As car owners, there are few things more unsettling than your vehicle behaving abnormally, and this is particularly true for a misfiring engine. The telltale shudder and unpredictable performance that comes with an engine that’s misfiring can trigger fear while on the road, or prevent you from using your car entirely as a result. It can be a symptom of a bigger issue, so it’s important to understand just what might be causing your engine to misfire, and what you can do if you notice something’s wrong. In this guide, we’re digging into the mystery of misfiring, from the causes and symptoms, to how we can help you with your engine repairs to get your vehicle back on the road in no time.

Understanding Engine Misfires:

Engine misfiring can be a daunting thing to experience, and usually occurs when one or more of the cylinders in your engine fail to ignore the air-fuel mixture properly. This can be caused by several factors and the failure can usually lead to even further issues in your vehicle, whether it’s simply reduced fuel efficiency, or damage to crucial components in your engine. Knowing what is causing the misfiring can help resolve the issue as quickly as possible to protect your vehicle. Some of the most common causes of a misfiring engine include:

• Ignition System Issues – Issues within the ignition system such as faulty spark plugs, ignition coils, or spark plug wires can disrupt the spark needed for combustion and trigger a misfire.
• Fuel Delivery Problems – Clogged fuel injectors, a malfunctioning fuel pump, or a dirty fuel filter can disrupt the delivery of fuel into the system and affect the proper fuel-air mixture.
• Air Intake and Vacuum Leaks – Unmetered air entering the engine, often through vacuum leaks, can disturb the air-fuel ratio or allow contamination.
• Faulty Sensors – Malfunctioning sensors, such as the mass airflow sensor (MAF) or oxygen sensor, can impact fuel injection and combustion and lead to a misfire. 
• Compression Issues – Poor compression in one or more cylinders due to worn piston rings, cylinder head gasket leaks, or valve problems, can cause your engine to misfire.
• Exhaust System Problems – A clogged catalytic converter or exhaust restriction can disrupt engine performance and cause problems if left unchecked.

Recognising Symptoms of Engine Misfires:

If you’ve never experienced a misfire before, you may not even know what to look out for or if what you’re experiencing is a misfire at all. Recognising and understanding the ‘symptoms’ can help you determine what’s going on and the help you may need to resolve the issue. Common symptoms of a misfire include:

• Uneven or Rough Idling – If your vehicle has noticeable shaking or vibrating when the vehicle is at a standstill, this could be a sign that your engine is misfiring. The air/fuel mixture being disrupted may cause the engine to jump up and down, which causes a rough sensation.
• Loss of Acceleration Power – Misfiring can cause reduced engine power during acceleration or while driving uphill, which can be dangerous if not handled quickly.
• Increased Emissions – Due to the incomplete and disrupted combustion process, misfiring can cause higher levels of emissions and toxins to be pushed out into the air.
• Poor Fuel Efficiency – With decreased performance and poor air/fuel combinations, comes increased fuel consumption by your vehicle to cater for this loss. This means increased miles per gallon and a reduction in overall fuel efficiency.
• Check Engine Light – An illuminated check engine light often accompanies engine misfires, which gives you a clear sign that something needs to be looked at by a qualified mechanic, such as our team here at Service4Service.

What to Do When Your Engine Misfires

If your engine has been misfiring, there are several checks and diagnostics that need to take place to find the core of the problem. A warning light or poor performance might tell you that there’s a problem, but in order to fix the issue, you should seek the help of a mechanic to run a full diagnostic process. By knowing the cause, you can have the issue repaired quickly and get you back on the road as soon as possible. If your engine is misfiring, some of the checks that we can and will do include:

Checking the Causes Of Warning Lights

If your check engine light is on, the first thing we’ll do is run a diagnostic assessment using the vehicle’s onboard diagnostic (OBD-II) system. We look for error codes that will help direct us towards the problem so we can get to the very heart of the issue quickly and efficiently.

Inspect Spark Plugs and Ignition Components

Worn or damaged spark plugs and ignition components are common culprits of engine misfiring. When not at optimal performance or if burned out, a spark plug can fail to produce the spark needed to start combustion, ultimately triggering a misfire. We will replace any worn spark plugs or repair other ignition components as needed.

Examine the Fuel System

The fuel system is a crucial part of your vehicle but when things go wrong, it can often be the cause of misfiring or poor performance. We will check for clogged fuel injectors, inspect the fuel pump, and replace a dirty fuel filter if necessary.

Address Air Intake Issues

With poor quality or incorrect air intake, the air/fuel ratio can be compromised and ultimately lead to issues in the combustion process. If we suspect an air intake issue, we will inspect for vacuum leaks and ensure the system is free from obstructions and debris build-up.

Evaluate Sensors

Running the diagnostics for error codes will usually tell us if there is an issue relating to the sensors, but we will test and replace malfunctioning sensors affecting fuel delivery and combustion.

Compression Test

If there is a suspected issue with the cylinders themselves, a compression test can be used to assess their health and ultimately determine if they are in need of repair. 

No matter the cause of the issue, we will always provide you with a comprehensive cost estimation before starting any work. We will ask you to approve the cost before repairs are started, so you can rest assured that you will not be left with any unexpected bills at the end of the repair process.

While an engine misfire can be a cause for concern, understanding the potential causes and symptoms helps you stay on top of the issue and be proactive in the repair process. Regular maintenance, prompt attention to warning signs, and consulting with a qualified mechanic are key steps in ensuring your vehicle runs smoothly. Our team are on hand to help you with any repairs or maintenance you may need – simply get in touch with a member of our team for more information, today.