Mazda X-5. Manual — part 39

CONTROL SYSTEM

01–40–29

01–40

EVAPORATIVE PURGE CONTROL BLOCK DIAGRAM [LF]

E5U014000000N38

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EVAPORATIVE PURGE CONTROL OPERATION [LF]

E5U014000000N39

Determination of Purge Solenoid Valve Energization Time

• The PCM determines the target purge flow amount according to engine operation conditions as the basic flow

amount. The actual operation delays the build-up of operation current from coil inductance and corrects
energization time according to fluctuation in battery voltage to cause operation delay based on the mass of the
needle valve and plunger, and spring resistance. The lower the rate of battery positive voltage, the longer the
energization time.

Calculation Method for Purge Flow Amount

• The PCM determines the purge flow amount through the addition of each correction to the basic purge flow

amount.

Operation Conditions

• For purge control during normal driving, the PCM sends a duty signal to the purge solenoid valve when all of

the following conditions are met.

— Fuel injection control is in the feedback zone or the high load volume increase zone.

— Airflow passage damage related DTC is not stored.

— Engine coolant temperature is 70

°C {158 °F} or more.

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MAF SENSOR

IAT SENSOR

MAP SENSOR

CKP SENSOR

BARO SENSOR

FRONT HO2S

BATTERY

NEUTRAL SWITCH (MT)

TR SWITCH (AT)

PURGE SOLENOID VALVE
ENERGIZATION TIME

PURGE FLOW AMOUNT

BASIC PURGE FLOW
AMOUNT

CORRECTIONS

PURGE SOLENOID
VALVE

PCM

TP SENSOR NO.1, NO.2

ECT SENSOR

BRAKE SWITCH

NO.1, NO.2

E5U140ZT5007

Contents

Calculation or determination method of purge flow amount and correction

Basic purge flow amount

The basic purge flow amount is determined by multiplying the intake air temperature
correction to the purge mass volume which is calculated by multiplying the base purge rate
and the intake air mass volume, which differs according to engine conditions.

Correction

Purge startup

correction

Purpose: Prevents a sudden change in air/fuel ratio during the startup of purge control.

During purge control startup

• When purge control operation conditions are met→correction

Volume decrease

correction

Purpose: Decreases the amount of purge flow and stabilize the air/fuel ratio.

When the fuel injection control feedback correction value is unstable

• According to the front HO2S feedback condition

CONTROL SYSTEM

01–40–30

EGR CONTROL OUTLINE [LF]

E5U014000000N34

• Adjusts the EGR valve to the optimum opening angle according to engine operation conditions.

• The valve in the EGR valve allows for more precise control by being driven by the stepping motor.

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EGR CONTROL BLOCK DIAGRAM [LF]

E5U014000000N35

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EGR CONTROL OPERATION [LF]

E5U014000000N36

Stepping Motor Operation Principles

• The PCM opens/closes the EGR valve by controlling the amount of stepping motor rotation (step number).

• The stepping motor operates by the combination of coils No.1—4, according to the stepping motor step

number.

Energization condition for each coil

ON: Energization, OFF: Non-energization

Example of energization condition for each coil and step number

ON: Energization, OFF Non-energization

• The energization condition of stepping motor coils No.1—4 can be verified by verifying the step number from

“SEGRP” on the PID/data monitor function of the WDS.

MAF SENSOR

IAT SENSOR

ECT SENSOR

PCM

CKP SENSOR

NEUTRAL SWITCH (MT)

CPP SWITCH (MT)

BATTERY

VEHICLE SPEED SIGNAL

EGR VALVE OPERATION
STEP NUMBER

TARGET EGR
VALVE
POSITION

CURRENT
EGR VALVE
POSITION

BASIC EGR VALVE
POSITION

CORRECTIONS

EGR VALVE

TR SWITCH (AT)

TP SENSOR NO.1, NO.2

MAP SENSOR

BARO SENSOR

E5U140ZT5006

When current step number divided
by eight

0

1

2

3

4

5

6

7

Coil No.1

ON

ON

ON

OFF

OFF

OFF

OFF

OFF

Coil No.2

OFF

OFF

OFF

OFF

ON

ON

ON

OFF

Coil No.3

OFF

OFF

ON

ON

ON

OFF

OFF

OFF

Coil No.4

ON

OFF

OFF

OFF

OFF

OFF

ON

ON

Step number

0

1

2

3

4

5

6

7

8

9

10

30

52

Coil No.1

ON

ON

ON

OFF

OFF

OFF

OFF

OFF

ON

ON

ON

OFF

OFF

Coil No.2

OFF

OFF

OFF

OFF

ON

ON

ON

OFF

OFF

OFF

OFF

ON

ON

Coil No.3

OFF

OFF

ON

ON

ON

OFF

OFF

OFF

OFF

OFF

ON

OFF

ON

Coil No.4

ON

OFF

OFF

OFF

OFF

OFF

ON

ON

ON

OFF

OFF

ON

OFF

CONTROL SYSTEM

01–40–31

01–40

Control Outline

• The PCM constantly calculates the optimum target EGR valve position according to the engine operation

conditions and controls the EGR stepping motor step number so that the current EGR valve position is close to
the target.

