Turbochargers - INGENIUM I4 2.0L Diesel 240PS Engine Only

There are two turbochargers fitted to the engine. A Low Pressure (LP) turbocharger and a High Pressure (HP) Variable Geometry Turbine (VGT).

Variable Geometry Turbine Vane Actuator 

The Variable Geometry Turbine (VGT) is the High Pressure (HP) turbocharger. The VGT is an integral part of the exhaust manifold and is used mainly during engine light load and low speed operation.

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An integral bracket on the HP compressor cover locates the VGT vane actuator. The rotary motion from the VGT vane actuator is transmitted into the turbine housing by a lever mechanism and actuator rod. Within the turbine housing a ring rotates to control the position of all VGT vanes.

The VGT vane actuator comprises a 12V Direct Current (DC) motor which operates a worm drive to move the actuator arm to adjust the angular position of the turbocharger vanes.

The Powertrain Control Module (PCM) controls the output to the VGT vane actuator motor using a Pulse Width Modulation (PWM) output. The VGT vane actuator also provides the PCM with a positional feedback signal to determine the pitch angle of the vanes. An angular position sensor in the motor is provided with a reference voltage by the PCM. The position sensor returns a ground and a signal proportional to the actuator position.

The variable vanes in the turbocharger can be used to increase the energy available to the turbine wheel which in turn provides the compressor with more energy. This greatly assists the increase in charge air pressure at low engine speeds.

For additional information, Refer to: TURBOCHARGER

Low Pressure Turbocharger 

The Low Pressure (LP) turbocharger is located on the top of the exhaust manifold and is used mainly during engine high load and speed conditions.

The LP turbocharger has a vacuum operated wastegate valve control actuator to limit the maximum speed of operation to prevent overspeed and overboost. When open, the wastegate valve diverts exhaust gas (and hence energy) around the turbine and into the exhaust.

The wastegate valve control actuator is controlled by an Electronic Vacuum Regulating Valve (EVRV). The EVRV controls the vacuum supplied to the wastegate valve control actuator to operate the wastegate valve. The Powertrain Control Module (PCM) controls the operation of the EVRV. There is no feedback to the PCM from the turbocharger or the EVRV.

To manage the transition from the High Pressure (HP) Variable Geometry Turbine (VGT) to the LP turbocharger, the LP turbocharger contains a vacuum operated wastegate valve. The wastegate valve works in conjunction with the passive Compressor Bypass Valve (CBV). The wastegate valve is actuated by the larger of the two vacuum actuators mounted on the LP compressor cover. The wastegate valve modulates a flap valve similar to the wastegate valve between the HP VGT and the LP turbocharger. By opening this valve, exhaust gas is allowed to flow around the HP stage and into the LP stage. The wastegate valve actuator has no electrical connections, therefore there are no feedback signals.

Electronic Vacuum Regulating Valve Locations 

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The upper Electronic Vacuum Regulating Valve (EVRV) controls the vacuum actuator for the Turbine Shut-Off Valve (TSOV). The lower EVRV controls the Turbine Bypass Valve (TBV) vacuum actuator.

Switching between Turbochargers 

There are two mechanisms of switching between the High Pressure (HP) Variable Geometry Turbine (VGT) and the Low Pressure (LP) turbocharger:

• One is the operation of the Turbine Shut-Off Valve (TSOV)., which is vacuum controlled by the lower of the two Electronic Vacuum Regulating Valve (EVRV).
• The second is the operation of the Turbine Bypass Valve (TBV) and the passive Compressor Bypass Valve (CBV). The CBV operates on differential pressure within the LP turbocharger itself and has no mechanical or electrical control.

For additional information, Refer to: TURBOCHARGER