DRIVE-BY-WIRE CONTROL OPERATION[L3]

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Idle Speed Control

Target throttle valve opening angle determination

•  The PCM calculates the intake airflow amount required to provide idling stability (IAC target airflow amount), and according to that, determines the target throttle valve opening angle.

•  When the engine is cranking, the PCM sets the IAC target airflow amount according to the engine coolant temperature, and opens the throttle valve to that set value.

IAC target airflow amount

•  The IAC target airflow amount is calculated by the PCM by subtracting the estimated value for the intake airflow amount which does not pass through the throttle valve from the calculated intake airflow amount required for idling stability (required volume weight).

Required volumetric airflow amount

―  The required volumetric airflow amount is calculated from the target charging efficiency as corrected by the changes in intake airflow amount (due to the difference in vacuum pressure in the areas before and after the throttle valve) and in intake airflow density (which changes according to intake airflow temperature change).

Target charging efficiency

―  The target charging efficiency is the charging efficiency* required to match engine operating conditions.

―  The target charging efficiency is calculated by adding all necessary corrections matching engine operating conditions to the basic charging efficiency as determined according to engine coolant temperature.

*  :Charging efficiency is the ratio of the actual intake airflow amount over the maximum amount of airflow (mass) which can fill a cylinder. This figure grows larger in proportion to the increase in engine load.

Correction	Target	Conditions	Correction amount
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.	Direct 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.
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.	Correction amount increases as the ignition timing retard for the fast idling correction of the ignition timing control advances.
Hot engine restart correction	Prevents decrease in idle speed from hot engine restart.	Just after cranking and engine start when the ECT is 60 °C {140 °F} or more the IAT is 40 °C {104 °F} or more	High intake airflow temperature→large correction
Dashpot correction	Prevents decrease in idle speed due to insufficient intake air amount during deceleration.	Decelerated	Low idle speed when shifted to D range→large correction

Target idle speed

•  The target idle speed for various engine operation conditions are as follows:

Standard

Load status		Idle speed (rpm) Neutral position
No load		650—750
Electrical loads on		650—750
P/S operating		650—750
A/C on		650—750

Accelerator Control

•  Feedback control has been adopted to the throttle actuator and it is monitored by the TP sensor so that it reaches the target throttle opening angle.

Target throttle opening angle

•  Throttle opening angle according to the engine speed and target charging efficiency table has been set.

Target charging efficiency table

•  This table has been created by assuming a target charging efficiency according to the engine speed and virtual accelerator opening angle.

Virtual accelerator opening angle

•  The virtual accelerator opening angle has been set according to the gear position, vehicle speed, accelerator opening angle, and accelerator opening change rate to improve driveability.

Traction Control

•  The PCM calculates the target throttle valve opening angle by the torque up/down request signal from the DSC HU/CM and TCM and the engine speed.