Idle Speed Control (Isc) System - Mazda 626 1989 Workshop Manual

4B
ISC SYSTEM

IDLE SPEED CONTROL (ISC) SYSTEM

To improve idle smoothness, the ISC system controls the intake air amount by regulating the bypass
air amount that passes through the throttle body.
This system consists of the BAC valve and the control system.
The BAC valve consists of the air valve which functions only when the engine is cold (below 50°C
( 1 2 2 °F)) and the ISC valve which works throughout the entire engine speed range.
76G04C-077