Yamaha WR45OFR service manual MAP-CONTROLLED CDI Unit, Function of Component

MAP-CONTROLLED CDI UNIT

MAP-CONTROLLED CDI UNIT

A map-controlled, CDI ignition system is used in the WR450F.

ELEC

–+

The microcomputer in the CDI unit detects the engine speed and throttle position, thus determining the optimum ignition timing through the entire operating range. In this way, quick throttle response can be achieved according to various riding conditions.

Ignition coil

Throttle position sensor

CDI unit

Pickup coil AC magneto rotor

■Function of Component

Component	Function
TPS	Detects throttle valve opening and inputs it into the computer in the
(throttle position sensor)	CDI unit as a throttle opening signal.
Pickup coil	Detects signal rotor revolutions and inputs them into the computer in
	the CDI unit as engine revolution signals.
CDI unit	The signals of the TPS and pickup coil sensor are analyzed by the
	computer in the CDI unit, which then adjusts ignition timing for the
	operation requirements.

6

■Principal of 3-Dimensional Control Conventionally, ignition timing was controlled only by engine revolutions (2-dimensional control). However, ignition timing needs advancement also by engine load. Thus, accurate ignition timing can be determined by adding throttle opening to deter- mine ignition timing (3-dimensional control).

Ignition timing

Throttle opening

Revolutions

6 - 2

3-D Image Map of Ignition Timing (different from actual characteristics)