Mazda RX-8 2004 - Electric Spark Advance Control Operation; Ignition Method; Determination of Ignition Timing; Fixed Ignition

CONTROL SYSTEM
01–40–28
ELECTRIC SPARK ADVANCE CONTROL OPERATION
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Ignition Method
• The PCM controls fixed ignition and regular ignition according to the engine operation conditions.
Determination of Ignition Timing
Control Zone Divisions
• The PCM divides the full range of ignition control into control zones and determines the ignition timing from
each control zone according to engine speed and throttle valve opening angle to perform optimum ignition
control at the full range of engine operating conditions.
Fixed Ignition
• At engine start, fixed ignition is performed at BTDC 5° until the engine speed reaches 500 rpm or more, due to
ignition timing control difficulty from changes such as low battery positive voltage from start operation and
fluctuations in engine speed.
Regular Ignition
• The PCM determines the optimum final ignition timing, adding each type of spark advance correction to the
base spark advance, ECT spark advance correction, and the IAT spark advance correction.
Basic spark advance
• The basic spark advance becomes the basis for the ignition timing control.
• The basic spark advance amount is determined by the engine speed, charging efficiency and the ECT.
Ignition Method Ignition timing
Fixed ignition Ignition fixed at BTDC 5°
Regular ignition Appropriate ignition for engine operation conditions based on input signals.
BTDC 5°
BTDC 5°
EXHAUST
EXHAUST
EXHAUST
INTAKE
INTAKE
INTAKE
COMPRESSION
COMBUSTION
COMBUSTION
COMBUSTION
COMPRESSION
COMPRESSION
FRONT ROTOR
REAR ROTOR
ECCENTRIC
SHAFT POSITION
SENSOR SIGNAL
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OPEN
CLOSE
REGULAR ZONE
REGULAR
IGNITION
ENGINE SPEED
HIGH
THROTTLE
VALVE
POSITION
IDLE ZONE
START ZONE
FIXED
IGNITION
LOW
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Ignition
Method
Zone Condition Ignition timing
Fixed
ignition
Start zone
• Engine speed 500 rpm or less
• When MAF sensor has a malfunction.
Fixed ignition
Regular
ignition
Idle zone When the AP is fully closed (during idle).
Determined by addition of each type of
correction to the basic spark advance.
Regular zone
During engine operation other than start zone
and idle zone
Determined by addition of each type of
correction to the basic spark advance.