FUEL INJECTION AMOUNT CONTROL [SKYACTIV-D 2.2]

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Outline

• The fuel injection amount is controlled by the opening of the nozzle in the fuel injector based on the signal from the PCM.

• The PCM learns and corrects the variation in the fuel injection amount of each cylinder.

Block diagram

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Operation

• The PCM calculates the fuel injection amount according to engine operation conditions.

• The fuel injection amount is determined according to the engine conditions.

Normal operation

• The value determined by the accelerator opening angle and engine speed is corrected according to the engine conditions^*1.

Engine protection/fail-safe

• Any of the following operations is determined according to the engine conditions.

― Decrease correction of fuel injection amount during normal operation (such as during high engine coolant temperature)

― Fix fuel injection amount (small amount) possible for limp-home driving (such as when accelerator pedal position sensor is malfunctioning)

*1 :Each temperature/pressure, gear, power generation condition, A/C condition

Fuel cut

• If any of the following conditions is met, the PCM performs fuel cut under the following conditions:

Fuel cut table

Control name	Control outline
Excessive speed fuel cut	Purpose • Engine protection Control condition • When engine speed is 5600 rpm or more
Deceleration fuel cut	Purpose • Improved fuel economy Control conditions • When engine conditions are as follows: ― Accelerator pedal is fully closed ― Engine speed is specified value or more ― Vehicle speed is specified value or more
Sensor malfunction fuel cut	Purpose • To prevent engine damage from abnormal combustion caused by the inability to determine the piston position correctly due to an engine speed signal input error. Control condition • When a malfunction in the crankshaft position sensor is detected
Theft prevention	Purpose • To prevent theft Control condition • Immobilizer system related information (engine start prohibited) received from start stop unit
Part protection (MTX)	Purpose • Protection of dual-mass flywheel Control condition • Engine speed of 500 rpm or less continues for 2 s while vehicle is in gear
Fuel-cut at time of collision	Purpose • For safety assurance Control conditions • Collision signal from SAS control module is received

Fuel injection amount learning

• The PCM verifies the variation in fuel injection amount by calculating fluctuations in engine speed.

• The fuel injection amount of each cylinder is increased/decreased by correcting the fuel injection amount to each cylinder according to the changes in engine speed so that the fluctuation in engine speed is reduced.

• The correction amount is recorded in the PCM as a learned value, and remains recorded until it is updated.

Auto-learning

• The PCM periodically implements auto learning of the fuel injection.The idling sound may fluctuate due to the fuel injectors performing high/low fuel injection pressure during learning.

• If all of the following conditions are met, the PCM implements the fuel injection amount learning.

― Shift lever position: Neutral (MTX)

― Selector lever position: Either D position, N position, or P position (ATX)

― Vehicle speed: 0 km/h {0 mph}

― Engine coolant temperature: 70—95 °C {158—203 °F}

― A/C non-operation

― Accelerator opening angle: 0%

― DPF regeneration control not implemented

• If any of the implementation conditions is not met during the fuel injection amount learning, the fuel injection amount learning is canceled, but it will resume when the implementation conditions are met again.

Manual learning

― The fuel injection amount learning can be implemented using the Mazda Modular Diagnostic System (M-MDS) or a check connector.

― It is necessary to perform the fuel injection amount learning periodically (once/year) to maintain performance.

Cruise Control

• 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/CANCEL switch: On (long-press)

― Cruise control related DTCs (P0571:00) 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.

― OFF/CANCEL switch: On

― Transaxle range sensor: P/N position (ATX)

― Clutch switch: ON (clutch pedal depressed for 5 s or more) (MTX)

― Neutral switch: ON (neutral condition for 2 s or more) (MTX)

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

― Brake switch: ON (brake pedal depressed)

― Brake fluid pressure: 0.3 MPa {3 kgf/cm², 44 psi} or more

― Actual vehicle speed is 15 km/h {9.3 mph} or more lower than the set vehicle speed during cruise control (during ascent)

― Parking brake lever pulled

Cruise control function

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

Function List

Function	Contents
Accelerating	• When the RESUME/+ switch is continuously pressed while driving in cruise control, the PCM gradually increases the set vehicle speed.
Coasting	• When the SET/- switch is continuously pressed while driving in cruise control, the PCM gradually decreases the set vehicle speed.
Resume	• When the RESUME/+ switch signal is send 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/m (speedometer displayed in [km/m])/1 mph (speedometer displayed in [mph]). ― RESUME/+ switch off ― 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/m (speedometer displayed in [km/m])/1 mph (speedometer displayed in [mph]) and the throttle valve actuator is controlled so that the vehicle speed is close to the set vehicle speed. ― During cruise control ― The RESUME/+ switch switches from off to on ― When actual vehicle speed is lower (set vehicle speed +2 km/h {+1 mph})
Downshift	• When the following conditions are met, a downshift signal is sent to the TCM (ATX) via CAN. ― RESUME/+ switch on ― Target vehicle acceleration is not reached • If the increase in vehicle speed on the down slope is high, the PCM sends a down shift signal to the TCM (ATX).

Brake override system

Brake override system operation conditions

• It gives priority to the brake operation if a malfunction occurs with the accelerator pedal such as if the accelerator pedal is depressed and does not return.The fuel injection amount is reduced if the brake pedal is depressed while the accelerator pedal is in a depressed condition until the vehicle is safely decelerated and comes to a complete stop.

Operation start conditions

•  If either one of the following conditions is met with the brake pedal depressed for the specified time^*1 or more while the accelerator pedal is depressed, the PCM adjusts the fuel injection amount so that the engine speed is 1,000 rpm.

While driving vehicle

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

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

―  Engine speed: 875 rpm or more

While vehicle is stopped

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

―  Shift lever position: neutral (MTX)

―  Selector lever position: N position (ATX)

―  Engine speed: 875 rpm or more

Operation complete conditions

•  If the following conditions are met while the brake override system is operating, the PCM stops the operation of the brake override system and controls the fuel injection amount according to the throttle valve opening angle.

―  Accelerator pedal not depressed

―  Brake pedal not depressed

Note

•  The brake override system operation stops by switching the ignition off.

*1 :Specified time is 0.6 to 10 s according to braking force calculated in PCM.

Prevention of unnecessary brake override system operation

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

Cancel conditions

•  If the releasing procedure is implemented with the following conditions met within 30 s after switching the ignition ON (KOEO), the brake override system does not operate until the recovery condition is met.

―  Shift lever position: neutral (MTX)

―  Selector lever position: N position (ATX)

―  Vehicle speed: 0 km/h {0 mph}

Releasing procedure

1.  Depress the brake pedal for 10 s with the accelerator pedal released.

2.  Repeatedly depress and release the accelerator pedal fully three times with the brake pedal depressed.

3.  Release the brake pedal

Recovery condition

•  The cancel conditions are reset when the ignition is switched off while the brake override system is canceled. As a result, the brake override system can operate.

Master warning light illumination request

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

― Brake switch (No.1 signal) has a malfunction

― Brake switch (No.2 signal) has a malfunction

Master warning light flash request

• If the cancel condition for preventing unnecessary operation of the brake override system is implemented, the PCM sends a master warning light flash request signal to the instrument cluster.The driver is notified that the brake override system has been cancelled by the flashing of the master warning light.

Fail-safe

• To prevent engine damage, the engine speed is restricted to 3,000 rpm or less when the engine coolant temperature is -10 °C {14 °F} while the ignition is switched ON. (Maximum 190 s period)