TOYOTA PRIUS 2001 Service Repair Manual

ENGINE ± 1NZ-FXE ENGINE
165EG12
Camshaft
Valve Lifter
Valve
171EG12
Camshaft Sprockets
Timing
Chain
Chain Guide
Oil Jet
Crankshaft
Sprocket Chain
Tensioner
Chain
Tension
Arm 50
3. Intake and Exhaust Valve and Valve Lifter
Valve lifters with shimless valve adjustment have been adopted for weight reduction.
The adjustment of the valve clearance is accomplished by selecting and replacing the appropriate valve
lifters.
Narrower valve stems have been adopted to reduce the intake and exhaust resistance and for weight reduc-
tion.

Specifications  mm (in.)
Item
Intake ValveExhaust Valve
Face Diameter30.5 (1.2)25.5 (1.0)
Stem Diameter5.0 (0.20)5.0 (0.20)
4. Timing Chain
A roller timing chain with an 8.0 mm pitch has
been adopted to make the engine more compact
and reduce chain noise.
A material which has excellent wear resistance
has been selected for the timing chain to im-
prove reliability.
The timing chain is lubricated by engine oil
from an oil jet.
Chain tensioner, chain tension arm and chain
guide are established to reduce the engine noise
and friction loss.

ENGINE ± 1NZ-FXE ENGINE
171EG13
Spring
Plunger
Cam
Cam Spring Check Ball
171EG32171EG31
Service Hole for
Chain Tensioner
Oil Pump
Front ViewBack View51
5. Chain Tensioner
The chain tensioner uses a spring and oil pres-
sure to maintain proper chain tension at all
times.
The chain tensioner suppresses noise generated
by the chain.
A ratchet type half-back mechanism is used.
6. Timing Chain Cover
A single-piece, aluminum die-cast timing chain cover that entirely seals the front portion of the cylinder
block and the cylinder head has been adopted.
A service hole for the chain tensioner has been provided in the timing chain cover to improve serviceabili-
ty.

ENGINE ± 1NZ-FXE ENGINE
182EG08
182EG09
MAIN OIL HOLE
RELIEF
VA LV E
RELIEF
VA LV E
OIL FILTER
OIL PUMP
OIL STRAINER
CRANKSHAFT
JOURNAL
CONNECTING
RODOIL JET
PISTON OIL JET
TIMING CHAINCHAIN
TENSIONER
CYLINDER HEAD
CAMSHAFT TIMING
OIL CONTROL VALVE
FILTER
INTAKE
CAMSHAFT
JOURNALEXHAUST
CAMSHAFT
JOURNAL
CAMSHAFT TIMING
OIL CONTROL VALVE
VVT-i
OIL PAN 52
LUBRICATION SYSTEM

The lubrication circuit is fully pressurized and all oil passes through an oil filter.

A trochoid gear type oil pump, which is driven directly by the crankshaft, has been provided in the front
of the cylinder block.

The oil filter has been installed diagonally downward from the side of the cylinder block to improve ser-
viceability.

ENGINE ± 1NZ-FXE ENGINE
182EG10
171EG17
From Heater
To Heater
To Radiator
From Radiator
Water Pump
Cylinder Head
Heater Core
Throttle Body
Radiator Cylinder Block Bypass
Passage
Water Pump
Thermostat53
COOLING SYSTEM
1. General

The cooling system is a pressurized, forced-circulation type.

A thermostat with a bypass valve is located on the water inlet housing to maintain suitable temperature
distribution in the cooling system.

The flow of the engine coolant makes a U-turn in the cylinder block to ensure a smooth flow of the engine
coolant.

The radiator for the engine and the A / C condenser have been integrated to minimize the space they occupy
in the engine compartment.

ENGINE ± 1NZ-FXE ENGINE
182EG11
Radiator
Condensor
RadiatorCondensor
Cutout 54
2. Radiator
The radiator for the engine and the A / C condenser have been integrated to minimize the space they occupy
in the engine compartment. Cutouts have been provided between the radiator and condenser sections to pre-
vent the transfer of heat between the two sections.

ENGINE ± 1NZ-FXE ENGINE
182EG12
A ± A Cross Section Throttle Control Motor
AA
Throttle Position SensorReturn Spring
Opener Spring
182EG13
Vacuum Port55
INTAKE AND EXHAUST SYSTEM
1. Throttle Body

The adoption of the ETCS-i has realized excellent throttle control.

The ISC system and cruise control system are controlled comprehensively by the ETCS-i.

The ETCS-i, which drives the throttle valve through a DC motor that is controlled by the ECM, thus doing
away with a throttle link to connect the accelerator pedal to the throttle valve, has been adopted.

The throttle control motor is provided with a return spring that closes the throttle valve.

An opener spring is provided on the throttle position sensor side. This spring opens the throttle valve slight-
ly when the engine is stopped to prevent the throttle valve from sticking and to improve the engine's restart-
ability.

