Page 155 - Manual_Polaris_RZR_ProXP-20-21

ENGINE / COOLING SYSTEM

INTAKE / EXHAUST SYSTEM
INTAKE / TURBO SYSTEM OVERVIEW

CAUTION
The turbocharger / exhaust system generates extreme heat and house rotating parts which can cause severe injury
and burns. Never touch any part of the turbocharger / exhaust system while the engine is running or until the engine
has been shut off and been allowed to sufficiently cool. Do not allow objects such as clothing, hair or body parts to
come into contact with or enter the compressor or turbine housing while the engine is running.

The turbocharger uses the energy of expanding exhaust gases exiting the engine to power a turbine and compressor. 3
Intake air is drawn into the compressor impeller and compressed before entering the engine. The intake compressor is
connected by a common shaft with the exhaust turbine. The shaft’s bearings are lubricated with engine oil.

Because of the precise manufacturing tolerances and shaft balancing, turbocharger disassembly is never
recommended. Never attempt to remove carbon build-up from the turbine blades.

The ambient pressure sensor relays the absolute outside air pressure to the ECU. The ECU uses this information to
determine the vehicle’s operating altitude.
The boost pressure sensor is located on the boost duct just before the throttle body. The ECU uses this sensor to
determine the actual absolute charged air pressure within the intake system and if boost pressure is too high, the ECU
will control the boost control solenoid to move the actuator to open the wastegate. No boost pressure is being
generated at idle so the boost pressure sensor should read close to barometric pressure.
The manifold pressure sensor senses the air pressure that is going into the engine.

The boost control valve allows the ECU to control the amount of boost pressure within the induction system. Boost
control is accomplished by pulsing the valve at different frequencies (pulse width modulate) depending on the amount
of boost pressure within the induction system. If the ECU determines that the targeted boost pressure has been
obtained, the ECU will trigger the pulse valve so that a certain level of compressor pressure is routed to the wastegate
actuator. Doing so activates the wastegate so that a proportion of exhaust gas bypasses the turbine. The boost control
valve vents to atmosphere when building boost. If the vent hose to atmosphere is plugged, an underboost code will
set.

The wastegate actuator is a mechanical device that houses a bellows, pre-load spring, and actuator arm. The
wastegate actuator is responsible for opening and closing the turbocharger’s internal wastegate door. When the door
is closed, all of the engine’s exhaust gases are routed to the turbine. This action increases turbine speed and boost
pressure. When the door is opened, some exhaust gas is allowed to immediately exit into the exhaust system,
bypassing the turbine. This action decreases turbine speed and boost pressure. If the wastegate actuator arm is
removed or disabled, the vehicle will go into limp home mode. if the actuator arm is out of adjustment, codes will set.

The Blow Off/Dump Valve help prevent turbo compressor load surging. When the throttle is suddenly released, intake
pressure is released through the dump valve to help the turbo spool back up when throttle is depressed. A change of
approximately .25 bar (3.6 PSI) sensed at the dump valve will cause it to open. The dump valve is normally open at
idle.

9930583 R01 - 2020-2021 RZR PRO XP / XP 4 Service Manual 3.11
© Copyright Polaris Industries Inc.