i-stop CONTROL [SKYACTIV-G 2.5T]

id0140h0008900


Outline

•  When the vehicle is stopped such as at a stop light, the i-stop control stops/starts the engine automatically to improve fuel economy and reduce exhaust gas and idling noise.
•  The PCM determines whether to permit/inhibit i-stop control based on the signal from each input part and CAN communication.
•  The i-stop control includes the engine stop control, engine restart control, electric AT oil pump driver control, and vehicle roll prevention functions.

Control table

Control name

Control outline
Engine stop control
•  The engine is stopped when the i-stop (engine stop control) conditions are met.
Engine restart control
•  The engine restarts when the i-stop (engine restart control) conditions are met.
Electric AT oil pump driver control
•  Drives the electric AT oil pump to assure line pressure during an engine stop by the i-stop control.
Vehicle roll prevention function
•  Controls the traction control solenoid valve in the DSC HU/CM to maintain or decrease brake fluid pressure.


Block Diagram

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Operation


Engine stop control

i-stop (engine-stop control) permit condition
•  The conditions to stop the engine by the i-stop control are as follows:

Determination module

Determination item

Determination condition

Applicable PID
PCM
Vehicle speed
0 km/h {0 mph}
WSPD_SEN_LF
WSPD_SEN_RF
WSPD_SEN_LR
WSPD_SEN_RR
Brake pedal
Brake pedal is depressed while in D or M position.
However, no brake pedal conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) operation*1
TR
BPA
Brake fluid pressure
Brake fluid pressure is 1.35 MPa {13.8 kgf/cm2, 196 psi} or more while in D or M position. (Perform correction according to vehicle inclination angle)
However, no brake fluid conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) operation*1
TR
BRK_F_P_C
Accelerator pedal
Released
APP
Vehicle conditions
Vehicle is stopped in D position*2
TR
Steering speed
15 deg/s or less
STR_ROT_SPD
Steering angle
Within 65 ° of center to left and right
(After EPS control module learns center value)
STR_AB_EST
Steering torque
1.1 N·m {11 kgf·cm, 9.7 in·lbf} or less
STR_TRQ_S_M
i-stop OFF switch
OFF
I-Stop_OFF
Vehicle speed history
(After engine started and driven once)
3 km/h {2 mph} or more
I-Stop_VSP
DC-DC converter (i-ELOOP) output current (with i-ELOOP)
25 A or less
DCDC_OUT_A
i-ELOOP bypass mode operation condition (with i-ELOOP)
Bypass mode is not operated (BYPS_STAT: Bypass Off)
BYPS_STAT
Capacitor (i-ELOOP) voltage (with i-ELOOP)
14 V or more
DCDC_IN_V
Battery charge condition
65.72 % or more
BATT_SOC
Battery fluid temperature
0—70 °C {32—158 °F}
BATT_TEMP
Battery voltage
11.2 V or more
BATT_V
Power brake unit vacuum
−49.8 kPa {−0.508 kgf/cm2, −7.22 psi} or less
(value calculated by subtracting BARO from BBP)
BBP
BARO
Door (driver's side)
Closed
DOOR_D
Bonnet
Closed*3
HOOD
Vehicle inclination angle
Within ±7 ° when level (LON_ACCL_C: within ±0.121 G)
LON_ACCL_C
Seat belt (driver's side)
Fastened*4
SEAT_B_D
Battery condition setting
Completed
Not applicable
Steering angle sensor initial setting
Completed
Not applicable
Engine coolant temperature
55—110 °C {131—230 °F}
ECT
Intake air temperature
100 °C {212 °F} or less
IAT
Altitude
1,800 m or less (BARO: 81.5 kPa {0.831 kgf/cm2, 11.8 psi} or more)
Not applicable
System condition
i-stop related part DTCs are not recorded
Not applicable
Start stop unit
B+ (ROOM fuse) input
Yes
VPWR_B1
IG1 input
Yes
VPWR_IG1
ACC input
Yes
VPWR_ACC
IG1 output
Yes
RELAY_IG1
ACC output
Yes
RELAY_ACC
Push button
Not pressed
SSB_1
SSB_2
Door (all)
Closed
DOOR_ALL
Liftgate
Closed
TRUNK
Seat belt (driver's side)
Fastened*4
SEAT_B_D
Engine start
Engine was started by operating push button with key inside cabin (engine started first time)
Not applicable
Engine rotation speed
300 rpm or more is maintained after engine started
Not applicable
System condition
i-stop related part DTCs are not recorded
Not applicable
TCM
TCM detection condition
All met (I-Stop_EST: On)
I-Stop_EST
Panic stop
Brake pedal was not depressed suddenly within 4 s
Not applicable
TFT
20―117 °C {68—242 °F}
TFT
Gear position
Not in 2nd gear fixed mode
Not applicable
System condition
i-stop related part DTCs are not recorded
Not applicable
Climate control unit
Cabin temperature
Difference between target cabin temperature and actual cabin temperature is a certain value or less
(Cabin temperature control by A/C is normally performed)
Not applicable
A/C temperature
Setting other than MIN*5
Not applicable
Ambient temperature
−10―50 °C {14—122 °F}
Not applicable
Cold condition
Ambient temperature is 4 °C {39 °F} or more or evaporator temperature is 12 °C {54 °F} or less
Not applicable
MODE switch
Except DEFROSTER
Not applicable
Airflow volume control switch
Except MAX setting*6
Not applicable
System condition
i-stop related part DTCs are not recorded
Not applicable
DSC HU/CM
Operation request from PCM
Hill Launch Assist (HLA) control request signal from PCM is received
Not applicable
Wheel speed (4 wheels)
0 km/h {0 mph}
WSPD_SEN_LF
WSPD_SEN_RF
WSPD_SEN_LR
WSPD_SEN_RR
Brake pedal
Brake pedal is depressed
BRAKE_SW
Brake fluid pressure
Approx. 0.5 MPa {5 kgf/cm2, 73 psi} or more
BRK_F_P_C
Accelerator pedal
Released
APP
System condition
i-stop related part DTCs are not recorded
Not applicable

