Fouled or failing spark plugs, damaged spark plug wires, clogged or bad fuel injectors, a weak fuel pump or plugged fuel filter, or a cracked distributor cap are some causes of car engine cylinder misfires. All of these items are relatively easy to diagnose at home for garage mechanics. Complex issues such as vacuum leaks or improper compression may require professional service. Error codes from the car's on-board diagnostic computer usually identify cylinder misfires on newer vehicles.
Problems generated by the ignition and firing system are some of the most common causes of cylinder misfires. All of the spark plugs need to be removed, cleaned thoroughly and replaced if they look burned or scorched badly. Remove the distributor cap, and clean all of the connections. The spark plug wires should have no cracks or damaged areas to function properly.
A lean misfire can occur when not enough fuel is getting into the cylinders. Adding a fuel injector cleaner into the car's gasoline tank according to the instructions may fix the problem and help with a plugged fuel filter. To eliminate the fuel system, use a fuel pressure gauge to diagnose a lean fuel mixture problem. If the pressure gauge detects not enough fuel coming from the gas tank, then this calls for a fuel pump and air filter replacement.