Mazda 323 1988 Workshop Manual page 229

IDLE SPEED CONTROL (ISC) SYSTEM
4A
IDLE SPEED CONTROL (ISC) SYSTEM
Throttle sensor
\
Atmospheric
pressure sensor
Engine control unit
E/L control valve
Water
sensor
OUTLINE
To improve idle smoothness, the ISC system controls the intake air amount detected by the air flow
meter by regulating the bypass air amount that passes through the throttle body, and thereby helps
the engine to maintain a steady idle speed.
This system consists of the BAC valve and the control system.
The BAC valve consists of the air valve which functions only during cold engine conditions and the
ISC valve which works throughout the entire engine speed range.
4A-29