Wastegate: Description and Operation

Turbocharger Mounting Nuts & Wastegate Servo Location:

The wastegate is located in the exhaust stream in the turbocharger housing. It controls the amount of exhaust pressure that is allowed to act on the turbine impeller. If the wastegate is closed, as in full throttle applications, full turbo boost is developed because all of the exhaust pressure is acting on the turbine impeller. If the wastegate is open, as in deceleration conditions, the exhaust pressure is allowed to bleed out to the exhaust system and no exhaust pressure acts on the turbine impeller. If exhaust pressure does not act on the turbine impeller, the compressor impeller will not turn, and turbo boost will not be developed.

The wastegate is controlled by the wastegate solenoid. The wastegate solenoid is an electronically controlled vacuum switching solenoid that controls the vacuum cirucit to the wastegate. The wastegate solenoid controls wether vacuum is allowed to actuate the wastegate, or wether vacuum is bled to the atmosphere. The following is a list of inputs the engine controller uses to determine when the wastegate solenoid should be ENERGIZED:

^ Throttle Position Sensor
^ Vehicle Distance (Speed) Sensor
^ Knock (Detonation) Sensor
^ Manifold Absolute Pressure (MAP) Sensor
^ Oxygen Sensor