Intake Air By-Pass (IAB) Control Valve Inspection

Check valve shaft for binding and sticking, and ensure movement is smooth. Turn engine off. Ensure tab on IAB control valve contacts stop. See Fig 1 . Start engine and allow to idle. Ensure tab of IAB control valve contacts full-close screw. If any fault is found, clean linkage and shafts using carburetor cleaner. If problem still exists after cleaning, disassemble intake manifold and inspect IAB valve assembly.

Fig 1: Identifying Intake Air By-Pass Valve Linkage (Prelude)

Courtesy of AMERICAN HONDA MOTOR CO., INC.