Newer engines typically use electronic ignition systems (ignition controlled by a computer). The computer has a timing map which is a table with engine speed on one axis and engine load on another axis. Timing advance values are inserted in this table. The computer will send a signal to the ignition coil at the indicated time in the timing map in order to spark the spark plug. Most computers from original equipment manufacturers (OEM) are not able to 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.
Peccavi, July 2009
