LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 1988 >> GL 2D Hatchback, 1.8 5 >> Repair and Diagnosis >> Engine Performance >> System >> SPFI CEC System >> Operation >> By-Pass Air Control System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

By-Pass Air Control System

An air passage by-passing throttle valve is provided to route air directly into lower course of throttle valve. Air control valve is located in middle of air passage.

Air control valve controls amount of air at engine starting, idle speed, etc. Air control valve is driven by signals from SPFI control unit and regulates opening of by-pass to maintain idle speed at set value.

CAUTION: Never connect battery in reverse polarity because SPFI control unit will be destroyed instantly and fuel injector and other parts will be damaged in just a few minutes more. Also, DO NOT disconnect battery terminals while engine is running because a large electrical surge will be generated. This surge, may cause damage to electrical components.
Fig 1: Checking Throttle Sensor Resistance
G61887Courtesy of SUBARU OF AMERICA, INC.