The ignition system supplies the spark that ignites the air/fuel mixture in the combustion chambers. For optimal performance and fuel mileage, and minimal emissions, the spark must be powerful and properly timed for all operating conditions. There are mechanical breaker point and electronic distributor ignition systems, distributorless ignition systems, and Coil-On-Plug (COP) systems, but no matter what you have we can supply you with replacement parts.
Spark plugs are the most commonly serviced parts in the ignition system. A spark plug consists of a center electrode inside an insulator and steel shell. A side electrode curves out from the bottom of the shell toward the center electrode. The shell is threaded, so the spark plug can be installed in the combustion chamber. When high voltage is sent by the ignition coil to the spark plug, a spark jumps the gap between the center and side electrodes, igniting the air/fuel mixture. However, a small amount of the electrodes wears every time the plug fires, eventually increasing the gap and requiring spark plug replacement.
The ignition system has a primary and a secondary circuit. The primary circuit includes the battery, ignition switch, a control module (switching device), and the primary winding of the ignition coil. The secondary circuit includes the secondary winding of the ignition coil, spark plugs, and on some vehicles a distributor and/or spark plug wires. The ignition coil transforms the 12 volts from the battery to 15,000-40,000 volts needed by the spark plugs.
Distributor ignitions have a single coil, electronic distributorless ignitions have a coil for each pair of cylinders, and COP systems have a coil for each spark plug. However, all are constructed in basically the same way. The primary winding has 100-200 turns of heavy wire wound around an iron core. The secondary winding has thousands of turns of very fine wire inside the primary winding. When current flows through the primary winding, a magnetic field is created. When the control module interrupts current flow, the magnetic field collapses, producing high voltage in the secondary winding.
Breaker point distributor ignition systems were the standard of the industry for decades, however the breaker points wore and required frequent maintenance. Electronic distributor ignitions were an advancement, but still suffered from distributor, cap and rotor wear. Waste spark ignition systems eliminate the distributor and instead use a coil for each pair of cylinders, however spark plug wires are still used. COP ignitions are the most sophisticated systems. The spark plug wires have been eliminated, along with the arcing and misfires that wire damage could cause, and ignition timing is electronically controlled.
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