Theory Of Operation

The base Turbocharger boost pressure is managed by the mechanical Wastegate. The Wastegate is a mechanical valve that, when opened, allows exhaust gases to flow around the turbine. The Wastegate is spring loaded in the closed position. Boost pressure is applied to a diaphragm that works against the spring pressure of the Wastegate. When the force created by the boost pressure exceeds the spring force in the Wastegate, the valve opens. This limits boost pressure by limiting the speed of the Turbocharger. Boost pressure is applied against the spring pressure of the Wastegate to control the speed of the Turbocharger. The Wastegate Solenoid is Pulse Width Modulated (PWM) by the PCM and is located between the compressor and mechanical Wastegate. When opened by the PCM, the Wastegate Solenoid bleeds boost pressure away from the mechanical wastegate, this allows the PCM to increase boost pressure to a level higher than would be allowed by the mechanical wastegate alone. The system operates as follows; boost pressure is supplied to the Wastegate Solenoid through a hose connected to the compressor side of the Turbocharger. The Powertrain Control Module (PCM) varies the PWM signal to the Wastegate Solenoid to control the amount of boost pressure applied against the Wastegate. When more boost pressure is needed, the Wastegate Solenoid will direct more of the boost pressure to the clean air tube upstream of the Turbocharger and less against the Wastegate spring.