• If the current EGR valve position is smaller than the target EGR position (deviation is a positive number), the

PCM increases the stepping motor step number and opens the EGR valve. If larger (deviation is a negative
number), the PCM decreases the stepping motor step number and closes the EGR valve. Step numbers are
increased or decreased by one step at a time.

Target EGR Valve Position

• The PCM determines the value to increase or decrease the EGR valve opening angle according to the engine

operation conditions. The PCM determines the target EGR valve position through each correction based on the
basic EGR valve position that is set according to the engine speed and load.

Target EGR valve position determination table

*1

: The charging efficiency is the ratio of the actual amount of intake air to the maximum air charging amount

(mass volume) of the cylinder. This value increases proportionately to the increase in engine load.

*2

: The correction is to restrict the basic EGR valve position value. Except for the above conditions and inhibition

conditions, the correction value is 100%, and the target EGR valve position equals the EGR valve position
value.

Inhibition Conditions

• To improve driveability and ensure exhaust emission performance, the EGR valve closes when any of the

following conditions are met.

— When throttle valve is fully closed

— When vehicle is stopped

— When the fuel injection control is in the high volume increase zone

— The engine coolant temperature is 50

°C {122 °F} or less

— During deceleration

— Engine speed is less than 1,200 rpm or more than 4,200 rpm

— Charging efficiency is less than 12.5% or more than 75%

— During traction control

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Contents

Method for calculating or determining the EGR valve position and correction

Basic EGR valve position

Within steps 0—52 in the stepping motor determined as follows:

• When the engine speed is 1,200—4,200 rpm and the charging efficiency

*1

is within

12.5—75%, the engine speed and charging efficiency are determined to be at basic
position

• When the EGR control inhibition conditions are met, step 0

Correction

*2

Engine coolant

temperature

correction

Purpose: Improved driveability

Engine coolant temperature is 50—55

°C {122—131 °F}

• The step number is restricted between 0—50% of the basic EGR valve position (low

engine coolant temperature—low step number) according to the engine coolant
temperature.

Engine coolant temperature is 55—65

°C {131—149 °F}

• The step number is restricted between 50—100% of the basic EGR valve position (low

engine coolant temperature

→low step number) according to the engine coolant

temperature.

Intake air

temperature

correction

Purpose: Improved driveability

Intake air temperature is 50

°C {122 °F} or less

• Step number is restricted to 100% of the basic EGR valve position (basic EGR valve

position = step number)

Intake air temperature is 50

°C {122 °F} or more

• Step number is restricted between 40—100% of basic EGR valve position (low intake

air temperature

→large step number)

Acceleration/

deceleration

correction

Purpose: Improved driveability

During acceleration/deceleration, when the throttle valve opening angle

fluctuation rate is the set value or more

• During acceleration→step number is restricted to 20% of basic EGR valve position

• During deceleration→step number is restricted to 0% of basic EGR valve position

CONTROL SYSTEM

01–40–32

HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OUTLINE [LF]

E5U014000000N40

• Stabilized oxygen concentrations, even when the exhaust gas temperature is low, are detected by controlling of

the HO2S, enabling feedback control of the fuel injection control even during cold-engine starting, improving
emission performance when cold.

• When the exhaust gas temperature is high, the HO2S is protected from sharp rises in its temperature by

stopping energization to the HO2S heater.

• Emission performance improvement and protection of the HO2S have both been achieved by the duty control

of the front and rear HO2S according to the engine operation conditions (exhaust gas temperature).

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HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL BLOCK DIAGRAM [LF]

E5U014000000N41

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HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION [LF]

E5U014000000N42

Operation Conditions

• The PCM operates the HO2S when the following conditions are met.

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PCM

ECT SENSOR

IAT SENSOR

CKP SENSOR

TP SENSOR NO.1, NO.2

MAF SENSOR

MAP SENSOR

BARO SENSOR

REAR HO2S HEATER

FRONT HO2S HEATER

BATTERY

E5U140ZW5402

HO2S

Activation condition

Drive signal

Front

• After engine start

• After the engine has started and a fixed period

of time has elapsed (the elapsed time period
after the engine starts is determined by ECT).

• ECT is –10 °C {14 °F} or more.

• Battery positive voltage is 9 V or more and less

than 16 V.

• MAF sensor is normal (no DTC is stored in

PCM).

• The PCM outputs a duty signal.

• The element temperature is measured by the

impedance of the HO2S and a duty ratio is
determined.

Rear

• Starter is off

• After engine start

• After the engine has started and a fixed period

of time has elapsed (the time period after the
engine starts lengthen if the ECT falls below
0

°C {32°F}.

• ECT is –10 °C {14 °F} or more.

• Battery positive voltage is 9 V or more and less

than 16 V.

• Charging efficiency is the fixed value or less, or

during fuel cut.

• The PCM outputs a duty signal.