Ignition advancers and triggers spin on the end of the crankshaft and are designed and formed to create impulse signals that can be read or monitored by sensors. Each rotation creates a pattern that is then interpreted by the ignition system to precisely understand engine RPM. This allows the ignition system to adjust according to predefined maps. Triggers simply tell the motor when to fire each coil, advancers adjust the timing of this firing to optimize power delivery.