Page 27 of 2000

ENGINE - 2AZ-FE ENGINE EG-30
ENGINE CONTROL SYSTEM
1. General
The engine control system for the 2AZ-FE engine has the following systems.
System
Outline
SFI
Sequential Multiport
Fuel InjectionAn L-type SFI system directly detects the intake air volume with a hot-wire
type mass air flow meter.
The fuel injection system is a sequential multiport fuel injection system.
ESA
Electronic Spark
AdvanceIgnition timing is determined by the ECM based on signals from various sensors.
The ECM corrects ignition timing in response to engine knocking.
ETCS-i
Electronic
Optimally controls the throttle valve opening in accordance with the amount of
accelerator pedal effort and the condition of the engine and the vehicle.
Electronic
Throttle Control
System-intelligent
(See page-43)A linkless-type is used, without an accelerator cable.
An accelerator pedal position sensor is provided on the accelerator pedal.
A non-contact type throttle position sensor and accelerator pedal position
sensor are used.
VVT-i
Va r i a b l e Va l v e
Timing-intelligent
(See page EG-48)
Controls the intake camshaft to an optimal valve timing in accordance with the
engine condition.
Air-fuel Ratio
Sensor, Oxygen
Sensor Heater
ControlMaintains the temperature of the air-fuel ratio sensor or oxygen sensor at an
appropriate level to realize accuracy of detection of the oxygen concentration in
the exhaust gas.
Air Conditioning
Cut-off ControlBy turning the air conditioning compressor ON or OFF in accordance with the
engine condition, drivability is maintained.
Cooling Fan Control
(See page EG-52)Radiator cooling fan operation is controlled by signals from ECM based on the
engine coolant temperature sensor signal and the condition of the air
conditioning operation.
Fuel Pump Control
(See page EG-53)Fuel pump operation is controlled by signal from the ECM.
The fuel pump is stopped when the SRS driver’s and front passenger’s airbags
are deployed.
Evapotative Emission
The ECM controls the purge flow of evaporative emissions (HC) in the canister
in accordance with engine conditions.
Evapotative Emission
Control
(See page EG-54)Approximately five hours after the ignition switch has been turned OFF, the
ECM operates the canister pump module to detect any evaporative emission
leakage occurring in the EVAP (evaporative emission) control system through
changes in the 0.02 in. leak pressure.
Charging Control
(See page EG-65)The ECM regulates the charging voltage of the generator in accordance with the
driving conditions and the charging state of the battery.
(Continued)
Page 29 of 2000

ENGINE - 2AZ-FE ENGINE
01MEG04Y
SENSORSACTUATORS
MASS AIR FLOW METER
INTAKE AIR TEMPERATURE
SENSOR
ENGIEN COOLANT
TEMPERATURE SENSOR
THROTTLE POSITION
SENSOR
CRANKSHAFT POSITION
SENSOR
CAMSHAFT POSITION
SENSOR
ACCELERATOR PEDAL
POSITION SENSOR
AIR-FUEL RATIO SENSOR
(Bank 1, Sensor 1)
HEATED OXYGEN SENSOR
(Bank 1, Sensor 2)
KNOCK SENSOR
COMBINATION METER
Vehicle Speed Signal
IGNITION SWITCH
Ignition Signal
Starter Signal
PA R K / N E U T R A L P O S I T I O N
SWITCH
TRANSMISSION CONTROL
SWITCH
CRUISE CONTROL SWITCHVG
THA
THW
VTA1
VTA2
NE
G2
VPA
VPA2
A1A
OX1B
KNK1
SPD
IGSW
STA
D, 2, L
R, P, N
3
CCSECM#10
#20
#30
#40
IGT1 IGT4
IGF1
M
OC1
FC
HA1A
HT1BSFI
No.1 INJECTOR
No.2 INJECTOR
No.3 INJECTOR
No.4 INJECTOR
ESA
IGNITION COIL
with IGNITER
SPARK PLUGS
ETCS-i
THROTTLE CONTROL
MOTOR
VVT-i
CAMSHAFT TIMING OIL
CONTROL VALVE
FUEL PUMP CONTROL
CIRCUIT OPENING
RELAY
AIR-FUEL RATIO AND
HEATED OXYGEN SENSOR
HEATER CONTROL
AIR-FUEL RATIO SENSOR
HEATER (Bank1, Sensor1)
HEATED OXYGEN SENSOR
HEATER (Bank1, Sensor2)
EG-32
2. Construction
The configuration of the engine control system in the 2AZ-FE engine is shown in the following chart.
(Continued)
Page 31 of 2000
ENGINE - 2AZ-FE ENGINE
01MEG09Y
Accelerator Pedal
Position Sensor
Generator
MIL
DLC3Park / Neutral
Position Switch
Ignition
Switch
Circuit Opening RelayECM
Battery
Throttle
Position
Sensor
Throttle
Control
Motor
Purge VSVMass Air Flow Meter
Intake Air Temperature
Sensor
Camshaft Position
Sensor
Camshaft
Timing
Oil Control
Va l v e
Ignition Coil
with Igniter
Injector
Knock Sensor
Engine
Coolant
Temperature
Sensor
Crankshaft Position
Sensor
Canister
Filter
Fuel Pump
Canister Pump Module
Ve n t Va l v e
Leak Detection Pump
Canister Pressure SensorTWCs
Heated Oxygen Sensor
(Bank 1, Sensor 2)
Air-fuel Ratio Sensor
(Bank 1, Sensor 1) EG-34
3. Engine Control System Diagram
Page 32 of 2000
ENGINE - 2AZ-FE ENGINE
01MEG31Y
DLC3
Accelerator Pedal
Position Sensor
Mass Air Flow Meter
(Built-in Intake Air
Temperature Sensor)
VSV (for EVAP)
Battery Current
Sensor
Fuel Pump
Canister Pump Module
Ve n t Va l v e
Leak Detection Pump
Canister Pressure Sensor
ECM
Heated Oxygen Sensor
(Bank 1, Sensor 2) Air Fuel Ratio Sensor
(Bank 1, Sensor 1)
Camshaft Timing
Oil Control ValveInjectorKnock Sensor
Ignition Coil with Igniter
Throttle Position
Sensor
Camshaft Position
Sensor
Water Temperature
Sensor
Crakshaft Position
SensorEG-35
4. Layout of Main Components
Page 33 of 2000
ENGINE - 2AZ-FE ENGINE EG-36
5. Main Components of Engine Control System
General
The main components of the 2AZ-FE engine control system are as follows:
Component
OutlineQuantity
ECM32-bit CPU1
Mass Air Flow MeterHot-wire Type1
Crankshaft Position Sensor (Rotor Teeth)Pick-up Coil Type (36-2)1
Camshaft Position Sensor (Rotor Teeth)Pick-up Coil Type (3)1
Throttle Position SensorNon-contact Type1
Accelerator Pedal Position SensorNon-contact Type1
Knock SensorBuilt-in Piezoelectric Element Type
(Flat Type)1
Air-fuel Ratio Sensor
(Bank 1, Sensor 1)Type with Heater
(Planar Type)1
Heated Oxygen Sensor
(Bank 1, Sensor 2)Type with Heater
(Cup Type)1
Injector12-hole Type4
ECM
The 32-bit CPU of the ECM is used to increase the speed for processing the signals.
Page 34 of 2000

