Mitsubishi MOTORS Eclipse 1997, Service Manual

Page: 405 / 540

Ignition System Engine
ENGINE ELECTRICAL
(Turbo) and Engine>
This system is provided with two ignition coils (A
and B) and two ignition power transistors (A and
B) for the No. 1 and No. 4 cylinders, and 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.
same the
IS
‘the V o l t a g e
thus generated is applied to the spark plugs of
No. 2 and No. 3 cylinders.
The engine control controls the two ignition
power transistors (A and B) to turn them alternately
ON and OFF. This causes the primary currents
in the ignition coils (A and B) to be alternately
interrupted and allowed to flow to fire the cylinders
in the order
The engine control module 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
crankshaft position sensor which is incorporated
in the It also detects the crankshaft
position in order to provide ignition at the most
appropriate timing in response to the engine
operation conditions.
‘the ignition
to provide optimum performance.
Furthermore, if knocking occurs, the ignition timing
is gradually retarded until knocking ceases.
lntakeairtemperaturesensor
Atmospheric pressure sensor
Engine coolant temperature sensor
Closed throttle position switch
.
position sensor
sensor
Engine
control
module
Vehicle speed sensor
Ignition power
transistor unit
I Ignition coil
Cylinder No.
1250
TSB Revision