clogged fuel injector, this will cause the car to fail to start or run poorly!

Generally, while idling, your engine will misfire, which will cause your car to vibrate!

6. Failed Ignition Coil Packs And Wires

Failed Ignition Coil Packs And Wires

An ignition coil’s job is to increase a car battery’s low current to a level that will ignite the fuel and start the engine.

On the other hand, internal coil breakdown can be brought on by excessive heat and vibration. It can make a coil work harder, need more voltage, and drastically shorten its operational life.

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Consequently, your car will misfire as you speed if the ignition coil is broken. In extreme circumstances, a backfire might force your car to crash while driving!

7. Fuel Pressure Is Low

A car’s fuel system consists of two main parts: the fuel tank and the fuel pump. It delivers the fuel to the engine through an intake manifold that feeds into each cylinder.

On the contrary, low fuel pressure can result in difficult starting, rough idling, reluctance, and stalling.

As a result, if the fuel pump malfunctions while the vehicle is in motion, there won’t be any fuel pressure, making the engine stop running or direct to misfires!

8. Imbalance Air To Fuel Ratio

An imbalance in the air-to-fuel ratio inside the internal combustion chamber is one of the leading causes of an engine misfire.

Along with this, a specific ratio of fuel to air must be present in the mixture for combustion to take place successfully.

Therefore, cylinder misfires will appear when your car is idle. However, when you increase your pace, the misfire will go away!

9. Broken Cylinder

Some cylinder heads, like those on the Saturn engines, are susceptible to cracking due to design defects.

Furthermore, thermal stress causes the cylinder to shatter when an engine runs too hot. Even one instance of engine overheating might lead to a cracked cylinder head.

Due to this, when a cylinder breaks, this causes the spark plug to fizzle, which results in a misfire condition on your engine!

10. Vacuum Leaks

A vacuum leak can cause your car to run poorly due to loss of power and reduced fuel efficiency.

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As well as that, it can happen if the rubber hose connecting the fuel pump to your gas tank has been damaged or if something else has punctured it.

For that reason, vacuum leaks will cause the engine to idle unevenly and possibly misfire, mainly if they are limited to one cylinder!

11. Faulty Emission Systems

A vehicle’s emissions control system is designed to help reduce air pollution by preventing harmful gasses from entering the engine compartment.

In line with this, your car may not run correctly or meet emissions standards if you have a faulty emission system. Most often, it’s due to an issue with the catalytic converter.

In some circumstances, the engine’s air-fuel ratio could be altered by issues with emissions equipment to the point where a misfire happens!

To know more, you can also read our posts on why cars backfire, why cars catch on fire, and why older cars burn oil.


Understanding the engine’s operation is essential to determine why your car is misfiring.

When this occurs, you might experience internal engine damage, worn-out electrodes, and a defective spark plug.

Keep in mind that a car’s internal engine is an essential part of every vehicle. It is there to power the wheels, but it can also malfunction over time!

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