2001 TOYOTA PRIUS Service Repair Manual

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).

ENGINE ± 1NZ-FXE ENGINE
182EG20
182EG21
From Air Cleaner To Intake Air Chamber
When the Tank is Full
From Air CleanerTo Intake Air Chamber
When the Tank is EmptyVapor Reducing Fuel Tank 60

System Diagram 
Fuel Gauge
A direct-acting fuel gauge has been provided in the sub tank.
This gauge consists of a pipe that is surrounded by a coil, and a float in the pipe moves up and down with
the fluctuation of the fuel level.
A magnet is attached to the back side of the float. The up or down movement of the float causes a change
in the magnetic field. The flow of current through the coil creates a potential difference, and the resultant
voltage is transmitted to the meter ECU. For details, see page 146 (Meter Section).

ENGINE ± 1NZ-FXE ENGINE
165EG25
Camshaft
Position
Sensor
Crankshaft
Position
Sensor
Various
SensorsG2
NEECM
IGT1
IGT2
IGT3
IGT4
IGF+BIgnition Coil
(with Igniter)
No.1
Cylinder
No.2
Cylinder
No.3
Cylinder
No.4
Cylinder61

IGNITION SYSTEM
1. General
A DIS (Direct Ignition System) has been adopted. The DIS improves the ignition timing accuracy, reduces
high-voltage loss, and enhances the overall reliability of the ignition system by eliminating the distributor.
The DIS in 1NZ-FXE engine is an independent ignition system which has one ignition coil (with igniter) for
each cylinder.
2. Ignition Coil
The DIS provides 4 ignition coils, one for each cylinder. The spark plug caps, which provide contact to the
spark plugs, are integrated with an ignition coil. Also, an igniter is enclosed to simplify the system.
3. Spark Plug
Iridium-tipped spark plugs have been adopted to realize a 60,000-mile (100,000 km) maintenance-free op-
eration. Their center electrode is made of iridium, which excels in wear resistance. As a result, the center
electrode is made with a smaller diameter and improved the ignition performance.

CHARGING AND STARTING SYSTEM
MG1 and MG2 (Motor Generator No.1 and 2) have been adopted in the charging system, and the convention-
al generator has been discontinued.
Furthermore, due to the adoption of MG1 for the starting system, the conventional starter has been discontin-
ued.