Ignition Timing: Function

At engine start up, the ECM sets ignition timing dependent on ECT information and starting rev/min from the CKP. As the running characteristics of the engine change, the ignition timing changes. The ECM compares the CKP signal to stored values in its memory, and if necessary advances or retards the spark via the ignition coils.

Ignition timing is used by the ECM for knock control.