Gasoline Engine Air Intake Control System


The air intake control system is divided into two air cleaner inlets, and one of these inlets is provided with a valve, which is opened and closed to attain suitable air intake efficiency in accordance with the engine speed. This reduces the intake air noise in the low-speed range.
1. Construction
This system consists of the air intake control valve unit in the air cleaner inlet, the VSV (Vacuum Switching Valve) to control the vacuum which is the power source, and the check valve to prevent atmospheric air from flowing into the air intake chamber.
2. Operation
When the engine is running in the low- to mid-speed range, the engine ECU closes the air intake control valve. This causes an air intake on just one side, which reduces the air intake noise. When the engine is running in the high-speed range, the engine ECU opens the air intake control valve to allow air to be taken in from the two air inlets to improve the air intake efficiency.
The following systems are also controlled by the engine ECU.
1. Fuel octane judgement
Depending on the model, the engine ECU determines the octane rating of the gasoline being used from the engine knocking signal of the knock sensor and then switches its internal ignition map to “premium” or “regular” to match the fuel being used.
2. ECT OD cut-off control system
To maintain good drivability and acceleration performance, the engine ECU sends an OD cut-off signal to the ECT ECU based on the signals from the water temperature sensor and vehicle speed sensor to prevent the automatic transmission from shifting into overdrive. In addition, in several engines the engine ECU sends the 3rd-gear cut-off signal to the ECT ECU.
3. EGR cut-off control system
This system shuts off the EGR (Exhaust Gas Recirculation) to maintain drivability when the engine is warming up, during high-speed driving, etc.
4. T-VIS (Toyota-Variable Induction System)
A valve is provided on one of the two intake manifolds of each cylinder to close the valve during low engine speeds and open the valve during high engine speeds. This improves engine performance in both the engine low- and high-speed ranges.
5. SCV (Swirl Control Valve) system
A valve is provided on one of the two intake ports of each cylinder to close the valve during low engine speeds and open the valve during high engine speeds in order to improve engine performance in both the engine lowand high-speed ranges. In addition, the other intake port has been given a shape so that its cross-sectional area is gradually decreased as it moves forward to increase the flow speed of the intake air passing through here. This causes the intake air to swirl in the cylinder increasing combustion efficiency and improving fuel efficiency in the low-speed range.
6. Turbocharging pressure control system
By controlling the boost pressure applied to the actuator for the waste gate valve, this system controls the air intake turbocharging pressure. This improves engine power while maintaining engine durability thus improving drivability.
7. Supercharger control system
This system controls everything related to the supercharger, such as starting and stopping the supercharger, and opening and closing the air bypass when the supercharger is stopped.
8. EHPS (Electro-Hydraulic Power Steering) control system
This control is only provided in vehicles with an EHPS that uses an electric motor to drive the vane pump. This system controls the vane pump motor speed. For example, the vane pump is stopped to ensure the startability or prevent the engine from stalling when the engine is cold or the engine speed is extremely low.

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