ELECTRONIC SPARK ADVANCE CONTROL [SKYACTIV-G 2.0]

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Outline

• Controls ignition to the optimum timing according to engine operation conditions.

• Serviceability has been improved by eliminating the necessity of ignition timing adjustment.

• The PCM determines the engine operation conditions based on input signals from each sensor and blocks current to the ignition coils at the calculated ignition timing, causing the spark plugs to discharge (ignite) by the effect of electromagnetic mutual induction.

Block Diagram

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Operation

Ignition method

• The PCM excites the ignition coils employing either starting ignition or cycle estimated ignition according to engine operation conditions.

Ignition method

Ignition timing

Ignition coil energization period

Starting ignition

Determination based on engine coolant temperature

• Energization time to igniter (ignition coil energization time) is determined according to battery voltage

• Cylinder independent ignition

Cycle estimated ignition

Ignition at timing appropriate to engine operation conditions based on input signals

Ignition method	Ignition timing	Ignition coil energization period
Starting ignition	Determination based on engine coolant temperature	• Energization time to igniter (ignition coil energization time) is determined according to battery voltage • Cylinder independent ignition
Cycle estimated ignition	Ignition at timing appropriate to engine operation conditions based on input signals

Timing chart

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Determination of Ignition Timing

Division of control zones

• To perform optimum ignition control under all engine operation conditions, the PCM:

― Divides the engine control operation into each control zone according to the engine speed and accelerator pedal opening angle.

― Determines the ignition timing for each control zone.

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Control zone

Control condition

Ignition method

Engine start

Engine speed is less than 500 rpm

Engine starting

Idle zone

Accelerator pedal not depressed

(Cycle estimated ignition) (Determines ignition timing adding each correction to idle spark advance)

Normal zone

Engine operation except start and idling zones

(Cycle estimated ignition) (Determines ignition timing adding each correction to basic spark advance)

Control zone	Control condition	Ignition method
Engine start	Engine speed is less than 500 rpm	Engine starting
Idle zone	Accelerator pedal not depressed	(Cycle estimated ignition) (Determines ignition timing adding each correction to idle spark advance)
Normal zone	Engine operation except start and idling zones	(Cycle estimated ignition) (Determines ignition timing adding each correction to basic spark advance)

Ignition timing calculation method table

A: Ignition timing base, B: Correction for ignition timing

Contents		Calculation method or determination method for ignition timing, spark advance, and correction	Control zone
Contents
Starting ignition		Determination based on engine coolant temperature	A
Cycle estimated ignition	Idle spark advance	Set value according to target speed and charging efficiency^*		A
Cycle estimated ignition	Basic spark advance	Set value according to engine speed and charging efficiency^*			A
Correction	Engine coolant temperature spark advance correction	Purpose: Ensures combustion stability when engine coolant temperature is low According to engine coolant temperature • High charging efficiency^*, low engine coolant temperature→large correction		B	B
	Warm-up promotion spark retard correction	Purpose: Activates the catalytic converter earlier Approx. 50 s after engine start • According to engine coolant temperature→correction		B
	Feedback correction	Purpose: Ensures idling stability While idling (inhibited during test mode) • Large difference between actual engine speed and target engine speed→large correction • Small difference between actual engine speed and target engine speed→small correction		B
	Retard correction	Purpose: Reduces shift shock during down shifting According to torque reduction request signal from TCM and DSC HU/CM • Large torque reduction request during shifting→large correction			B
	Deceleration fuel cut recovery retard correction	Purpose: Reduces shock during recovery from deceleration fuel cut Recovery from deceleration fuel cut • Difference between turbine speed and engine speed is larger→large correction		B	B
	Acceleration spark retard correction	Purpose: Prevents knocking and shock during sudden acceleration Acceleration when charging efficiency^* volume increase (acceleration amount) is given value or more • Large acceleration amount→large correction			B
	Acceleration from standstill spark retard correction	Purpose: To prevent shock when the vehicle accelerates from a standstill When vehicle accelerates from a standstill • According to engine speed, throttle valve opening angle, accelerator, gear, clutch, engine coolant temperature and intake air temperature→correction			B
	Knocking spark retard correction	Purpose: Knocking suppression When knocking is detected while driving under a load • Large amount of knocking→large correction			B
	Valve timing correction	Purpose: Ensures combustion stability When phase difference changes due to electric variable valve timing control and variable valve timing control • Correction according to change in phase difference			B

* :Charging efficiency is the ratio of the actual amount of intake air to the maximum air charging amount (mass volume) of the cylinder. This value increases proportionately to the increase in engine load.