ENGINE - 2AZ-FXE ENGINE
025EG30Y
Control Valve Close
Exhaust
Gas
Low Engine Speed
Control Valve Open
Middle to High Engine Speed
EG-24
2-Way Exhaust Control System
2-way exhaust control system is used. This system reduces the back pressure by opening and closing a
variable valve that is enclosed in the main muffler, thus varying the exhaust gas pressure.
The valve opens steplessly in accordance with the operating condition of the engine, thus enabling a
quieter operation at lower engine speeds, and reducing back pressure at higher engine speeds.
1) Construction
The control valve is enclosed in the main muffler. When the exhaust gas pressure overcomes the spring
pressure, the control valve opens steplessly in accordance with the exhaust gas pressure.
2) Operation
a. When Control Valve is Closed (low engine speed)
Since the pressure in the main muffler is low, the control valve is closed. Hence exhaust gas does not
pass the bypass passage, and exhaust noise is decreased in the main muffler.
b. When Control Valve is Open (middle to high engine speed)
The valve opens as the engine speed and the back pressure in the muffler increase. This allows a large
volume of exhaust gas to pass the bypass passage, thereby substantially decreasing the back pressure.