Mazda X-5. Manual — part 37
CONTROL SYSTEM
01–40–21
01–40
Determination of Effective Injection Time
• The PCM divides the engine operation conditions into control zones according to engine speed and engine
load and determines the effective injection time at each control zone to perform optimum air/fuel ratio control in
all engine driving ranges.
Start zone
Purpose
• Improved engine startability
Operation condition
• When engine speed is 500 rpm or less.
Determination of fuel injection time
• According to engine coolant temperature (ECT sensor) and engine speed (CKP sensor)
Feedback Zone
Purpose
• Improved fuel economy
• Improved exhaust gas purification
Control condition
• During engine operation other than high load volume increase zone and engine start zone.
Determination of fuel injection time
• During normal driving, the amounts of various correction types are added to the basic injection time to set to
the theoretical air/fuel ratio.
High load volume increase zone
Purpose
• Improved driveability
• TWC protection
Control condition
• Either the charging efficiency or the throttle valve opening angle is a fixed value or more.
Determination of fuel injection time
• Corrections are added to the basic injection amount and the high load coefficient is calculated according to the
engine speed, mass intake airflow amount and the throttle valve opening angle.
Excessive speed fuel cut zone
Purpose
• Engine protection
Control conditions
• When the engine speed is 7,000 rpm or more (WOT).
• When engine speed is 5,500 rpm or more and the engine coolant temperature is approx. -15 °C {5 °F} or less.
• When the following conditions continue for 2 min or more:
— Vehicle is stopped.
— Engine speed is 2,500 rpm or more.
— Engine coolant temperature is approx. 112
°C {234 °F}.
Note
• The PCM determines that the driver continues to unintentionally depress the accelerator pedal
Determination of fuel injection time
• Fuel injection time is set to 0 (fuel cut).
START
ZONE
FEEDBACK ZONE
HIGH LOAD VOLUME
INCREASE ZONE
EXCESSIVE SPEED
FUEL CUT ZONE
DECELERATION
FUEL CUT ZONE
INTAKE AIR AMOUNT
LARGE
ENGINE SPEED
HIGH
C3U0140S015
CONTROL SYSTEM
01–40–22
Deceleration fuel cut zone
Purpose
• Improved fuel economy
• Prevents overheating of the catalytic converter
Control conditions
• When the engine conditions are as follows (10 s or longer after engine start):
— Fully closed throttle valve
— When the engine speed is at set value or more (differs depending on the ECT) (charging efficiency at fixed
value or more, mass airflow sensor normal)
Determination of fuel injection time
• The fuel injection time is set to 0 (fuel cut).
Calculation method list for fuel injection time
A: Fuel injection time base, B: Correction for fuel injection time
Contents
(Fuel injection time, calculation method, or determination method)
Control zone
Injection time at start
Set value according to engine coolant temperature (low engine
coolant temperature
→long injection time)
A
Basic injection time
Basic injection time = charging efficiency x fuel flow coefficient
A
A
Fuel cut
Fuel injection time = 0
A
A
Ineffective injection
time
Set time according to injector performance
A
A
A
Volume increase
correction at engine start
Purpose: Maintains stability of engine speed just after engine start
Correction condition
• Specified time according to engine coolant temperature directly
after engine start
Correction amount
• Low engine coolant temperature→large correction
• Low intake air temperature→large correction
B
B
Front HO2S feedback
correction
Purpose: Controls air/fuel ratio to the theoretical air/fuel ratio
Correction condition
• When engine coolant temperature is at set value or more
Correction amount
• Front HO2S electromotive force is approx. 0.45 V or
more
→volume decrease correction
• Front HO2S electromotive force is approx. 0.45 V or
more
→volume increase correction
B
Rear HO2S feedback
correction
Purpose: Corrects feedback amount according to deterioration of
front HO2S and catalytic converter
Correction condition
• Engine coolant temperature is at set value or more
• Engine speed is 500—4,250 rpm
• Charging efficiency is 10—80%
Correction amount
• According to rear HO2S electromotive force→correction
B
D-range correction
(AT)
Purpose: Ensures engine speed stability during D-range shifting
Correction condition
• Throttle valve fully-closed and shifted into D range
Correction amount
• Low engine coolant temperature→large correction
B
Star
t
Feedbac
k
High load v
olume
increase
Excessive speed
fuel cut
Deceleration fuel
cut
CONTROL SYSTEM
01–40–23
01–40
Fuel Cut
• Includes fuel cut under the following conditions except fuel cut at excessive engine speed according to engine
operation and deceleration fuel cut.
