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)

Basic injection time

Basic injection time = charging efficiency x fuel flow coefficient

Fuel cut

Fuel injection time = 0

Ineffective injection
time

Set time according to injector performance

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

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

→volume decrease correction

• Front HO2S electromotive force is approx. 0.45 V or

→volume increase correction

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

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

Star

Feedbac

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

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

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

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

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

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

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

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.

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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

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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.

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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

ENGINE STOP REQUEST SIGNAL
NOT RECEIVED

ENGINE STOP REQUEST SIGNAL RECEIVED

FROM MAIN RELAY FROM BATTERY

FUEL PUMP RELAY

FUEL PUMP

C3U0140S017

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