TOYOTA CAMRY 2000 Service Owner's Manual

3
CAMRY ± NEW FEATURES
167CN05
WU-TWC
167CN06
TWCSub MufflerMain Muffler41
5. Intake and Exhaust System
Throttle Body
The throttle body is basically the same as that of the 5S-FE engine. However, to ensure the starting perfor-
mance at low temperatures, the air passage for the IAC (Idle Air Control) has been increased on the 5S-FNE
engine. The IAC valve is a 1-coil type with a built-in driver.
Exhaust Manifold
As in the California specification 5S-FE engine,
the stainless steel exhaust manifold and WU-
TWC (Warm Up Three-Way Catalytic Convert-
er) have been integrated to improve the warm-up
performance of TWC, thus reducing exhaust
emissions.
However, the 5S-FNE engine uses a catalytic
converter that has been designed exclusively for
the CNG application, in which the loading of the
noble metal has been increased.
Exhaust Pipe
1) General
To secure sufficient luggage compartment capacity, the main muffler has been relocated below the rear
seat. Furthermore, the muffler capacity has been increased.
A 2-way exhaust control system has been adopted to improve engine performance and reduce the exhaust
noise.
Similar to the WU-TWC, the TWC (Three-Way Catalytic Converter) has been designed exclusively for
the CNG application, in which the loading of the noble metal has been increased.

CAMRY ± NEW FEATURES
167CN07
Exhaust Gas
Control Valve
Control Valve: Low Engine Speed
: High Engine Speed
42
2) 2-Way Exhaust Control System
a. General
A 2-way exhaust control system reduces the back pressure by opening and closing two control valves
that are enclosed in the main muffler, thus verying the exhaust gas passage.
The valves open steplessly in accordance with the operating condition of the engine, thus enabling
a quieter operation at low engine speeds, and reducing back pressure at high engine speeds.
b. Operation
The control valves are closed at low engine speeds because the pressure in the main muffler is low.
Therefore, the exhaust gas flows as indicated by the black arrow below, thus reducing the exhaust noise.
The control valves open at high engine speeds because the exhaust gas pressure increased. Therefore,
the exhaust gas flows as indicated by the white arrow below to reduce the back pressure, thus improving
the engine's power output.

3
CAMRY ± NEW FEATURES
172CM14
Fuel
Pressure
SensorFuel Temp.
SensorFuel
Pressure
RegulatorFuel Shutoff ValveFuel Tank
Fuel Shutoff ValveRelief Valve
Inlet Check
Valve
Fuel Temp.
Sensor
Coupler
Tank Valve Assembly
Vent Tube Manual
Shutoff
Valve Oil
Separator
Fuel Shutoff Valve Injectors
Delivery Pipe Discharge
ValveFuel
Pressure
SensorFuel
Filter43
6. Fuel System
General
The compressed gas [maximum pressure approximately 250 kg / cm
2 (3600 psi, 24.8 MPa) @ 21C
(70F)] from the CNG fuel tank located in the rear section of the vehicle is routed via a fuel filter to the
engine compartment. The pressure of the fuel is then reduced to 8 kg / cm
2 (114 psi, 785 kPa).
A pressure regulator and injectors designed exclusively for CNG application have been adopted.
A fuel pressure sensor and a fuel temperature sensor that are used for the correction of the fuel injection
volume are located on the delivery pipe.
The fuel tank, pressure regulator, and the delivery pipe are provided with shutoff valves that shut off the
fuel when the ignition switch is turned OFF.
In addition, these valves shut off the fuel when the engine stalls, the SRS airbag is deployed, or the pres-
sure in the main pipe becomes abnormally low.
A fuel temperature sensor for the fuel gauge is mounted on the tank valve assembly, and a fuel pressure
sensor is mounted immediately upstream of the pressure regulator.

Fuel System Diagram 

CAMRY ± NEW FEATURES
167CN08
Tank Valve
AssemblyTank Band
Coil Springs
167CN26
Tank Valve AssemblyFuel
Temperature
Sensor 44
Fuel Tank
A fuel tank made with carbon fiber and alumi-
num lining has been adopted to prevent weight
increase.
Because the fuel tank expands along with the
increase in the pressure of the compressed gas,
the tank bands contain coil springs to accom-
modate the fluctuation in the perimeter of the
tank.
The fuel tank is provided with a tank valve as-
sembly.
Tank Valve Assembly
1) General
The tank valve assembly is mounted on the
tank and consists of a fuel shutoff valve, inlet
check valve, relief valve and two manual cut-
off valves.

