Common Causes of Car Engine Misfires and How to Fix Them

Engine misfires can annoy and worry car owners. A misfiring cylinder is not firing properly. It can produce rough idle, poor acceleration, worse fuel efficiency, and increased emissions. Engine misfire causes and treatments are essential for vehicle performance and longevity.

Spark Plug Issues

Combustion occurs when spark plugs ignite engine cylinder air-fuel mixtures. Poor sparks might result from polluted, worn, or damaged plugs. Cylinders may fail. Check and replace spark plugs every 30,000 to 100,000 miles, depending on type, to avoid fires. If misfires occur, check and replace spark plugs.

Ignition Coil Problems

An ignition coil boosts battery voltage to spark the spark plug. A bad ignition coil can cause misfires under load or at high RPMs. A broken ignition coil causes engine stalling, performance loss, and starting issues. Repair engine operation by testing and replacing ignition coils. A bad coil is easier to locate and replace in vehicles with coils for each cylinder. For professional help, consider seeking Auto Repair Services in Sioux Falls, SD to ensure proper diagnosis and repair.

Fuel Delivery Issues

Engine performance demands gasoline. Fuel pump failure or clogged injectors can cause air-fuel imbalance and misfires. Slow acceleration, harsh idling, and poor fuel economy result from gasoline distribution issues. Fuel injector cleaners or professionals can remove minor obstructions. Replace the fuel pump if it fails to fuel the engine.

Vacuum Leaks

Air entering the engine unmetered causes vacuum leaks and leanness. Broken hoses, gaskets, and intake manifolds leak vacuum. High idle, engine bay hissing, and sluggish acceleration indicate a vacuum leak. Repairing vacuum leaks can rectify misfires and boost engine performance. Smoke machines and visual checks detect leaks.

Compression Loss

Cylinders losing compression can cause engine misfires. Piston rings, cylinder walls, and valves can wear out. Compression testing cylinder pressure can identify this issue. Engine rebuilds or valve replacements may be needed to correct compression loss. Correct oil changes and maintenance can avoid these issues.

Malfunctioning EGR

To reduce nitrogen oxide emissions, EGR recycles exhaust gases into engine cylinders. A malfunctioning EGR valve can inject extra exhaust gas, causing misfires. Rough idling, fuel economy loss, and emissions result from EGR issues. Cleaning or replacing the EGR valve frequently fixes these issues. EGR system functionality affects emissions and performance.

Oxygen Sensor Failures

Oxygen sensors measure exhaust gas oxygen and feed the ECU to adjust air-fuel mixture. An incorrect oxygen sensor can cause misfires and rich or lean mixes. Poor fuel economy, hard idling, and a bright check engine light are indicators. Replace faulty oxygen sensors to improve engine performance and fulfil pollution limits. Test sensors routinely to avoid long-term issues.


Simple spark plug issues to serious mechanical failures can cause engine misfires. Understanding common causes and taking preventative measures can boost engine performance and vehicle longevity. Engine efficiency and reliability depend on regular maintenance, rapid repairs, and quality parts.