Fuel Injection Air (FIA) Inspection (3.5RL)

1. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Disconnect vacuum hoses individually from each injector. See Fig 1. Connect vacuum gauge and measure vacuum at each injector hose while idling.
2. If vacuum changes with engine speed, system is operating properly at this time. If vacuum does not change, check vacuum hoses for correct routing, leaks, breaks or clogging. If vacuum hoses are okay, check IAC valve. See DTC P1508: IDLE AIR CONTROL (IAC) VALVE CIRCUIT under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.5RL article. Also check Fast Idle Thermo Valve. See FAST IDLE THERMO VALVE - 3.5RL  under IDLE CONTROL SYSTEM. Check intake manifold passage for clogs. Repair or replace components as necessary.

Fig 1: Identifying Fuel Injection Air Control System (3.5RL Shown; 3.2TL Similar)

Courtesy of AMERICAN HONDA MOTOR CO., INC.