3
CAMRY ± NEW FEATURES
172CM17
CloseOpen45
2) Fuel Shutoff Valve for Fuel Tank
This valve uses an solenoid valve. The main pipe that supplies compressed gas to the engine is connected
to this valve, which opens when the ignition switch is turned ON. If the engine stalls, this valve automati-
cally shuts off the fuel even if the ignition switch is turned ON. The valve reopens upon restarting the
engine.
Also, this valve shuts off the fuel if the SRS airbag is deployed in a collision or if the pressure in the main
pipe becomes abnormally low.
3) Inlet Check Valve
Connected to a filler pipe that guides the fuel that fills through the coupler, the inlet check valve shuts
off by the force of a spring and by the pressure of the gas in the tank.
During filling, the pressure of the filling gas opens the inlet check valve.
4) Relief Valve
A vent tube is connected to this valve.
If the fuel tank is exposed to an abnormally high temperature, this valve opens (by melting) to discharge
the CNG at a predetermined temperature, thus helping prevent the fuel tank from bursting due to the in-
crease in gas pressure.
The discharged CNG is guided under the floor through a vent tube and is released outside of the vehicle.
Coupler
The coupler allows the fuel to be filled when it is connected with a fuel filling nozzle. The coupler has a
built-in check valve to help prevent the CNG from flowing backward.
Manual Shutoff Valve
This valve is mounted below the vehicle floor.
When servicing the vehicle, this valve can be
manually turned 90 degrees to shut off the main
pipe.

CAMRY ± NEW FEATURES
167CN10
172CM15
Fuel
Shutoff
Valve
Water Passage
Oil SeparatorRelief Valve 46
Fuel Filter
Mounted below the vehicle floor, the fuel filter
removes any moisture or oil from the fuel.
Fuel Pressure Regulator
The fuel pressure regulator regulates the fuel pressure by reducing the pressure of the compressed natural
gas from the fuel tank to the fuel injection pressure, which is 8 kg / cm
2 (114 psi, 785 kPa).
Similar to the fuel shutoff valve for the fuel tank, a fuel shutoff valve is provided on the fuel inlet side
of the fuel pressure regulator to shut off the supply of fuel when the engine is stopped or during abnormal
conditions.
An oil separator that traps the moisture and oil in the fuel is provided on the low pressure side.
A built-in relief valve is provided to protect the parts located on the low pressure side.
While the fuel pressure is being reduced by the fuel pressure regulator, the Joule-Thomson effect
associated with the expansion of the gas causes the fuel pressure regulator to be cooled excessively, exert-
ing unfavorable influence on the rubber parts such as diaphragms and fuel hoses.
Therefore, to raise the gas temperature, a water passage is provided in the fuel pressure regulator to allow
the engine coolant to warm the regulator.

3
CAMRY ± NEW FEATURES
172CM13
Discharge
ValveFuel Pressure Sensor
Fuel Temp. SensorDelivery Pipe
CNG
Fuel Shutoff
Valve
Injector
167CN23
Rubber Sheet47
Delivery Pipe
A delivery pipe with a wide passage that enables a large volume of gas to flow responsively has been
adopted to minimize the pressure loss.
A fuel pressure sensor and a fuel temperature sensor that help correct the fuel injection volume are
mounted on the delivery pipe.
Similar to the fuel shutoff valves for the fuel tank and the fuel pressure regulator, a fuel shutoff valve is
provided on the fuel inlet side of the delivery pipe to shut off the supply of fuel when the engine is stopped
or during abnormal conditions.
To discharge the fuel out of the delivery pipe during service, a discharge valve is provided.
Injector
For the injection of fuel in the gaseous state, injectors that allow the flow of a large volume of fuel and pro-
vide improved sealing performance have been adopted.

CAMRY ± NEW FEATURES
172CM16
: Plating Area
Platinum Tip
48
Fuel Temperature and Pressure Sensor for Fuel Gage
A fuel temperature sensor that detects the temperature in the fuel tank is provided on the tank valve assem-
bly.
A fuel pressure sensor that detects the pressure in the fuel main pipe is provided immediately upstream of
the fuel pressure regulator.
The pressure and the temperature of the fuel are detected by these sensors and are input into the ECM.
These values are then converted by the ECM into the equivalent pressure at 21C to actuate the fuel gauge.
7. Ignition System
Because the spark plugs are susceptible to rust when used with natural gas, corrosion-resistant spark plugs
have been adopted. These spark plugs are the platinum-tipped spark plugs that have their metallic portion
plated.

Recommended Spark Plug 
DENSOPK20TR8-G
Plug Gap0.8 ± 1.0 mm (0.031 ± 0.39 in.)

