Mitsubishi MOTORS Lancer 2004, Workshop Manual

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IGNITION SYSTEM
ENGINE ELECTRICAL
16-30
IGNITION SYSTEM
GENERAL INFORMATION
M1163000100294
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 <M/T> or engine-A/T-ECU <A/T>
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 <M/T> or engine-A/T-ECU <A/T>
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
AK101074
Air flow sensor
<4G6>
MAP sensor <4G1>
Intake air temperatur
sensor
Engine coolant
temperature sensor
Camshaft position
sensor
Crank angle sensor
Barometric pressure
sonsor <4G6>
Detonatoin sensor
Ignition switch-ST
Engine-A/T-
ECU <A/T>
Engine-ECU
<M/T>
Ignition coil B
Cylinder No.
2 3 4
AG
1
Spark plug
Ignition coil A
Ignition
switch
Battery