Intake Air By-Pass Control Valve (Prelude)
CAUTION:
DO NOT adjust Intake Air ByPass (IAB) control valve full-close screw. It is factory preset.
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 control valve does not function properly, clean linkage and shafts using carburetor cleaner. If problem still exists after cleaning, disassemble intake manifold and inspect IAB valve assembly. See INTAKE MANIFOLD in appropriate article in ENGINES.