ENGINE - 2AZ-FE ENGINE
00REG21Y
D13N11
Air-fuel
Ratio
SensorA1A+
(3.3V)
A1A -
(2.9V)ECMHeated
Oxygen
SensorOX1B
EX1BECM
Air-fuel Ratio Sensor Circuit Heated Oxygen Sensor
: Air-fuel Ratio Sensor
: Heated Oxygen Sensor
Air-fuel Ratio Sensor Data
Displayed on Hand-held
Te s t e r4.2
2.2
11 (Rich) 14.7 19 (Lean)0.11
Heated Oxygen
Sensor Output (V)
Air-fuel RatioEG-37
Air-fuel Ratio Sensor and Heated Oxygen Sensor
1) General
The air-fuel ratio sensor and heated oxygen sensor differ in output characteristics.
Approximately 0.4V is constantly applied to the air-fuel ratio sensor, which outputs an amperage that
varies in accordance with the oxygen concentration in the exhaust emission. The ECM converts the
changes in the output amperage into voltage in order to linearly detect the present air-fuel ratio. The
air-fuel ratio sensor data is read out by the hand-held tester.
The output voltage of the heated oxygen sensor changes in accordance with the oxygen concentration
in the exhaust emission. The ECM uses this output voltage to determine whether the present air-fuel
ratio is richer or leaner than the stoichiometric air-fuel ratio.
Page 35 of 2000

ENGINE - 2AZ-FE ENGINE
271EG45
Alumina
Dilation Layer
Alumina
Platinum
Electrode
Sensor Element (Zirconia)Heater AtmospherePlatinum
ElectrodeHeater
Atmosphere
Sensor Element
(Zirconia)
Planar Type Air-fuel Ratio Sensor Cup Type Heated Oxygen Sensor
204EG54
Temperature Sensing
Element
Platinum Hot-wire
ElementAir FlowIntake Air
Temperature
Sensor EG-38
2) Construction
The basic construction of the air-fuel ratio sensor and heated oxygen sensor is the same. However, they
are divided into the cup type and the planar type, according to the different types of heater construction
that are used.
The cup type sensor contains a sensor element that surrounds a heater.
The planar type sensor uses alumina, which excels in heat conductivity and insulation, to integrate a
sensor element with a heater, thus realizing the excellent warm-up performance of the sensor.
Warm-up Specification
Sensor TypePlanar TypeCup Type
Warm-up TimeApprox. 10 sec.Approx. 30 sec.
Mass Air Flow Meter
The compact and lightweight mass air flow meter, which is a plug-in type, allows a portion of the intake
air to flow through the detection area. By directly measuring the mass and the flow rate of the intake air,
the detection precision is ensured and the intake air resistance is reduced.
This mass air flow meter has a built-in intake air temperature sensor.
Page 98 of 2000

ENGINE - 2GR-FE ENGINE EG-102
System
Outline
Air-fuel Ratio Sensor and
Oxygen Sensor Heater
ControlMaintains the temperature of the air-fuel ratio sensor or oxygen sensor at an
appropriate level to increase accuracy of detection of the oxygen
concentration in the exhaust gas.
Evaporative Emission
Control
[See page EG-131]
The ECM controls the purge flow of evaporative emission (HC) in the
canister in accordance with engine conditions.
Approximately five hours after the ignition switch has been turned OFF,
the ECM operates the canister pump module to detect any evaporative
emission leakage occurring in the EVAP (evaporative emission) control
system through changes in the EVAP control system pressure.
Engine ImmobilizerProhibits fuel delivery and ignition if an attempt is made to start the engine
with an invalid ignition key.
Diagnosis
[See page EG-132]When the ECM detects a malfunction, the ECM diagnoses and memorizes
the failed section.
Fail-safe
[See page EG-133]When the ECM detects a malfunction, the ECM stops or controls the engine
according to the data already stored in the memory.