Mitsubishi Pajero Pinin. Manual - part 161

ENGINE AND EMISSION CONTROL – 

Emission Control System

EGR valve

Throttle
body

EGR valve

17-13

EXHAUST GAS RECIRCULATION (EGR) SYSTEM

GENERAL INFORMATION

The exhaust gas recirculation (EGR) system lowers
the nitrogen oxide (NOx) emission level. When the
air/fuel mixture combustion temperature is high, a
large quantity of nitrogen oxides (NOx) is generated
in the combustion chamber. Therefore, this system
recirculates part of emission gas from the exhaust

port of the cylinder head to the combustion chamber
through the intake manifold to decrease the air/fuel
mixture combustion temperature, resulting in
reduction of NOx.
The EGR flow rate is controlled by the EGR valve
so as not to decrease the driveability.

OPERATION

The EGR valve is being closed and dose not
recirculate exhaust gases under one of the following
conditions. Otherwise, the EGR valve is opened
and recirculate exhaust gases.

D

The engine coolant temperature is low.

D

The engine is at idle.

D

The throttle valve is widely opened.

SYSTEM DIAGRAM

Air flow sensor

Engine coolant tem-
perature sensor

Crank angle sensor

Control
relay

Engine-ECU

Battery

Throttle body

EGR valve
(Stepper
motor)

Throttle position sensor

COMPONENT LOCATION

ENGINE AND EMISSION CONTROL – 

Emission Control System

17-14

EXHAUST GAS RECIRCULATION (EGR)
CONTROL SYSTEM CHECK

Refer to GROUP 13A – Troubleshooting.

EGR VALVE (STEPPER MOTOR) CHECK

Checking the Operation Sound

1.

Check that the operation sound of the stepper motor can
be heard from the EGR valve when the ignition switch
is turned to ON (without starting the engine).

2.

If the operation sound cannot be heard, check the stepper
motor drive circuit.

NOTE
If the circuit is normal, the cause is probably a malfunction
of the stepper motor or of the engine-ECU.

Checking the Coil Resistance

1.

Disconnect the EGR valve connector.

2.

Measure the resistance between the EGR valve-side
connector terminal No.2 and terminal No.1 or terminal
No.3.

Standard value: 10 – 20 

Ω

 (at 20

_

C)

3.

Measure the resistance between the EGR valve-side
connector terminal No.5 and terminal No.4 or terminal
No.6.

Standard value: 10 – 20 

Ω

 (at 20

_

C)

Throttle
body

EGR valve

ENGINE AND EMISSION CONTROL – 

Emission Control System

17-15

Operation Check

1.

Remove the EGR valve.

2.

Connect the special tool (test harness set) to the EGR
valve-side connector.

3.

Connect terminal No.2 and terminal No.5 to the positive
(+) terminal of power supply of approximately 6 V.

4.

Connect each clip to the negative (–) terminal of power
supply in the order given below to test if any vibration
occurs (as though the stepper motor is shaking slightly)
due to the operation of the stepper motor.

(1) Connect terminal No.1 and terminal No.4 to the

negative (–) terminal of the power supply.

(2) Connect terminal No.3 and terminal No.4 to the

negative (–) terminal of the power supply.

(3) Connect terminal No.3 and terminal No.6 to the

negative (–) terminal of the power supply.

(4) Connect terminal No.1 and terminal No.6 to the

negative (–) terminal of the power supply.

(5) Connect terminal No.1 and terminal No.4 to the

negative (–) terminal of the power supply.

(6) Repeat the test in the order from (5) to (1).

5.

If the results of testing show that the vibration could be
felt, the stepper motor is normal.

Cleaning the EGR Valve

Remove the EGR valve, and then check if the EGR valve
is stuck and carbon is accumulated in it. If so, use a wire
brush to clean the EGR valve.

Caution
Do not use a cleaning solvent. Solvent will penetrate to
the motor and malfunction of EGR valve will result.

EGR valve

Battery

MB991658

ENGINE AND EMISSION CONTROL – 

Emission Control System

17-16

EGR VALVE

REMOVAL AND INSTALLATION

Pre-removal and Post-installation Operation

D

Engine Coolant Draining and Supplying (Refer to
GROUP 14 – On-vehicle Service.)

D

Engine Cover Removal and Installation

1

9

24 Nm

24 Nm

19 Nm

10

19 Nm

8

7

5

2

3

10 – 12 Nm

4

7

6

Removal steps

A

A

"

1. Fuel pump protector
2. EGR valve harness connector 

connection

3. Water hose
4. Water pipe
5. Water hose

6. EGR valve and support assembly
7. EGR pipe gasket
8. EGR valve
9. EGR valve gasket

10. Water hose

REMOVAL SERVICE POINT

A

A

"

FUEL PUMP PROTECTOR REMOVAL

Lift up the transmission with a jack to create clearance between
the engine and front deck, and then remove the fuel pump
protector.