DRIVE-BY-WIRE CONTROL OPERATION [MZR 2.0 DISI]

id0140j3170600

Idle Speed Control

• In order to ensure idling stability, the PCM controls the throttle valve and sets an optimal throttle valve opening angle based on the engine operating conditions.

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

A/C load correction

Prevents decrease in idle speed due to A/C operation.

A/C is operating.

A/C operation time→correction

Electrical load correction

Prevents decrease in idle speed due to electrical load operation.

Idle speed during electrical load operation and under any condition during driving

High electrical load→large correction

D-range correction

Prevents decrease in idle speed due to shifting into D-range.

D-range signal is input.

Shifted to D range→correction

Dashpot correction

Prevents decrease in idle speed due to insufficient intake air amount during deceleration.

Decelerated

High engine speed→large correction

Correction at engine start

Prevents decrease in idle speed after engine start.

After cranking and engine start

Low ECT→large correction

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

Feedback correction A

Sets idle speed to target engine speed.

Idle speed during idling (vehicle is stopped) is over or under the target engine speed (except during test mode).

Actual idle speed

Target engine speed or less→volume increase correction

Target engine speed or more→volume decrease correction

Feedback correction B

Sets to the target engine speed when the idle speed has decreased in the range not corrected by feedback correction A, and prevents a decrease in idle speed.

During deceleration at fully closed throttle, the engine speed is the target engine speed or more and when the feedback correction A is not performed (except during test mode).

Large difference between actual idle speed and target engine speed→large correction

Learning correction

Stores intake air volume changes based on differences between engines and changes due to aged deterioration, and feedback.

During feedback correction A when ECT is 85 °C {185 °F} or more.

During idling→average value of feedback correction A

Correction	Target	Conditions	Correction amount
A/C load correction	Prevents decrease in idle speed due to A/C operation.	A/C is operating.	A/C operation time→correction
Electrical load correction	Prevents decrease in idle speed due to electrical load operation.	Idle speed during electrical load operation and under any condition during driving	High electrical load→large correction
D-range correction	Prevents decrease in idle speed due to shifting into D-range.	D-range signal is input.	Shifted to D range→correction
Dashpot correction	Prevents decrease in idle speed due to insufficient intake air amount during deceleration.	Decelerated	High engine speed→large correction
Correction at engine start	Prevents decrease in idle speed after engine start.	After cranking and engine start	Low ECT→large correction
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
Feedback correction A	Sets idle speed to target engine speed.	Idle speed during idling (vehicle is stopped) is over or under the target engine speed (except during test mode).	Actual idle speed Target engine speed or less→volume increase correction Target engine speed or more→volume decrease correction
Feedback correction B	Sets to the target engine speed when the idle speed has decreased in the range not corrected by feedback correction A, and prevents a decrease in idle speed.	During deceleration at fully closed throttle, the engine speed is the target engine speed or more and when the feedback correction A is not performed (except during test mode).	Large difference between actual idle speed and target engine speed→large correction
Learning correction	Stores intake air volume changes based on differences between engines and changes due to aged deterioration, and feedback.	During feedback correction A when ECT is 85 °C {185 °F} or more.	During idling→average value of feedback correction A

Accelerator Control

• Controls the throttle valve opening angle through control of the throttle valve actuator, according to the amount of Accelerator pedal 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 Accelerator pedal 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.

Traction Control

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

Cruise Control (With Cruise Control System)

• Calculates the throttle valve opening angle based on the deviation of the actual vehicle speed from the set vehicle speed which was set with the cruise control switch and the throttle valve actuator.

• The PCM controls the actual vehicle speed so that it is close to the set vehicle speed.

• The cruise control includes the cruise control operation condition and the cruise control stop condition.

Cruise control operation condition

• When all of the following conditions are met, execution of the cruise control system is enabled (cruise control standby status).

― ON switch: ON

― Vehicle speed: Exceeds 25 km/h {16 mph}

Cruise control stop condition

• When any of the following conditions are met even while in cruise control, the PCM stops the cruise control and clears the set vehicle speed.

― Ignition: OFF

― OFF switch: ON

― Cruise control related DTCs (P0571:00, P0579:00, P0581:00) detected

• When any of the following conditions are met even while in cruise control, the PCM stops the cruise control while storing the set vehicle speed.

― CANCEL switch: ON

― Vehicle speed: Less than 20.5 km/h {12.7 mph}

― Brake switch: ON (brake pedal depressed)

― The actual vehicle speed is 15 km/h {9.3 mph} or more lower than the set vehicle speed during cruise control (ascending).

― CPP switch: ON (clutch pedal depressed)

― Neutral switch: ON (neutral position)

Cruise control function

• The cruise control includes accelerating, coasting, resume, tap-down, tap-up and downshift functions.