*1  :During Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) operation, the engine is stopped by i-stop control without having to depress the brake pedal.
*2  :After the vehicle is stopped, the engine stops if the selector lever is shifted to N position. In addition, if the selector lever is shifted to P position after the vehicle is stopped in D position, the engine stop condition by the i-stop control is maintained.
*3  :If the engine is started with the bonnet open, i-stop is inhibited until the engine is stopped.
*4  :If the seat belt is unfastened while the vehicle is stopped, i-stop is inhibited until a vehicle speed record is input once.
*5  :When the A/C set temperature is set to MAX, the PCM may inhibit the i-stop control.
*6  :When all of the other i-stop permit conditions related to the climate control unit are met even if the airflow volume control switch is on, the i-stop control is permitted.
i-stop (engine stop control)
•  When the i-stop (engine stop control) permit conditions are met, the PCM stops the engine based on the following controls:
―  Fuel injection control (fuel cut)
•  Engine speed is reduced by the fuel cut.
―  Drive-by-wire control (throttle valve open/closed)
•  By adjusting the throttle valve opening angle, the engine speed is reduced and the pumping loss is used to stop the engine.
―  Electric variable valve timing control (intake valve timing retard)
•  Intake valve timing retard is performed for engine restart by i-stop control.
―  Generator output control (generator load)
•  Engine speed is reduced by lowering the generator load.
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Engine restart control

i-stop (engine restart control) conditions
•  Conditions for restarting the engine during i-stop control (engine stopped) are as follows:

