Mitsubishi Pajero Pinin 1999, Workshop Manual

Page: 249 / 919

ENGINE ELECTRICAL ±
Ignition System
16-27
IGNITION SYSTEM
GENERAL INFORMATION
This system is equipped with four ignition coils with
built-in power transistors for each of the cylinders.
Interruption of the primary current flowing in the
primary side of an ignition coil generates a high
voltage in the secondary side of the ignition coil.
The high voltage thus generated is applied to the
spark plugs to generate sparks.
The engine-ECU turns the 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 and the crank angle
sensor. 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 running at high altitudes,
the ignition timing is slightly advanced to provide
optimum performance. Furthermore, if knocking
occurs, the ignition timing is gradually retarded until
knocking ceases.
SYSTEM DIAGRAM
Engine-
ECU
Air flow sensor
Barometric pressure sensor
Intake air temperature sensor
Engine coolant temperature
sensor
Accelerator pedal position
switch
Camshaft position sensor
Crank angle sensor
Ignition switch-ST
Detonation sensor
Vehicle speed sensor
Inhibitor switch
Ignition switch
Battery
Ignition coil
Spark plug
Cylinder No.
To tachometer
4
3
2
1
A/T-ECU