Function List

Function	Contents
Accelerating	• When the SET+ switch is continuously pressed, the PCM gradually increases the set vehicle speed.
Coasting	• When the SET- switch is continuously pressed, the PCM gradually decreases the set vehicle speed.
Resume	• When the RESUME switch signal is input to the PCM during regular driving (cruise control is stopped) and the previously set vehicle speed is stored in the PCM, the PCM sets the set vehicle speed to the previously set vehicle speed and begins control.
Tap down	• When all of the following conditions are met while driving in cruise control, the PCM decreases the set vehicle speed by 1 km/h {0.6 mph}. ― During cruise control ― The SET- switch switches from off to on ― When actual vehicle speed is lower (set vehicle speed +2 km/h {+1 mph})
Tap-up	• When all of the following conditions are met, the PCM increases the set vehicle speed by 1 km/h {0.6 mph}. ― During cruise control ― The SET+ switch switches from off to on ― When actual vehicle speed is lower (set vehicle speed +2 km/h {+1 mph})

Excess Engine Speed Control

• If the engine reaches a high engine speed, the following controls are performed to protect the engine:

1. To alert the driver that the engine speed has reached a high engine speed, the opening and closing of the throttle valve are repeated at regular intervals.

2. The engine speed stabilizes at a lower speed than the excessive speed zone.

3. If the engine speed reaches a high engine speed even if the above procedures are performed, a forced shift-up is performed to lower the engine speed. (ATX)

Excess Vehicle Speed control

• If the vehicle reaches a high speed, the throttle valve is closed to keep the vehicle speed below the speed limit.

Brake Override System (From GH1***-442043)

Operation of brake override system

• In the event of any malfunction in the accelerator system, the vehicle is equipped with a sub-system that prioritizes the brake operation over the accelerator pedal operation. Specifically, the sub-system functions to close throttle valve when the brake pedal is depressed while the accelerator pedal is depressed to safely decelerate the vehicle to a full stop.

Brake override operation conditions

•  If either one of the following conditions is met with the brake pedal depressed for 1 s or more while the accelerator pedal is depressed, the PCM adjusts the throttle valve opening angle so that the engine speed is the specification^*.

While driving vehicle

―  Accelerator pedal opening angle: 5% or more from fully-closed

―  Vehicle speed: 10 km/h {6.2 mph} or more

―  In gear

―  Engine speed: 1,150 rpm or more

While vehicle stopped

―  Accelerator pedal opening angle: 5% or more from fully-closed

―  Shift lever position: neutral (MTX)

―  Selector lever position: N position (ATX)

―  Engine speed: 1,150 rpm or more

End brake override operation

•  To return the throttle to normal operation, the following conditions must be met.

―  Accelerator pedal is not depressed

―  Brake pedal is not depressed

Note

•  Cycling the key off and back on will also end brake override operation.

* :For MTX vehicles, engine speed is 1,200 rpm when in neutral, and 1,100 rpm when not in neutral. For ATX vehicles, engine speed is 1,200 rpm when in N position, and 1,100 rpm when in D position.

Disabling of brake override system

• If the servicing procedure requiring the brake pedal and the accelerator pedal to be depressed together, operation of the brake override system can be prevented, if necessary.

Disable brake override operation conditions

•  If the following conditions are met for 10 s within 30 s after switching the ignition ON (engine off), the brake override system is disabled until the activate brake override operation conditions are met.

―  Vehicle speed: 0 km/h {0 mph}

―  Accelerator pedal fully depressed

―  Brake pedal depressed

Activate brake override operation conditions

•  Cycling the key off and back on will activate the brake override operation conditions.

Brake warning light illumination request (vehicles without malfunction warning light)

• If the following condition is met, the PCM sends the brake warning light illumination request signal to the instrument cluster. The brake warning light illuminates to alert the driver that there is a malfunction in the brake system.

― Brake switch No. 1 or 2 malfunction is detected

Malfunction warning light illumination request (vehicles with malfunction warning light)

• If the following condition is met, the PCM sends the malfunction warning light illumination request signal to the instrument cluster. The malfunction warning light illuminates to alert the driver that there is a malfunction in the brake system.

― Brake switch No. 1 or 2 malfunction is detected

Disable brake override operation conditions	• If the following conditions are met for 10 s within 30 s after switching the ignition ON (engine off), the brake override system is disabled until the activate brake override operation conditions are met. ― Vehicle speed: 0 km/h {0 mph} ― Accelerator pedal fully depressed ― Brake pedal depressed
Activate brake override operation conditions	• Cycling the key off and back on will activate the brake override operation conditions.