3
CAMRY ± NEW FEATURES49
8. Engine Control System
General
An engine control system based on the 5S-FE engine has been adopted. The knock sensor has been discon-
tinued because natural gas has a high octane value and is less susceptible to knocking.
The engine control system of 5S-FNE and 5S-FE engines are compared below.
System
Outline5S-FNE5S-FE
SFI
Se
quential
A D-type SFI system is used, which indirectly detects
intake air volume by manifold absolute pressure sensor.Sequential
Multiport Fuel
InjectionThe fuel injection system is a sequential multiport fuel
injection system.
Ignition timing is determined by the ECM based on
signals from various sensors.
ESA
Electronic Spark
AdvanceThe ECM corrects the ignition timing in response to
engine knocking in accordance with the signals
received from the knock sensor.
Ð
dva ce
Torque control correction during gear shifting had been
used to minimize the shift shock.*1
IAC
(Idle Air Control)A rotary solenoid type IAC valve controls the fast idle
and idle speeds.(1-Coil Type
Built-in Driver)(2-Coil Type)
Fuel Pump ControlFuel pump operation is controlled by signal from the
ECM.Ð
Fuel Cut-Off
Control
The fuel shutoff valves for the fuel tank, fuel pressure
regulator, and delivery pipe are shut off to stop the
supply of fuel when the ignition switch is turned OFF or
during abnormal conditions (such as engine stalling,
SRS airbag deployed, etc.).
Ð
Injector ControlPrevents the frozen stuck of the injector to ensure the
startability of the engine at low temperature.Ð
Oxygen Sensor
and Air Fuel Ratio
Sensor
Heater ControlMaintains the temperature of the oxygen sensor and air
fuel ratio sensor at an appropriate level to increase
accuracy of detection of the oxygen concentration in the
exhaust gas.
*2
EGR Cut-Off
ControlCuts off EGR according to the engine condition to
maintain drivability of the vehicle and durability of the
EGR components.

Evaporative
Emission ControlThe ECM controls the purge flow of evaporative
emissions (HC) in the charcoal canister in accordance
with engine conditions.
Ð
Air Conditioning
Cut-Off ControlBy turning the air conditioning compressor ON or OFF
in accordance with the engine condition, drivability is
maintained.
*3*3
Diagnosis
When the ECM detects a malfunction, the ECM
diagnoses and memorized the failed section.
DiagnosisThe diagnosis system includes a function that detects a
malfunction in the evaporative emission control system.Ð
Fail-Safe
When the ECM detects a malfunction, the ECM stops or
controls the engine according to the data already stored
in memory.

*1: Only for Automatic Transaxle Model
*
2: Air fuel ratio sensor only for California specification model
*
3: The air conditioning magnet clutch controled by the ECM

CAMRY ± NEW FEATURES
No.4 INJECTOR
SPARK PLUGSIGNITERS and
IGNITION COILS
No.2 INJECTOR
No.1 INJECTOR
No.3 INJECTOR
SENSORS ACTUATORS
MANIFOLD ABSOLUTE
PRESSURE SENSORSFI PIM#10+
CRANKSHAFT POSITION
SENSORNE
CAMSHAFT POSITION
SENSORG
ENGINE COOLANT TEMP.
SENSORTHW
INTAKE AIR TEMP. SENSORTHA
THROTTLE POSITION SENSORVTA
COMBINATION METER
SPD
Vehicle Speed Signal
AIR FUEL RATIO SENSOR
(Bank 1, Sensor 1)AF
HEATED OXYGEN SENSOR
(Bank 1, Sensor 2)OX2
POWER STEERING OIL
PRESSER SWITCHPSW
TAILLIGHT & REAR WINDOW
DEFOGGER SYSTEMELS
IGNITION SWITCHSTA
PARK / NEUTRAL POSITION
SWITCHNSW
STOP LIGHT SWITCHSTP
AIRBAG SENSOR ASSEMBLY
F/PS
Fuel Cut-Off Signal
#10
#20+
#20
#30+
#30
#40+
#40
ESA
IGT1,
IGT2
IGF
CONTROL VALVEIACRSD
VSV EGREGR
AIR FUEL RATIO SENSOR
HEATER AIR FUEL RATIO SENSOR
HEATER CONTROLHTAF
HEATED OXYGEN SENSOR
HEATER OXYGEN SENSOR HEATER
CONTROLHT2
MAGNET CLUTCH RERAYAIRE CONDITIONING
CUT-OFF CONTROLMGC
FUEL GAGE
LOW FUEL LEVEL WARNING
LIGHT
ECM
AIR CONDITIONING SWITCHA/C SW
R, 2, L
FUEL
FUEL W
50
Construction
The configuration of the engine control system in the 5S-FNE engine is as shown in the following chart.
(Continued)