A warm coolant passage is provided below the throttle body to prevent the throttle valve from freezing
during cold temperatures.
2. Intake Manifold

Because it is not necessary to improve the in-
take air efficiency through inertial intake due to
the adoption of the Atkinson cycle, the length
of the intake pipe of the intake manifold has
been shortened, and furthermore, the intake
pipes for cylinders #1 and #2, as well as for #3
and #4, have been integrated midstream to
achieve a large-scale weight reduction.
In addition, the throttle body has been oriented
downflow in the center of the surge tank to
achieve a uniform intake air distribution.

A vacuum port has been provided for the Toyo-
ta HC adsorber and catalyst system.

ENGINE ± 1NZ-FXE ENGINE
182EG14
182EG15
Ball Joints
Main Mufflar
TWC
TWC with HC Adsorber
182EG16
Actuator
HC Adsorber
Bypass Valve
TWC 56
3. Exhaust Manifold

A ball joint has been adopted for coupling the
exhaust manifold to the front pipe in order to
improve reliability.

A stainless steel exhaust manifold is used for
weight reduction.
4. Muffler
General

A ball joint has been adopted for coupling the exhaust manifold to the exhaust pipe and the exhaust pipe
to the main muffler to achieve a simple configuration and improved reliability.

The ceramic walls in the front TWC (Three-Way Catalytic Converter) have been decreased in thickness
and increased in density from the conventional models.
By decreasing the thermal capacity in this manner, it becomes easier to heat the catalyst and the catalyst's
exhaust cleansing performance is improved.

A Toyota HCAC (HC Adsorber and Catalyst) system has been adopted to improve the clean emission
performance of the exhaust gases when the temperature of the TWC is low.
Toyota HCAC System
a) General
This system provides HC adsorber coaxially to the TWC to improve the clean emission performance of
the exhaust gases when the temperature of the TWC is low.
b) Construction
This system consists of HC adsorber, TWC, actuator, bypass valve.

ENGINE ± 1NZ-FXE ENGINE
182EG17
182EG18
Cold Engine or Scavenging Mode
Warm Engine
Exhaust Gas57
c) Operation
Before the engine is started, the bypass valve remains open. When the engine is started, the ECM outputs
a signal to the VSV (for HC adsorber and catalyst system), which is applying a vacuum to the actuator.
As a result, the bypass valve closes.
Immediately after the engine has started, the exhaust gases pass through the HC adsorber in which HC
adsorbed and stored for a certain time (until the temperature of the HC adsorber rises). And prevent the
HC emitted from the tail pipe when the temperature of the TWCs are low.
After the TWC has warmed up, the VSV closes to the bypass valve to open. Then, as the temperature
of the rear TWC rises, the temperature of the HC absorber that surrounds it also rises, and the HC starts
to be desorbed, and cleaned by the TWC.
Furthermore, this system activates the VSV after the HC adsorber is warmed up and triggerd by decelera-
tion condition, the bypass valve is closed in order to scavenge the HC that remains in the HC adsorber.

ENGINE ± 1NZ-FXE ENGINE
182EG38
Injector
Delivery Pipe
Pressure Regulator
Fuel Tank Fuel Filter
Fuel Pump 58
FUEL SYSTEM
1. Injector
A compact 12-hole type injector has been adopted to improve the atomization of fuel.
2. Fuel Returnless System
This system is to reduce the evaporative emission. As shown below, integrating the pressure regulator and
fuel filter with the fuel pump assembly made it possible to discontinue the return of fuel from the engine area
and prevent temperature rise inside the fuel tank.
3. Quick Connector
Quick connector has been adopted to connect the fuel pipe with the fuel hose to improve serviceability.

ENGINE ± 1NZ-FXE ENGINE
182EG19
Air CleanerIntake Air Chamber
VSV (for EVAP)
ECM
VSV (for Purge Flow
Switching Valve)
Charcoal Canister
Vapor Pressure
Sensor
VSV (for Canister Closed Valve) Fuel Inlet Pipe Fuel: Vapor
: Fuel59
4. ORVR System
The ORVR (On-Board Refueling Vapor Recovery) is a system that uses a charcoal canister, which is provided
onboard, to recover the fuel vapor that is generated during refueling. This reduces the discharge of fuel vapor
into the atmosphere.
5. Fuel Tank
General
To reduce the amount of fuel vapor generated when the vehicle is parked, during refueling, or while driv-
ing, a vapor reducing fuel tank system has been adopted.
This system provides a vapor reducing fuel tank that expands or contracts in accordance with the volume
of the fuel in the fuel storage area in the fuel tank. By thus reducing the space in which fuel can evaporate,
the generation of fuel vapor is minimized.
Along with the provision of the vapor reducing fuel tank whose size fluctuates in the fuel tank, the fuel
gauge and the fuel pump have been provided in the sub tank. For this reason, a direct-acting fuel gauge
has been adopted.
NOTE:At low ambient temperatures, the capacity of the vapor reducing fuel tank is reduced as it is
made of resin (When the outside temperature is at ±10C (14F) the size of the tank will be re-
duced by approximate 5 liters).