2000 TOYOTA CAMRY engine

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NEW FEATURES Ð 5S-FNE ENGINE15
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 automatical-
ly 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.
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.
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 preventing the fuel tank from bursting due to the increase
in gas pressure.
The discharged CNG is guided under the floor through a vent tube and is released outside of the vehicle.
4. 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 prevent the CNG from flowing backward.
5. Manual Shutoff Valve
This valve is mounted below the vehicle floor.
When servicing the vehicle, this valve can be manu-
ally turned 90 degrees to shut off the main pipe.
167CN09

NEW FEATURES Ð 5S-FNE ENGINE 16
6. Fuel Filter
Mounted below the vehicle floor, the fuel filter re-
moves any moisture or oil from the fuel.
7. 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 km/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 associat-
ed with the expansion of the gas causes the fuel pressure regulator to be cooled excessively, exerting
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.
Oil
Separator
Water Passage
Fuel
Shutoff
Valve
Relief Valve
167CN24 167CN25167CN10

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NEW FEATURES Ð 5S-FNE ENGINE17
8. 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
167CN13
Discharge
ValveFuel Pressure Sensor
Fuel Temp. Sensor
Delivery Pipe
CNG
Fuel Shutoff
Valve
9. Injector
For the injection of fuel in the gaseous state, injectors that allow the flow of a large volume of fuel and
provide improved sealing performance have been adopted.
These injectors are actuated by the voltage (150V) that has been increased by the voltage booster circuit
provided in the ECM.
ECM
167CN14
167CN23
Rubber Sheet
12V
+B
Voltage
Booster
Circuit#10+
#10Injector

NEW FEATURES Ð 5S-FNE ENGINE 18
10. Fuel Temperatur and Pressure Sensor for Fuel Gage
A fuel temperature sensor that detects the temperature in the fuel tank is provided on the tank valve assembly.
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 215C to actuate the fuel gauge.
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 iridium-tipped spark plugs that have their metallic portion
plated.

Recommended Spark Plug 
DENSO
SK20R11-G
Plug Gap1.0 ± 1.1 mm (0.0394 ± 0.043 in.)
167CN15
: Plating Area
Iridium Tip
Platinum Tip 0.7 mm

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NEW FEATURES Ð 5S-FNE ENGINE19
ENGINE CONTROL SYSTEM
1. General
An engine control system based on the 5S-FE engine has been adopted. The knock sensor has been discontin-
ued 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
Sequential
A D-type SFI system is used, which indirectly detects
intake air volume by manifold absolute pressure sensor.
Sequential
Multiport Fuel
Injection
The fuel injection system is a sequential multiport fuel
injection system.
Ignition timing is determined by the ECM based on sig-
nals from various sensors.
ESA
Electronic Spark
AdvanceThe ECM corrects the ignition timing in response to en-
gine knocking in accordance with the signals received
from the knock sensor.
Ð
Advance
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 sup-
ply of fuel when the ignition switch is turned OFF or
during abnormal conditions (such as engine stalling,
SRS airbag deployed, etc.).
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 accu-
racy of detection of the oxygen concentration in the ex-
haust 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 emis-
sions (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
When the ECM detects a malfunction, the ECM diag-
noses and memorized the failed section.
DiagnosisThe diagnosis system includes a function that detects a
malfunction in the evaporative emission control sys-
tem.
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

NEW FEATURES Ð 5S-FNE ENGINE
(Continued)
PIM
NE
G
THW
THA
VTA
AF
#10+
#20
#30
#40
IGT1,
IGT2
IGF
RSD
EGR
OX2
HTAF
HT2
MGC
FUEL W
PSW
ELS
NSW
F/PS
A/C SW
ECM
STA
SPD
R,2,L
STP
#40+ #30+ #20+ #10
FUEL
20
2. Construction
The configuration of the engine control system in the 5S-FNE engine is as shown in the following chart.
SENSORS
MANIFOLD ABSOLUTE
PRESSURE SENSOR
CRANKSHAFT POSITION
SENSOR
CAMSHAFT POSITION
SENSOR
ENGINE COOLANT TEMP.
SENSOR
INTAKE AIR TEMP. SENSOR
THROTTLE POSITION SENSOR
IGNITION SWITCH
COMBINATION METER
wVehicle Speed Signal
AIR FUEL RATIO SENSOR
(Bank 1, Sensor 1)
HEATED OXYGEN SENSOR
(Bank 1, Sensor 2)
POWER STEERING OIL
PRESSER SWITCH
TAILLIGHT & REAR WINDOW
DEFOGGER SYSTEM
PARK/NEUTRAL POSITION
SWITCH
STOP LIGHT SWITCH
AIR CONDITIONING SWITCH
AIRBAG SENSOR ASSEMBLY
wFuel Cut-Off Signal
ACTUATORS
SFI
No. 1 INJECTOR
No. 2 INJECTOR
No. 3 INJECTOR
No. 4 INJECTOR
ESA
IGNITERS and
IGNITION COILS
SPARK PLUGS
IAC
CONTROL VALVE
EGR
VSV
AIR FUEL RATIO SENSOR
HEATER CONTROL
AIR FUEL RATIO SENSOR
HEATER
OXYGEN SENSOR HEATER
CONTROL
HEATED OXYGEN SENSOR
HEATER
AIRE CONDITIONING
CUT-OFF CONTROL
MAGNET CLUTCH RERAY
FUEL GAGE
LOW FUEL LEVEL WARNING
LIGHT

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NEW FEATURES Ð 5S-FNE ENGINE
TE1
BATT +B
BATTERYEFI MAIN RELAYFC
THCNG 1
PCNG 1VCNG 2
SIL
ECM
THCNG 2
PCNG 2VCNG 3
+B1
21
FUEL TEMP. SENSOR for
FUEL TANK
FUEL TEMP. SENSOR for
DELIVERY PIPE
FUEL PRESSURE SENSOR for
FUEL PIPE
FUEL PRESSURE SENSOR for
DELIVERY PIPE
DATA LINK CONNECTOR 1
FUEL CUT-OFF CONTROL
CIRCUIT OPENING RELAY
FUEL SHUTOFF VALVE for
FUEL TANK
FUEL SHUTOFF VALVE
for FUEL PRESSURE
REGULATOR
FUEL SHUTOFF VALVE for
DELIVERY PIPE
DATA LINK CONNECTOR 3

NEW FEATURES Ð 5S-FNE ENGINE 22
3. Engine Control System Diagram
Fuel Tank
167CN1 1
SpeedometerFuel Gage & Warning
MIL
DLC3
Airbag Sensor Assembly
ECM
Fuel Temp.
Sensor
Fuel Shutoff
ValveFuel
Pressure
Regulator
Fuel
Shutoff
Valve
Fuel
Pressure
Sensor
Camshaft
Position
Sensor
Air Fuel
Ratio Sensor
WU-TWC
Crankshaft Position
Sensor
Heated Oxygen Sensor
TWC Engine Coolant
Temp. Sensor Fuel Pressure
Sensor
Manifold
Absolute
Pressure
Sensor EGR Valve
EGR Vacuum
Modulator
VSV
(for EGR)Intake Air
Temp. Sensor
IAC Valve
Throttle
Position
Sensor
Manual Fuel
Shutoff
Valve
Fuel Filter
Fuel Temp. Sensor
Fuel Shutoff Valve
Coupler