Ignition System; Ignition Control System - BOMBARDIER Johnson 90 Service Manual

ENGINE CONTROL SYSTEM
IGNITION SYSTEM
IGNITION SYSTEM
The ignition system used by the 90/115/140 is a fully transistorized, electronic microcomputer timing
advanced type. This system is totally battery powered, with the ECM controlling all ignition timing func­
tions. The ignition system is composed of the ignition coil, spark plug and components for system control
(ECM, sensor, switch, etc.). When the ignition switch is "ON", battery voltage (12V) is applied to the oír­
cuit as shown in the illustration. At the calculated time of ignition, the transistor in the ECM turns "OFF",
breaking the ground circuit. In this way, a mutual induction high voltage occurs in the ignition coil second­
ary side and spark is generated.
Battery
ECM
CPU
11
lgnition coil
11
Sparl< ''""
(Volt cige)
1
1-Spark timing
l
®
terminal voltage (Time)
lgnition Control System
OUTLINE
Sensors at specific points on the engine monitor current engine conditions and send signals to the ECM.
Based on these signals, the ECM determines the optimum ignition timing and raleases voltage to the
ignition coils.
Baslc sensors
CvM
MAPsensor:
lnforms ECM of intake manifold pressure.
lgnition timing is determined by
-
CKP sensor:
a digital map designed in
relation to intake manifold
lnforms ECM of engine speed and crankshaft angle.
pressure and engine speed.
Compensating sensors
i'r
Cyllnder temperature sensor:
:
1
lgnition timing compensation
lnforms ECM of cylinder temperature.
Others
,-- - ..
CTP switch:
. . .
ISignal
I ISignal
1
lnforms ECM of throttle position (open/ closed).
~
lgnltlon switch:
'
'
lnforms ECM of "START" signal.
, . _
1
lgn.coil
11
lgn.< oil
1
ECM
Spark plug
• •
11
3-11