Q:

What causes ignition coils to go bad?

A:

Quick Answer

The top reason ignition coils fail is bad spark plugs or plug wires. Another potential cause is heat and vibration, which can damage the ignition coil's windings and insulation. If an engine is experiencing repeated coil failures, the underlying cause may be resistance from worn spark plugs or excessive spark plug gap. In rare cases, the failure may be due to a lean fuel condition caused by leaky valves.

Know More

Full Answer

An automobile's ignition coil provides the high voltage needed by the ignition system to fire the spark plugs. It increases the ignition system's primary voltage from 12 volts up to thousands of volts. If a spark plug or plug wire is open or has excessive resistance, the ignition coil's output voltage can shoot higher and burns through the coil's internal insulation, causing a short. This is most likely to occur when output exceeds 35,000 volts.

When a coil failure occurs, the coil's voltage output drops, and the engine may not start or may misfire badly when under load. The misfire may also jump from cylinder to cylinder. A car owner suspecting damage to the ignition coil should measure the coil's primary and secondary resistance with an ohmmeter. If either is out of specifications, the coil needs to be replaced.

Learn More
Sources:

Related Questions

  • Q:

    What does an ignition coil do?

    A:

    An ignition coil is a coil in a car's ignition system that carries the 6 or 12 volts from the battery to the many volts used to spark the spark plugs in the ignition. An ignition coil is also called a spark coil, and is classified as an induction coil. All induction coils are electronic transformers that transform low-voltage pulses from the DC supply into higher voltage currents needed to spark machine engines.

    Full Answer >
  • Q:

    How is an ignition coil tested?

    A:

    Although there are a number of suggested tests for the ignition coil while it is still attached to a car, the only accurate way of testing a coil is on a bench using a multimeter in the resistance setting. The ignition coil has two coils of wires, called windings. The meter quickly displays if either winding is bad.

    Full Answer >
  • Q:

    What is ignition temperature?

    A:

    The ignition temperature of a given substance is the measure of the minimum temperature at which the substance ignites, without the presence of an external spark or flame. Because of the fact that the material auto-ignites at this temperature range, it is also referred to as the substance's auto-ignition temperature.

    Full Answer >
  • Q:

    How to wire an ignition switch?

    A:

    Wiring an ignition switch involves locating the ignition switch, identifying the pins, disconnecting the negative battery cable, connecting the lead wire to the ACC terminal, connecting the relay wire to the ST terminal, connecting the ignition wire to the IGN terminal and reconnecting the negative battery cable. Disconnecting the cable exposes the terminals and enables the power lead wires to be connected to the terminal of the switch.

    Full Answer >

Explore