Engine misfires can be annoying, but they’re not always a sign of a catastrophic failure. Learn more about them in this post by Syntex Lubricants in Austin & Kyle, TX, so you can prevent them and avoid bigger issues.

A misfiring engine is one of the most common yet frustrating car problems. It can make your car run rough, reduce fuel efficiency, and even lead to costly repairs if ignored. But what exactly causes an engine to misfire, and how can you fix it before it gets worse? This guide will break down everything you need to know about engine misfires—what they are, why they happen, and how to resolve them.

Call Syntex Lubricants in Austin & Kyle, TX at (800) 890-0220 or visit AMSOIL's online shop to ensure your engine will remain as healthy as possible.

What Is an Engine Misfire?

An engine misfire occurs when one or more cylinders in the engine fail to ignite properly. Since combustion is necessary for your engine to generate power, any interruption in the process can lead to reduced performance, shaking, and even stalling. Misfires can happen occasionally or persistently, and they typically fall into three categories:

1. Ignition Misfires – Caused by spark plug or ignition coil issues.
2. Fuel Misfires – Result from fuel system problems, such as clogged injectors.
3. Mechanical Misfires – Occur due to internal engine damage, like worn valves or pistons.

Common Symptoms of an Engine Misfire

If your engine is misfiring, you’ll likely notice one or more of the following symptoms:

• Rough idling – Your car may shake or vibrate more than usual when at a stop.
• Loss of power – Acceleration feels sluggish, or the engine hesitates.
• Check engine light (CEL) turns on – The onboard diagnostics system detects a misfire.
• Unusual sounds – Popping, coughing, or backfiring noises from the engine.
• Increased fuel consumption – A misfiring engine works harder, burning more fuel.
• Excessive exhaust emissions – The car may emit black smoke due to unburnt fuel.

Don’t ignore these issues, as they can lead to further engine damage.

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What Causes an Engine to Misfire?

1. Faulty Spark Plugs or Ignition Coils

Spark plugs ignite the air-fuel mixture in your engine, and ignition coils provide the necessary voltage. Over time, these components wear out, leading to weak or inconsistent sparks.

How to Fix:

• Replace worn-out spark plugs (typically every 30,000-100,000 miles, depending on the type).
• Inspect ignition coils and replace faulty ones.

2. Clogged or Faulty Fuel Injectors

Fuel injectors deliver the right amount of fuel to each cylinder. If they get clogged or fail, the engine won’t get the proper fuel-air mixture, causing misfires.

How to Fix:

• Use a fuel injector cleaner to remove deposits.
• If the problem persists, have a mechanic inspect and replace the faulty injectors.

3. Low or Contaminated Fuel

Using low-quality gasoline or running on an almost-empty tank can cause misfires, especially if debris gets sucked into the fuel system.

How to Fix:

• Always use the recommended fuel grade for your car.
• Avoid running your tank too low to prevent fuel sediment from clogging the injectors.

4. Vacuum Leaks

A vacuum leak can disrupt the air-fuel ratio, making combustion uneven and leading to misfires.

How to Fix:

• Inspect vacuum hoses for cracks or disconnections.
• Replace any damaged hoses to restore proper airflow.

5. Sensor or ECU Malfunctions

Modern cars rely on sensors (like the oxygen sensor and mass airflow sensor) to regulate fuel and air delivery. A malfunctioning sensor can send incorrect data to the ECU (engine control unit), leading to misfires.

How to Fix:

• Use an OBD-II scanner to diagnose faulty sensors.
• Replace malfunctioning sensors as needed.

6. Timing Issues

If your engine’s timing belt or chain is worn out, the combustion cycle may become uncoordinated, causing misfires.

How to Fix:

• If your car has high mileage, inspect the timing belt or chain and replace it if necessary.

7. Internal Engine Problems

More severe misfires can stem from internal engine issues, such as damaged valves, worn piston rings, or low compression.

How to Fix:

• If misfires persist after addressing common causes, have a mechanic perform a compression test.
• Major repairs may be needed, such as valve replacements or an engine rebuild.

How to Prevent Engine Misfires

While some misfires happen unexpectedly, regular maintenance can help prevent most of them. To keep your engine running smoothly:

• Change spark plugs and ignition coils as recommended – Don’t wait until they fail.
• Use high-quality fuel – Cheap gas can lead to buildup and clogging.
• Keep up with oil changes – Dirty oil can cause wear and tear on engine components.
• Inspect vacuum hoses and sensors regularly – Small issues can turn into big problems.
• Follow your car’s maintenance schedule – This helps catch potential problems early.

Call Syntex Lubricants in Austin & Kyle, TX at (800) 890-0220 or visit AMSOIL's online shop to find the products that will help you prevent engine misfirings!