1.9T Turbocharger Operation »

SYSTEM OVERVIEWS

1.9T Turbocharger @
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Before learning how to repair the 1.9T Turbocharger System, it is important to understand:

- The components used to control the turbocharger system.
- When the components are used.
- How the turbocharger system is tested.

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Variable Vane System

The 1.9T Turbocharged diesel engine
does not use a Wastegate, as the 1.8T
gasoline engine does.

Instead of the Wastegate, a circular series
of moveable vanes are used to control the
airflow across the turbine blades.

This is called the Variable Vane System.

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Variable Vane System

As the linkage moves, the circular
ring is turned.

The turning of the circular ring causes
the vanes to change their angle.

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Variable Vane System

Changing the angle of the vanes determines
the speed of exhaust air flowing over the
turbine.

A shallow vane angle compresses the exhaust
air, speeding it up. When this fast-moving air
hits the turbine, it causes the turbine to spin
faster.

Asteep vane angle does not provide much
pressure. The air flows across the turbine
blades at normal exhaust speed.

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‘Stoop vane angle
Large inlet cross-section
of exhaust gas flow
Direction of
rotation

of adjusting ring

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Variable Vane System

The ability to change the speed of the
exhaust gases allows for a high charge
pressure at low rpm.

[Exhaust gas|
pressure

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Turbine

wheel
Vane

Charge
pressure

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Steep Vanes

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System Operation

At idle, the vanes are moved to a shallow

angle. +
This allows the fastest possible maximum ‘Sheep Vones

charge for pressure build-up.
N75 is at a low duty cycle for this condition,
allowing vacuum to control the Wastegate
Actuator Diaphragm that regulates vane
angle.

At low throttle conditions, the vanes are
moved toward a steep angle.

N75 is at a higher duty cycle, allowing
atmospheric pressure to the servo.

Any continued increase in boost is
created by exhaust gas pressure.

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Ince-coater

Westegate Bypess
Foguator Valve N75,

Intake Manifold Fap (aways cpen when the engine's running)

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Throne Position

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System Operation ome
When the throttle is first depressed, the ¢
duty cycle drops, allowing vacuum to be '

applied to the servo. Shallow Vanes

The vanes move to a shallow angle, which Wostogate Bypass

speeds up the exhaust flow to increase Regulator Valve N75

boost.

As boost pressure continues to increase,
the ECM, J248, increases duty cycle to
N75 to allow atmospheric pressure to
the servo.

This allows the vanes to move to a
steep angle.

Any continued increase in boost is
created by exhaust gas pressure.

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cle

Vacuurn Purp

Imake Manilold ap (always open when the engine is nie)

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‘Treonle Position
Sensor

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System Operation

When the throttle is first depressed, the —
duty cycle drops, allowing vacuum to be
applied to the servo.

The vanes move to a shallow angle, which ‘Wastogate Bypass
speeds up the exhaust flow to increase Regulator Vane N75
boost.

As boost pressure continues to increase,
the ECM, J248, increases duty cycle to
N75 to allow atmospheric pressure to
the servo.

This allows the vanes to move to a
steep angle.

Any continued increase in boost is
created by exhaust gas pressure.

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Vacinam Purp

Invake Manifold Flap (always opan when the engine is nznirg)

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System Testing

There are three methods of testing the operation of the turbocharger system.
- Testing with the VAS 5051/5052
- Resistance check of N75
~ Actuator operation

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Testing with the VAS 5051/5052

The VAS 5051 has tests in both Guided Fault Finding, where applicable, and in
Vehicle Self-Diagnosis to check the operation of N75.

The VAS 5052 can check the operation of N75 through Vehicle Self-Diagnosis.

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Resistance check of N75

The correct operation of N75 can be
determined by checking resistance.

Refer to the Repair Information for the
correct procedures and specifications.