Mazda 2004 RX-8, Особенности сервиса

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CONTROL SYSTEM
01–40–12
DRIVE-BY-WIRE CONTROL OPERATION
CHU014000140S12
Idle Speed Control
•
Controls the throttle valve opening angle so that it is close to the target idle speed calculated by the PCM.
•
The PCM calculates the target throttle opening angle by adding each type of correction to the basic duty value
which is the basis of the throttle valve opening angle, and then sends a duty signal to the throttle valve actuator.
The basic duty value is determined by the target engine speed.
•
Each type of correction is as follows.
Correction
Accelerator Control
•
Controls the throttle valve opening angle through control of the throttle valve actuator, according to the amount
of AP depression.
•
The PCM controls the throttle valve actuator so that the actual throttle valve opening angle is close to the target
throttle valve opening angle.
•
The final throttle valve opening angle is determined by the sum of the target throttle opening angle during idling
and the target throttle valve opening angle during regular driving.
•
The target throttle valve opening angle during regular driving is determined based on the transmission gear
position, the amount of AP depression and the engine speed. If the target throttle opening angle is at the fixed
value or less during regular driving, the PCM switches to idle speed control.
•
The PCM sets the throttle valve to the fully-closed position when the ignition switch is on or off and executes
the idle position learning function to learn the throttle valve position. Due to this, changes in the throttle valve
opening angle due to age deterioration are corrected.
•
When the ignition switch is off, a main relay on request is output and the fully-closed learning function is
executed. (See 01–40–10 MAIN RELAY CONTROL OPERATION.)
Correction Purpose Condition Amount of Correction
Water temperature
correction Corrects changes in engine friction
resistance based on changes in engine
temperature. Determines correction amount
based on ECT. Correction amount decreases
as ECT increases.
Correction at engine
start Prevents idle speed dropping off after
engine start. Directly after cranking and
engine-start. Correction amount increases
as ECT decreases.
Feedback correction Performs feedback control so that idle
speed is close to the target idle speed.
•
Executes feedback
conditions when all of the
following conditions are
met:
— Vehicle stopped
— AP fully closed
•
Correction amount
decreases when the idle
speed is higher than the
target idle speed.
•
Correction amount
increases when the idle
speed is lower than the
target idle speed.
Learning correction Corrects air flow amount changes from
changes in the engine due to aged
deterioration such as engine friction
resistance and air leakage from the
throttle valve. Determined by the amount of
feedback correction when
external load correction and
purge control stop. Learning correction executed
when upper or lower limit of
feedback correction exceeds
the fixed value.
Purge correction Increase in air from purge control is
subtracted from the target throttle
opening angle. Increases throttle valve
opening angle to prevent rotation
fluctuation from changes in air/fuel ratio
when purge concentration is high. Determined by the purge flow
amount and purge
concentration when purge
control is executed.
•
Correction amount
decreases as purge flow
amount increases.
•
Correction amount
increases as purge flow
concentration increases.
Load correction when
vehicle accelerates
from idle (MT) Prevents engine speed drop after
vehicle accelerates from idle. At acceleration from idle The amount of correction
increases as the idle speed
depression amount increases.
External load
correction
•
Prevents engine speed drop when
the A/C and electrical load are
operating.
•
Prevents engine speed revving
when the A/C and electrical load
are off.
•
When any of the following
signals are input:
— A/C amplifier (A/C
switch)
— Refrigerant pressure
switch (medium-
pressure switch)
— Generator current value
Correction amount increases
as external load increases.
Fast idle up
correction Rapidly activates the catalytic
converter after cold-engine start. Synchronizes fast idle
correction for electric spark
control. (See 01–40–28
ELECTRIC SPARK
ADVANCE CONTROL
OPERATION.) Correction amount increases
as the ignition timing retard for
the fast idling correction of the
ignition timing control
advances.