Note: This system is not used in Lexus PX330 models 2004 and later. At the time of going to press, information on the availability of spare parts for this system was not available.
1. The air intake control system reduces intake noise in the low-speed range and increases power in the high-speed range. It includes a vacuum switching valve (VSV), an actuator, and an air intake control valve. The air intake control system is located in the fresh air intake duct leading to the air filter housing, on the filter housing side. (Do not confuse the fresh air intake duct with the air intake duct that connects the air cleaner housing to the throttle body. The fresh air intake duct will carry fresh air to the air cleaner housing.) The VSV valve and actuator are located on top of the air intake duct, and the air intake control valve is located directly below them in the air duct. The fresh air intake duct is divided into two chambers: an upper chamber and a lower chamber.
2. When the engine is running in the low to mid-range speed range, the PCM activates the VSV, which acts on the actuator, which moves the air intake control valve to close one chamber inside the fresh air intake duct. This reduces the cross-sectional area of the fresh air intake duct and reduces intake noise.
3. When the engine is running at high speed, the PCM turns off the VSV valve, which disengages the actuator that opens the air intake control valve, allowing fresh air to enter both chambers of the fresh air intake duct. This increases the cross-sectional area of the fresh air intake duct and improves intake efficiency.