Why Is My Car Misfiring? Causes, Symptoms, and How to Fix It

Does your car feel jerky, lose power, or sound like it’s struggling when accelerating? These are all signs of a misfire — when one or more cylinders in your engine aren’t firing properly.

At Peers Auto Spares, we help South African drivers fix misfires by supplying the right spark plugs, filters, and other essential engine parts. This post explains why misfires happen and how you can stop them.

🔧 What Is an Engine Misfire?

An engine misfire occurs when the air-fuel mixture in one or more cylinders fails to ignite at the right time. This disrupts the smooth operation of the engine and causes:

  • Rough idling
  • Jerking when accelerating
  • Poor fuel economy
  • Loss of power
  • A “check engine” light

🚗 Common Causes of a Misfire

1. Worn or Faulty Spark Plugs

The most common cause of a misfire is old or damaged spark plugs. Spark plugs create the ignition needed to fire each cylinder. If they’re fouled or worn, they may spark weakly — or not at all.

Symptoms:

  • Engine stuttering
  • Loss of acceleration
  • Hard starting

🧰 Replace your spark plugs regularly to keep your engine firing cleanly and efficiently.

2. Clogged Fuel Injectors or Fuel Filter

Fuel injectors spray fuel into the engine. If they get blocked, the affected cylinder won’t get enough fuel, causing a misfire. Similarly, a clogged fuel filter can restrict fuel flow.

Look for:

  • Engine sputtering
  • Rough idle
  • Poor throttle response

🔧 Keep your fuel clean with a new fuel filter — available for all major brands at Peers Auto Spares.

3. Air Intake Problems

The engine needs the right mix of air and fuel. A dirty or clogged air filter can reduce airflow, disrupting combustion and causing misfiring — especially during acceleration.

🛒 Order air filters to restore airflow and prevent long-term engine damage.

4. Ignition Coil or Plug Wire Failure

In cars with coil-on-plug systems, a bad ignition coil can prevent spark from reaching the spark plug. Older cars may have faulty plug wires that stop spark from transferring properly.

Clues:

  • Misfire under load
  • Engine light with cylinder fault codes
  • Vibration at idle

5. Vacuum Leak or Intake Gasket Issue

An air leak in the intake system can cause uneven combustion and lead to cylinder misfires.

Listen for:

  • Hissing noise
  • Engine hunting (revving up and down)
  • Engine light on

6. Low Compression or Mechanical Problems

Less common but serious: if a cylinder has low compression due to a worn valve, piston ring, or head gasket, it may misfire continuously. This usually needs a professional repair.

🔍 How to Identify Which Cylinder Is Misfiring

Modern cars store this info in the onboard computer. An OBD2 scanner can tell you exactly which cylinder is misfiring (e.g., “Cylinder 3 Misfire”).

From there, you can:

  • Swap spark plugs or coils between cylinders
  • See if the misfire moves
  • Replace the failing part

🧰 At Peers Auto Spares, we can help you choose the correct plugs, coils, and filters for your car — just send us your registration or VIN.

🔄 Parts That May Need Replacing

  • ✅ Spark plugs
  • ✅ Fuel filter
  • ✅ Air filter
  • ✅ Ignition coils or plug wires
  • ✅ Fuel injectors
  • ✅ Gaskets or hoses (if leaking)

🔧 Browse all engine service parts — we stock trusted brands at affordable prices.

🛠️ How to Prevent Engine Misfires

  • Service your car regularly
  • Change spark plugs as recommended
  • Keep filters clean
  • Use good-quality fuel
  • Listen for early signs like rough idle or poor acceleration

✅ Final Thoughts

A car that misfires isn’t just annoying — it can damage your engine and reduce fuel efficiency. The good news? Most misfires are caused by affordable, easy-to-replace parts.

At Peers Auto Spares, we offer:

  • High-quality spark plugs, filters, and ignition parts
  • Fast delivery across South Africa
  • Expert support to help you choose the right fit

🚗 Visit our online store and get your engine running smoothly again.

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