Q:

What causes an engine cylinder misfire?

A:

Quick Answer

Primary causes of engine cylinder misfires include loss of compression, an unbalanced air or fuel ratio, a loss of spark and a malfunctioning fuel injector. The misfire occurs as a result of a partial combustion process occurring inside one of the cylinders. When incomplete combustion occurs, the driver experiences a jerking action within the engine.

Continue Reading
What causes an engine cylinder misfire?
Credit: Car Culture Car Culture Collection Getty Images

Full Answer

The ignition system is where most engine misfires develop. This system consists of the spark plugs, distributor cap, ignition cables, rotor and ignition coil. As the engine components experience wear over time, they lose the ability to transfer the spark required for combustion. As the wear increases, the engine misfires intensify. A lean misfire occurs as a result of an imbalanced air or fuel ratio. This misfire occurs when there is too much air or too little fuel. Causes of a lean misfire include an open EGR valve, a weak fuel pump, a leaking intake manifold gasket, a clogged fuel filter, a failing fuel pump and a malfunctioning mass airflow sensor. Causes of engine misfires can also be mechanical, and these types of misfires occur as a result of worn piston rings, defective fuel injectors, leaking head gaskets, broken rocker arms and worn valves and cylinder walls. A mechanical misfire is identified by a "thumping" feel inside the engine that is present regardless of engine speed.

Learn more about Car Parts & Maintenance

Related Questions

  • Q:

    How does a car's fuel system work?

    A:

    A car's fuel system stores fuel and supplies it to the engine by mixing the fuel with air, in addition to atomizing and vaporizing it, before it's compressed in the engine cylinder and ignited to produce energy. Different cars utilize different kinds of fuel systems, but fuel systems always supply fuel to the combustion chamber and regulate the amount of fuel supplied in relation to the amount of air.

    Full Answer >
  • Q:

    What are symptoms of a bad oxygen sensor?

    A:

    The typical signs of a faulty oxygen sensor include increased exhaust emissions due to poor air fuel mixture, engine hesitations, engine misfires, stalling, rough idling and increased fuel consumption. The oxygen sensor is a crucial component of a vehicle's electronic fuel injection and emission system, and it relays information to an on-board engine management computer that regulates fuel delivery to the engine.

    Full Answer >
  • Q:

    What are some ways to diagnose an engine misfire?

    A:

    The best way to diagnose an engine misfire is by testing each of the components that most commonly cause misfires: spark plugs, plug wires, the coils and the fuel-delivery system. More serious issues could involve the pistons, rods and crank bearings.

    Full Answer >
    Filed Under:
  • Q:

    What are the symptoms of a bad MAF sensor?

    A:

    The mass air flow sensor measures the amount of air entering the engine to determine how much more gasoline is needed in each cylinder to help maintain the proper fuel air ratio. A bad MAF sensor results in a wide variety of problems with the engine.

    Full Answer >
    Filed Under:

Explore