Detection module

Detection item

Determination conditions

PID
PCM
Vehicle speed
1 km/h {0.6 mph} or more
WSPD_SEN_LF
WSPD_SEN_RF
WSPD_SEN_LR
WSPD_SEN_RR
Brake pedal
•  Brake pedal is released → depressed while in P or N position
•  Brake pedal is released while in D or M position and AUTOHOLD is not operating.
However, no brake pedal conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) operation*1
TR
BPA
Brake fluid pressure
Brake fluid pressure is 0.35 MPa {3.6 kgf/cm2, 51 psi} or less while in D or M position and AUTOHOLD is not operating.
However, no brake fluid conditions during Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) operation*1
TR
BRK_F_P_C
Accelerator pedal
Accelerator pedal is depressed while in D or M position
TR
APP
Steering torque
4.0 N·m {41 kgf·cm, 35 in·lbf} or more while in D or M position
STR_TRQ_S_M
Steering angle
70 ° or more from center while in D or M position
(After EPS control module learns center value)
Not applicable
Shift operation
Operated from P or N position to D, M, or R position
TR
i-stop OFF switch
ON
I-Stop_OFF
DC-DC converter (i-ELOOP) output current (with i-ELOOP)
30 A or more
DCDC_OUT_A
Battery charge condition
65 % or less
BATT_SOC
Power brake unit vacuum
−47.8 kPa {−0.487 kgf/cm2, −6.93 psi} or more
(value calculated by subtracting BARO from BBP)
BBP
BARO
Driver not seated
•  Any one of the following conditions is met:
―  Seat belt (driver's side): Not fastened
―  Door (driver's side): Open
―  Bonnet: Open
SEAT_B_D
DOOR_D
TR
HOOD
Engine stop period by i-stop
120 s or more
Not applicable
Engine coolant temperature
55 °C {131 °F} or less
ECT
System condition
An i-stop related part DTC is recorded
Not applicable
Start stop unit
B+ (ROOM fuse) input
No
VPWR_B1
Remote transmitter authorization
When engine restart by remote transmitter authorization is requested
•  Any door is open without remote transmitter left in vehicle
•  Remote transmitter is outside of vehicle after any door is opened
Not applicable
System condition
An i-stop related part DTC is recorded
Not applicable
TCM
Gear position
Not in 2nd gear fixed mode
Not applicable
TFT
20 °C {68 °F} or less, or 117 °C {243 °F} or more
TFT
Vehicle speed
3 km/h {2 mph} or more
WSPD_SEN_LF
WSPD_SEN_RF
WSPD_SEN_LR
WSPD_SEN_RR
System condition
An i-stop related part DTC is recorded
Not applicable
Climate control unit
Cabin temperature (with full-auto air conditioner system)
Difference between target cabin temperature and actual cabin temperature is a certain value or more
(Cabin temperature control by A/C is normally performed)
STOP_ST
A/C set temperature (with full-auto air conditioner system)
•  If any one of the following conditions is met:
―  A/C switch: Turned ON and MAX COLD setting
―  MAX HOT setting
Not applicable
Ambient temperature
-10 °C {14 °F} or less, or 50 °C {122 °F} or more
Not applicable
MODE switch
DEFROSTER
Not applicable
Airflow volume control dial (with full-auto air conditioner system)
MAX setting
DEF_SW
System condition
An i-stop related part DTC is recorded
Not applicable
DSC HU/CM
System condition
An i-stop related part DTC is recorded
Not applicable

*1  :During Mazda Radar Cruise Control with Stop & Go function (MRCC with Stop & Go function) operation, the engine is not restarted by i-stop control even if the brake pedal is released.
i-stop (engine restart control)
•  When the i-stop (engine restart control) conditions are met, the PCM restarts the engine by the following controls:
―  Fuel injection control (from first time, fuel injection to specific cylinders (expansion stroke)
•  Fuel is injected to cylinders which are determined to be stopped at the expansion stroke. During i-stop control (engine stop), cylinders are identified based on the signal from the CKP sensor and fuel injection is enabled to those cylinders which are identified first as being stopped in the expansion stroke.
―  DC-DC converter control
•  When the engine is restarted by the i-stop control, the battery voltage is decreased to operate the starter by supplying power from the battery. When the starter operates, the supply voltage for electronic devices is increased by the DC-DC converter.
―  i-ELOOP control (i-stop mode) (with i-ELOOP)
•  During engine restarting by i-stop, the power supply source is divided between the battery and capacitor (i-ELOOP) to assure a supply of power to the vehicle’s electrical devices.
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Indicator illumination request

•  The PCM sends an i-stop indicator light (green)/i-stop warning light (amber) illumination or flash request to the instrument cluster according to the vehicle conditions.
•  The i-stop indicator light (green)/i-stop warning light (amber) illumination/flash request conditions are as follows:

IS: Engine stop by i-stop control
IR: Engine restart by i-stop control
×: Applicable
—: Not applicable

