Q:

What are the signs of bad spark plugs?

A:

There are a variety of signs of bad spark plugs including difficulty with starting an engine, a rough idle and an increased consumption of gas. Other signs include an engine that has a sudden surge when driving and difficulty with acceleration when applying the gas.

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Spark plugs work by igniting the gasoline in a car's engine to keep it moving. In order to avoid issues, spark plugs should be cleaned and checked regularly. If the plugs get bad enough, the car will fail to run and start at all. Fortunately, spark plugs can go for approximately 30,000 miles before they need to be replaced.

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Related Questions

  • Q:

    How often should you change spark plugs?

    A:

    Spark plugs are replaced every 80,000 miles. Many vehicle manufactures claim their spark plugs can last up to 100,000 miles, but as the gap in the plugs widen, the chance of vehicle problems rises significantly. Some of these problems include bad gas mileage and reduced engine performance.

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  • Q:

    What causes oil to be on my spark plugs?

    A:

    Oil on spark plugs, also called oil fouling, is commonly caused by failing valve stem guides and bad stem seals. As pressure builds up in the crankcase, excessive oil enters the combustion chamber through worn-out piston rings or cylinder walls and forces its way to spark plugs. Oil fouling can also be caused by transmission fluid sucked through malfunctioning vacuum modulators or leaking lubricants from engine turbochargers.

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  • Q:

    When should you replace your spark plugs?

    A:

    Spark plugs need replacing when a car has trouble starting or accelerating or when the engine misfires, surges or produces a rough sound. Vehicle manufacturers offer recommendations for changing spark plugs that can be between every 30,000 miles and 100,000 miles, depending on the type of plugs.

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  • Q:

    Why do spark plugs foul?

    A:

    Worn or damaged valve guides, worn or damaged piston rings, rich fuel mixture and a leaky head gasket can all be causes of spark plugs fouling. An improperly performing ignition system might also be a cause for spark plug fouling.

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