Computer-controlled Ignition Systems
Newer engines typically use computerized ignition systems. The computer has a timing map (lookup table) with spark advance values for all combinations of engine speed and engine load. The computer will send a signal to the ignition coil at the indicated time in the timing map in order to fire the spark plug. Most computers from original equipment manufacturers (OEM) cannot be modified so changing the timing advance curve is not possible. Overall timing changes are still possible, depending on the engine design. Aftermarket engine control units allow the tuner to make changes to the timing map. This allows the timing to be advanced or retarded based on various engine applications.
Read more about this topic: Ignition Timing
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