ELECTRONIC SPARK ADVANCE OPERATION [L8, LF, L3]

id0140a5175000

Ignition method

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

Ignition method

Ignition timing

Ignition coil energization period

Fixed ignition
Fixed at BTDC 10°
Fixed period at BTDC 10° to end of energization
Cycle estimated ignition
Ignition at timing appropriate to engine operation conditions based on input signals
• Energization time (ignition coil energization time) to igniter is determined according to battery voltage
• Cylinder independent ignition

1
CKP sensor signal
2
CMP sensor signal
3
Cylinder number
4
Intake air
5
Exhaust air
6
Expansion
7
Compression
8
Ignition coil energization allowance period

Determination of Ignition Timing

Division of control zones

• The PCM divides the engine control operations into each control zone according to the engine speed and throttle valve opening angle to determine the ignition timing by each of the control zones to perform optimum ignition control under all engine operation conditions.

1
Throttle valve position
2
Engine speed
3
Start zone
4
Regular zone
5
Idle zone
6
Open
7
Closed
8
Low
9
High

Control zone

Control condition

Ignition method

Start zone
Engine speed is 500 rpm or less.
When mass airflow sensor is damaged.
Fixed ignition
Idle zone
Fully-closed throttle valve when engine speed is the target idle speed + 1,750 rpm or less
Determines ignition timing adding each correction to the idle spark advance
Cycle estimated zone
Engine operation except start zone and idle zone
Determines ignition timing adding each correction to the 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, advance value and correction

Control zone

Fixed ignition

Fixed at BTDC approx. 10° CA
A
 
 

Cycle estimated ignition

Idle spark advance

Set value according to target speed and charging efficiency*
 
A
 

Basic spark advance

Set value according to engine speed and charging efficiency*
 
 
A
Correction
Engine coolant temperature advance correction
Purpose: Ensures combustion stability when engine coolant temperature is low
Except during idling
• 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
During 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
 
EGR correction
Purpose: Prevents deviation of required ignition timing during EGR gas feed
When EGR valve position is the specified value or more except during EGR valve initialization
• According to engine speed and charging efficiency*→correction
 
 
B
Deceleration fuel cut recovery retard correction
Purpose: Reduces shock after recovery from deceleration fuel cut and during re-acceleration while in deceleration fuel cut
Re-acceleration after recovery from deceleration fuel cut and while in deceleration fuel cut
• Low engine coolant temperature→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 specified value or more
• High acceleration amount→high retard
 
 
B
Standing start spark retard correction
Purpose: Prevents shock when vehicle accelerates from a standing start
When vehicle accelerates from a standing start
• According to engine speed, throttle valve opening angle, engine coolant temperature and intake air temperature→correction
 
 
B
Knocking spark retard correction
Purpose: Knocking suppression
When knocking is detected while driving under high load
• Large amount of knocking→large correction
 
 
B
* :
Charging efficiency is ratio of actual intake air amount to maximum air charging amount (mass volume) of cylinder. This value increases proportionately to the increase in engine load.

Ignition inhibition condition

• When receiving an engine stop request signal from the immobilizer system, the PCM force-stops control of ignition coils. As a result, the engine does not start.