Spark advance

SPARK ADVANCE

(Continued)

The ECU can compute, thanks to a map saved in its memory, spark advance (for the cylinder in combustion phase), according to the following:

• engine ratio
• absolute pressure in intake manifold .

In the following conditions:

• idling speed
• full load

the ECU uses two specific tables according to rpm only.

The ECU corrects spark advance mainly on the basis of the following:

• engine coolant temperature
• throttle position.

The information processed by the ECU to pilot the ignition coils is received as electric signals transmitted from the following:

• throttle position potentiometer, intake air temperature and absolute pressure sensor (for exact quantity of intake air).

The throttle position potentiometer, moreover, detects minimum, partial and full load conditions.

• the rev sensor, which generates an alternating single phase signal indicating the engine revolution frequency and which piston is in TDC

IDLING CONTROL - MANAGEMENT

The ECU controls engine idling by means of the constant idling actuator when the throttle is closed and electric devices on (e.g. conditioner compressor).

The constant idling actuator is located directly onto the throttle and according to the commands received from the ECU opens the throttle by-pass. This ensures that idling ratio is as constant as possible, regardless of the engine load (electric, mechanic, hydraulic).