Do-It-Yourself High Performance Car Mods

Spark Timing

Ignition systems come in two main categories: distributors and multiple coils. Distributors may control the timing with a mechanical system mounted in the distributor or by an external computer, while systems with multiple coils require computer control. Multiple coil systems include several different designs, such as wasted spark systems that send a spark to two cylinders at once using a coil with two terminals. This spark happens in the exhaust stroke, so the second spark does nothing. Another sort is known as coil-on-plug, where the coils attach directly to the spark plugs with no wires.

When it comes to adjusting the spark timing, computer-controlled systems all work in much the same way. A computer takes a signal from a sensor ...