What Is an Engine Misfire? Causes & Prevention

What Is an Engine Misfire? Causes & Prevention

What Is an Engine Misfire

Berryman Products provides practical solutions, such as engine-friendly fuel treatments, boosting your vehicle’s performance and preventing engine misfires. Below, we will delve into the causes of a misfiring engine and what you can do to avoid it.

engine misfire, detonation, slower acceleration, shaking during acceleration

What Is an Engine Misfire?

An engine misfire occurs when one or several cylinders in a car’s engine fail the detonation of the air-fuel mixture. Engines are designed to ignite this combustible mixture in a timely and efficient manner. A misfire can cause several problems with your vehicle, such as slower acceleration, rough idling, check engine light, and shaking during acceleration.

Symptoms You Should Look Out For

The symptoms of a misfiring engine can occur at any time, so you should pay attention to its symptoms. The signs often occur during startup and acceleration or when your engine idles before coming to a halt.

  • Sluggish/Slower Acceleration: Your car will appear to have trouble accelerating. This symptom is due to the fact that the engine is under load when you step on the gas pedal. You often feel a jerking motion from your car or shaking during acceleration.
  • Rough Idling: Aside from slower acceleration, an uneven idle is another common symptom of a misfired engine. It can be a strong indicator that there’s something wrong and you should bring your car to a mechanic. A bad or rough idle means that the detonation of the air/fuel mix has been disrupted, making the car jump up and down slightly.
  • The Engine Making Strange Sounds: A misfiring engine will sound different from the usual rhythmic pattern engines usually make. The odd sounds are like chuffing, banging, and popping sounds, and they typically occur when the engine is running between 1,500 to 2,500 rpm.
  • Check Engine Light: When the check engine light turns on, it means there is something wrong with the engine that requires your immediate attention. Other symptoms can often accompany this indication, like shaking during acceleration.
  • Black Smoke from the Exhaust: When a cylinder fails at detonation, the fuel/air mix can ignite at the exhaust, which causes a thick cloud of black smoke to come out of the pipe. This can indicate that one or more cylinders are not working correctly.

Causes of a Misfiring Engine

A misfire in your car’s engine can result in many issues. Sometimes it can be due to fuel-related problems or caused by a fault in mechanical parts like the fuel injector. The following are some of the most common causes of an engine misfire:

1. Faulty Spark Plugs
Spark plugs are crucial in fuel combustion in a vehicle’s engine. It can cause problems in the ignition system when worn out or damaged.

2. Bad Ignition Coil
Another cause for a misfiring engine is a worn-out or failing ignition coil. Many vehicles today have one ignition coil for every spark plug, but others are designed to have one ignition coil pack with ignition wires that attach to each spark plug. Each of these parts can contribute to a poor spark, which causes misfires.

3. Low Fuel Pressure
When the fuel pressure drops, less fuel will enter the engine’s combustion chambers. The reduced amount of fuel makes the air/fuel mixture lean, thus causing a misfire. You can check the pressure using a manual air pressure gauge.

4. Leaks in the Intake Manifold Gasket
This gasket is located in between the intake manifold and the cylinder head. When this gasket leaks, it draws air into the combustion chamber, making the air/fuel mixture too lean, causing misfires.

5. Faulty Fuel Injector
The fuel injector is part of your car that supplies the right fuel to the combustion chamber. Each of the cylinders in the engine will have a separate fuel injector. When an injector is faulty or damaged, the chamber it is installed in will get the wrong amount of fuel, which means there can be too little or too much fuel in the mixture causing a misfire.

Bad fuel injectors are one of the last things you should check since they rarely fail in many modern car models. It would be best to inspect the other possible culprits of a misfiring engine first.

However, if you’ve checked every other part and nothing seems to be wrong, here are some of the symptoms of a failing fuel injector that you should pay attention to:
-Check engine light
-Increased fuel consumption
-Too much engine vibration
-Engine stalling
-Bad fuel odor
-Fuel leaks
-Your car fails emission testing

If everything checks out upon inspection, but you’re still getting the signs listed above, it can mean that you have a faulty fuel injector. Taking your vehicle to a skilled mechanic to diagnose the engine trouble correctly is best.

6. Bad Engine Sensor
Modern vehicle engines have multiple sensors to ensure that it is running efficiently. When an engine sensor goes bad, it won’t be able to detect the correct air-to-fuel mixture, which will cause a misfire. The sensors your mechanic will check include the oxygen sensor, the MAP sensor, and the MAF sensor.

Fixing Engine Misfires

When you bring your car in for a checkup or repair at the shop, your mechanic will go through every potential cause of a misfiring engine. Here are some things you should expect during the diagnosis and repair phases.

  • OBD2 Scan: An onboard diagnostic II scanner is a diagnostic tool that will help you quickly identify which part is failing. Some units can even pinpoint which cylinder is misfiring.
  • Spark Plugs and Coils: Spark plugs and coils may have to be replaced.
  • Fuel Pressure Check: Checking the fuel pressure will help determine if you’re getting the right fuel/air mix.
  • EVAP Smoke Machine: An Evaporative Emission Control smoke machine can test for vacuum leaks to determine where the air leaks.

Some of the tools mentioned here are expensive, and most car owners won’t have them in their garages. It is best to bring your car to a mechanic when you see the symptoms of a misfiring engine mentioned in this guide.

Caring for Your Engine with World-Class Products

Getting regular maintenance and using high-quality car products will help prevent misfires. At Berryman Products, we supply our customers with effective industrial-grade solutions to care for your car’s engine and prevent misfires. Call us today or fill out this form to ask a question, and our specialists will be happy to answer your questions.

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