Subaru 2002 Impreza Service Manual page 117

I
m
IGNITION CONTROL SYSTEM
Emission Control
(Aux.
Emission Control
Devices)
6. Ignition Control System
0
The ignition system is controlled by the ECM.
The ECM monitors the operating condition of the engine using the signals from the sensors and
switches shown below and determines the ignition timing most appropriate for each engine oper-
ating condition. Then it sends a signal to the ignitor, commanding generation of a spark at that
timing.
0
The ECM uses a preprogrammed map for a "closed-loop" control which provides its ignition tim-
ing control with excellent transient characteristics, i.e., highly responsive ignition timing control.
(1) Battery
(2) Ignition switch
(3) ECM
(4) Camshaft position sensor
(5) Crankshaft position sensor
NF0308
(6) Ignition coil and ignitor assembly
(7) Knock sensor
(8) Mass air flow and intake air temperature sensor
(9) Engine coolant temperature sensor
EC-9