Note. This system is not used on 2004 and later Lexus PX330 models. At the time of preparing the book for publication, 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 rpm range and increases power in the high rpm range. It includes a vacuum switching valve (VSV), actuator and 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 side of the filter housing. (Do not confuse the fresh air intake duct with the intake duct that connects the air filter housing to the throttle body. The fresh air intake duct will drive fresh air into the air filter housing.) The VSV and actuator are located on top of the air intake duct, while the air intake control valve is located directly below them in the air duct. The fresh air intake duct is divided into two chambers: upper and lower.
2. When the engine is running in the low to medium range, the PCM activates the VSV, which acts on an actuator that 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 RPM, the PCM turns off the VSV, which turns off the actuator, which opens the air intake control valve, allowing fresh air to enter both chambers of the fresh air inlet air line. This increases the cross-sectional area of the fresh air intake duct and improves intake efficiency.