Boost Control System

Turbocharger Wastegate:

PURPOSE

The Boost Control System Controlls boost to prevent Engine damage.

OPERATION

The amount of turbocharger boost is limited to a maximum of 56 kPa (8.1 psi) by the wastegate and actuator. Under normal to moderate loads, the wastegate valve is closed and the intake air pressure changes in accordance with the engine rpm and the amount of exhaust gas. Under heavy loads, the intake air pressure in the air inlet duct reaches 56 kPa (8.1 psi), the pressure acts on the diaphragm and overcomes the force of the spring within the actuator, and the wastegate valve opens the bypass passage. As a result, the flow of exhaust gas applied to the turbine wheel drops, the rpm of the turbine wheel drops, and the boost pressure drops accordingly.
If the actual intake manifold pressure reaches 77 kPa (11 psi) and the calculated intake manifold pressure (calculated from the amount of intake air and engine speed) reaches a predetermined level, the fuel injection will be cut to prevent engine damage. Under this condition the turbo boost gauge will be indicating in the red sector of the gauge.