Mitsubishi Pajero Pinin. Manual - part 155

ENGINE ELECTRICAL –  

Ignition System

16-14

IGNITION SYSTEM

GENERAL

OUTLINE OF CHANGES

The following service procedures have been established to correspond to the addition of vehicles with
4G9-MPI engine. Other service procedures are the same as for the 4G9-GDI engine.

GENERAL INFORMATION

This system is equipped with two ignition coils (A
and B) with built-in power transistors for the No.
1 and No. 4 cylinders and the No. 2 and No. 3
cylinders respectively.
Interruption of the primary current flowing in the
primary side of ignition coil A generates a high
voltage in the secondary side of ignition coil A.
The high voltage thus generated is applied to the
spark plugs of No. 1 and No. 4 cylinders to generate
sparks. At the time that the sparks are generated
at both spark plugs, if one cylinder is at the
compression stroke, the other cylinder is at the
exhaust stroke, so that ignition of the compressed
air/fuel mixture occurs only for the cylinder which
is at the compression stroke.
In the same way, when the primary current flowing
in ignition coil B is interrupted, the high voltage
thus generated is applied to the spark plugs of No.
2 and No. 3 cylinders.
The engine-ECU turns the two power transistors
inside the ignition coils alternately on and off. This

causes the primary currents in the ignition coils to
be alternately interrupted and allowed to flow to
fire the cylinders in the order 1– 3– 4– 2.
The engine-ECU determines which ignition coil
should be controlled by means of the signals from
the camshaft position sensor which is incorporated
in the camshaft and from the crank angle sensor
which is incorporated in the crankshaft. It also
detects the crankshaft position in order to provide
ignition at the most appropriate timing in response
to the engine operation conditions. It also detects
the crankshaft position in order to provide ignition
at the most appropriate timing in response to the
engine operation conditions.
When the engine is cold or operated at high altitudes,
the ignition timing is slightly advanced to provide
optimum performance.
When the automatic transmission shifts gears, the
ignition timing is also retarded in order to reduce
output torque, thereby alleviating shifting shocks.

SYSTEM DIAGRAM

Intake air temperature sensor

Engine coolant temperature
sensor

Camshaft position sensor

Crank angle sensor

Ignition switch-ST

Vehicle speed sensor

Engine-ECU

Ignition coil A

Ignition coil B

Ignition switch

Spark plug

Battery

Cylinder

Detonation sensor

Air flow sensor

Barometric pressure sensor

Inhibitor switch

Ignition
failure
sensor

To tachometer

No.3

2

4

1

ENGINE ELECTRICAL –  

Ignition System

16-15

IGNITION COIL SPECIFICATIONS

Items

Specifications

Type

Molded 2-coil

SPARK PLUG SPECIFICATIONS

Items

Specifications

NGK

BKR5E-11

DENSO

K16PR-U11

SERVICE SPECIFICATIONS

IGNITION COIL

Items

Standard value

Secondary coil resistance   k

Ω

8.5 –  11.5

SPARK PLUG

Items

Standard value

Spark plug gap mm

1.0 –  1.1

RESISTIVE CORD

Items

Limit

Resistance k

Ω

Max.22

IGNITION FAILURE SENSOR

Items

Standard value

Resistance 

Ω

0.1 or less

SPECIAL TOOL

Tool

Number

Name

Use

MD998773

Detonation sensor
wrench

Detonation sensor removal and installation

ENGINE ELECTRICAL –  

Ignition System

16-16

ON-VEHICLE SERVICE

IGNITION COIL (WITH BUILT-IN POWER
TRANSISTOR) CHECK

Check by the following procedure, and replace if there is a
malfunction.

SECONDARY COIL RESISTANCE CHECK

Measure the resistance between the high-voltage terminals
of the ignition coil.

Standard value: 8.5 –  11.5 k

Ω

PRIMARY COIL AND POWER TRANSISTOR
CONTINUITY CHECK

NOTE
1.

An analogue-type circuit tester should be used.

2.

Connect the negative (– ) prove of the circuit tester to
terminal 1.

Caution
This test must be performed quickly (in less than 10
seconds) to prevent coil from burning and power transistor
from breakage.

Voltage: 1.5V

Terminal No.

g

1

2

3

When current is
flowing

When current is
not flowing

RESISTIVE CORD CHECK

Measure the resistance of the all spark plug cables.
1.

Check cap and coating for cracks.

2.

Measure resistance.

Limit: Max. 22 k

Ω

1.5 V

–

+

ENGINE ELECTRICAL –  

Ignition System

16-17

SPARK PLUG CHECK AND CLEANING 

1.

Remove the ignition coils and spark plug cables.

Caution
When pulling off the spark plug cable from the plug
always hold the cable cap, not the cable.

2.

Remove the spark plugs.

3.

Check for burned out electrode or damaged insulator.
Check for even burning.

4.

Remove carbon deposits with wire brush or plug cleaner.
Remove sand from plug screw with compressed air.

5.

Use a plug gap gauge to check that the plug gap is within
the standard value range.

Standard value: 1.0 –  1.1 mm

If the plug gap is not within the standard value range,
adjust by bending the earth electrode.

6.

Clean the engine plug holes.

Caution
Be careful not to allow foreign matter in cylinders.

7.

Install the spark plugs.

8.

Install the ignition coils and spark plug cables.

IGNITION FAILURE SENSOR CHECK

NOTE
An analog-type circuit tester should be used.
Check that the resistance between terminals 3 and 4 is at
the standard value.

Standard value: 0.1 

Ω

 or less

CAMSHAFT POSITION SENSOR CHECK

Refer to GROUP 13C –  Troubleshooting. <4G9-MPI>

CRANK ANGLE SENSOR CHECK

Refer to GROUP 13C –  Troubleshooting. <4G9-MPI>

DETONATION SENSOR CHECK

Check the detonation sensor circuit if self-diagnosis code,
No. 31 is shown.

NOTE
For information concerning the self-diagnosis codes, refer to
GROUP 13C –  Troubleshooting <4G9-MPI>.

Plug gap gauge

Measurement direction