Air Intake Control System: Description: Notes

NOTE: For information on Accord, Civic and Prelude carbureted systems, refer to THERMOSTATIC AIR CONTROL article.

System supplies air for all engine needs. It consists of air cleaner, air intake pipe, throttle body, Electronic Air Control Valve (EACV), fast idle mechanism and intake manifold. On all models, a resonator control system in the air intake pipe provides additional silencing as air is drawn into system.

Accord and Prelude EFI models are also equipped with a by-pass control system. This system consists of 2 separate air paths for air induction, allowing the ECU to select the proper intake path length for different engine operating conditions. A long path is used for high torque at low RPM. A short path is used for high power at high RPM. ECU controls by-pass valves in intake manifold through use of a by-pass control solenoid (2 used on Legend) and a by-pass valve control diaphragm.

Civic models with throttle body injection are equipped with a tandem control system. The tandem valve is employed to improve fuel atomization. This is accomplished by regulating venturi vacuum (to tandem valve actuating diaphragm) through an ECU controlled solenoid valve. Solenoid is energized and venturi vacuum is allowed to activate diaphragm when coolant temperature is greater than 160°F (70°C) or engine speed is greater than 1500 RPM (auto. trans.) or 2000-2800 RPM (man. trans.), depending upon atmospheric pressure. See Figure - Figure .