If your vehicle is showing engine misfires, sputters, or sounds like it's skipping a beat, here are the most likely causes and the parts you'll need to fix each one.
Spark plugs wear out over time, creating a weak spark that fails to ignite the fuel mixture properly. If recently replaced, incorrect spark plug gap, cracked porcelain from over-tightening, or loose plugs are very common installation errors.
Ignition coils and wires degrade from engine heat, leading to voltage arcing away from the spark plug. Leaving a coil connector unplugged, failing to seat the boot fully, or crossing spark plug wires are frequent mistakes after engine work.
Cracked hoses or failing gaskets allow extra, unmeasured air into the engine, leaning out the air-fuel mixture and causing a misfire (especially at idle). Hoses are frequently knocked loose or forgotten during routine under-hood maintenance.
A dirty or failing fuel injector will not spray the correct volume or pattern of fuel into the cylinder. This starves the cylinder of fuel, resulting in a lean misfire.
A dirty mass air flow sensor or a sluggish oxygen sensor can cause the engine computer to calculate the wrong air-fuel mixture, leading to engine-wide sputtering and hesitation.
A blown head gasket, burnt exhaust valve, or broken piston rings cause a loss of cylinder compression. This results in a permanent, severe misfire that will not be fixed by replacing spark or fuel components.