Boost Control

The boost control system determines a desired boost. Active control occurs when the desired boost is above base boost where base boost is defined as that boost that results when the wastegate vent solenoid is not venting (circuit off).

The following conditions may result in underboost.

• One or more wastegates stuck open
• Large conduit leak between compressor and throttle

The following conditions may result in overboost.

• One or more wastegates stuck closed
• One or more control hoses leaking/disconnected between wastegate diaphragm and wastegate vent solenoid.
• Wastegate vent solenoid stuck in vent position
• Control hoses to wastegate vent solenoid swapped.
• Hose between boost volume and wastegate vent solenoid disconnected.
• Not-yet-detected Turbocharger Boost sensor in-range failure.

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The boost control system computes a desired boost based on operating conditions. Via the wastegate pneumatic solenoid valve, it varies the boost pressure limit to achieve its desired boost level (measured by the TCB-A sensor). The air charge control regulates the throttle to control the intake manifold pressure (MAP).