Sensor damage fuel cut
Purpose
• To prevent engine damage from abnormal ignition due to a malfunction input of a cylinder identification or the
engine speed signal.
Control condition
• When damage to the crankshaft position sensor or camshaft position sensor is detected.
Dechoke control
Purpose
• To improve engine starting startability when spark plugs are flooded.
Control conditions
• When cranking close to fully-open throttle valve
High load volume
increase correction
Purpose: Improved engine output, decrease of exhaust gas
temperature
Correction condition
• According to engine speed when the throttle valve opening
angle is the fixed value or more, otherwise, according to engine
speed and charging efficiency
Correction amount
• High engine speed, high charging efficiency→large correction
B
Warm-up volume
increase correction
Purpose: When engine coolant temperature is low, maintains
combustion stability
Correction condition
• While at set engine coolant temperature
Correction amount
• High charging efficiency, low engine coolant temperature→large
correction
B
B
A/C load increase
correction
Purpose: Maintains engine speed stability during A/C operation
Correction condition
• A/C is operating
Correction amount
• Low engine coolant temperature→large correction
B
B
Acceleration increase
correction
Purpose: Corrects fuel injection delay during acceleration to ensure
drive stability
Correction condition
• When acceleration amount (change in the amount of charging
efficiency) is at set value or more
Correction amount
• Low engine coolant temperature→large correction
• Large acceleration amount→large correction
B
B
Deceleration volume
increase correction
Purpose: Ensures engine speed stability after fuel cut recovery
Correction condition
• When recovery from fuel cut
Correction amount
• Low engine speed→large correction
B
Learning correction
Purpose: Corrects deviation in air/fuel ratio from changes due to
aged deterioration of mechanical devices
Correction condition
• Under any condition except purge control
Correction amount
• Learning value based on average of feedback correction value
B
B
Intake air pressure
correction
Purpose: Corrects ineffective charging time deviation from change
in intake manifold vacuum
Correction condition
• Under any condition except start zone
Correction amount
• More intake manifold vacuum→large correction
B
B
CONTROL SYSTEM
01–40–24
Fuel cut during immobilizer system activation
Purpose
• To prevent vehicle theft
Execution conditions
• When an engine stop request signal is received from the immobilizer system, the PCM force-stops the fuel
injectors. Therefore the engine stops.
End Of Sie
FUEL PUMP CONTROL OUTLINE [LF]
E5U014000000N28
• The fuel pump is operated when the ignition switch is turned to the ON position to improve startability. As a
result, fuel pressure increases rapidly and stable fuel control is performed.
End Of Sie
FUEL PUMP CONTROL BLOCK DIAGRAM [LF]
E5U014000000N29
End Of Sie
FUEL PUMP CONTROL OPERATION [LF]
E5U014000000N30
Operation Condition
• When the ignition switch is turned to the ON position, the PCM turns the fuel pump relay on for 1 s, then off.
• When it is detected that the CKP sensor signal rises during cranking, the fuel pump relay turns on.
• When the engine is stopped, the fuel pump relay turns off.
Operation Inhibition Condition
• When receiving an engine stop request signal from the immobilizer system, the PCM force-stops control of the
fuel injectors. As a result, the engine does not start.
End Of Sie
ELECTRONIC SPARK ADVANCE (ESA) CONTROL OUTLINE [LF]
E5U014000000N31
• Controls ignition to optimum timing according to engine operation conditions.
• Serviceability has been improved by eliminating the necessity of ignition timing.
• The PCM determines the engine operation conditions based on input signals from sensors, blocks current to
the ignition coils by the calculated ignition timing, and discharges (ignition) the sparks plugs based on the effect
of electromagnetic mutual induction.
End Of Sie
CKP SENSOR
IGNITION SWITCH
FUEL PUMP RELAY
PCM
E5U140ZW5401
PCM
PCM
M
M
ENGINE STOP REQUEST SIGNAL
NOT RECEIVED
ENGINE STOP REQUEST SIGNAL RECEIVED
FROM MAIN RELAY FROM BATTERY
FROM MAIN RELAY FROM BATTERY
FUEL PUMP RELAY
FUEL PUMP RELAY
FUEL PUMP
FUEL PUMP
C3U0140S017
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