Vehicle condition

Vehicle condition

i-stop indicator light (green)/i-stop warning light (amber) display

Indicator (other)

Buzzer

Illumination on

Flash (0.5 s)

Illumination off

Illumination on/ Flash
Driving
IS conditions not met
—
—
—
×
—
—
IS conditions met*7
—
—
—
×
—
—
Vehicle parked
IS conditions not met*7
Idle
—
—
×
—
—
IS conditions met*7
IS
—
—
×
—
—
During IS
IS conditions met*7
IS
Green
—
—
—
—
IS continues normally
When the following conditions are met:
•  Brake depressed
•  D or M position (except 2nd gear fixed mode)
•  Steering angle less than 70°C {158°F} and steering torque less than 4.0 N·m {41 kgf·cm, 35 in·lbf}
When the following conditions are met:
•  Brake released
•  D or M position (except 2nd gear fixed mode) →N position
•  D or M position (except 2nd gear fixed mode) →N position →P position
IS continues
Green
—
—
—
—
During IS
IR request (driver's operation)
Engine start by key operation
IR
—
—
×*2
—
—
•  Brake pedal released → depressed while in P or N position
•  Brake pedal released while in D position or M position
•  Accelerator pedal depressed while in D or M position
•  Brake fluid pressure is 0.35 MPa {3.6 kgf/cm2, 51 psi} or less in D position or M position
•  Steering torque is 4.0 N·m {41 kgf·cm, 35 in·lbf} or more in D position or M position
•  Steering angle (D or M position (except 2nd gear fixed mode)): -70° or less or 70° or more
•  Shift operation
―  When changed to the M position (except 2nd gear fixed mode)
―  P or N position →D or M or R position
Any one of the following conditions is met:
•  Seat belt (driver's side): Not fastened
•  Door (driver's side): Open
•  Bonnet: Open
IR
—
—
×*2
—
—
During IS
Switches to unsafe condition (driver’s operation)
Door (driver) open
IS continues
Green
—
—
—
0.25 s intervals
IR request (vehicle request)
Any of the following conditions are met:
•  A/C request
•  Battery charge 65 % or less
•  Defroster switch on
•  Engine stop time by the i-stop control: 120 s or more
IR
—
—
×*2
—
—
Any of the following conditions are met:
•  Vehicle speed: 1 km/h {0.6 mph} or more
•  Power brake unit vacuum reduced
IR
—
—
—
—
•  Remote transmitter out of vehicle
IR*6
—
—
KEY warning light (red) flashing
Start stop unit normal buzzer
IR not functional
•  Cranking for 3 s or more when engine is restarted
Engine stall
Amber
—
—
Same illumination as normal engine stall condition
—
IS permit/inhibit implement
•  i-stop OFF switch on (long pressed for 0.5 s or more)
IS not authorized*8
Amber*3
—
—
—
Beep sound
1 time
•  i-stop OFF switch off (long pressed for 0.5 s or more)
IS authorized
—
—
×*4
—
Beep sound
1 time
System malfunction
IS not authorized
—
Amber*5
—
×*9
—

*1  :Changes illumination to IS when the conditions are met for driver operation (brake pedal force).
*2  :No flashing, turns off when the engine restarts.
*3  :Illuminates according to the i-stop OFF switch operation (long-press for 0.5 s or longer).
*4  :Turns off according to the i-stop OFF switch operation (long-press for 0.5 s or longer).
*5  :It may illuminate in amber when communication between PCM is cut.
*6  :Only when the advanced key is outside of the vehicle with the doors other than driver's door open.
*7  :The i-stop (engine-stop control) permit conditions differ depending on the driving condition. (See i-stop INDICATOR LIGHT (GREEN) [SKYACTIV-G 2.5T].)
*8  :If during engine stop by i-stop control, engine restarted by i-stop control.
*9  :If there is a battery related malfunction, the master warning light illuminates.
*10  :If the clutch pedal depressed and then it is released while the engine is cranking to restart by the i-stop control, engine stop by the i-stop control continues. If the same operation is repeated several times, the engine will stall.
*11  :Flashing before the engine restarts, turns off when the engine restarts.