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ENGINE — 1MZ-FE ENGINE36
ENGINE CONTROL SYSTEM
�DESCRIPTION
The construction and functions of the new 1MZ-FE engine includes the following modifications and addi-tions in comparison with the 1MZ-FE engine installed on the ’98 ES300 as the base:
System Outline RX300 ’98 ES300
SFISequentialMultipot FuelInjection
The newly adopted L-type SFI system directly mea-sures the intake air flow by means of the hot-wire typeair flow meter.
� �
The newly adopted air assisted fuel injection system fa-cilitates fuel atomization for the improvement of emis-sion control performance and fuel economy.
� �
ESAElectronic SparkAdvance
Ignition timing is determined by the ECM based on sig-nals from various sensors. Corrects ignition timing inresponse to engine knocking.
� �
The torque control correction during gear shifting hasbeen used to minimized the shift shock. � �
2 knock sensors are used to further improve knockdetection. � �
IAC(Idle Air Control)
A rotary solenoid type IAC system controls the firstidle and idle speeds.
�(1-Coil Type)
�(2-Coil Type)
VVT-iVariable ValveTiming-intelligent
Controls the intake camshaft to an optimal valve timingin accordance with the engine condition. � —
ACISAcoustic ControlInductionSystem
This system changes the intake manifold length over inthree stages according to the engine rpm and throttlevalve opening to improve the performance at all enginespeeds.
� —
Active ControlEngine Mount
The damper characteristic of the front engine mount in-sulator is varied to reduce idling vibration. � —
A/F Sensor andOxygen SensorHeater Control
Maintain the temperature of the A/F sensor and oxygensensors at an appropriate level to increase accuracy ofdetection of the oxygen concentration in the exhaustgas.
� �
Air Fuel RatioFeedback control
The precision air fuel ratio feedback control has beenimproved through the adoption of the air-fuel ratio sen-sor and oxygen sensor.
� �*
EngineImmobilizer
Prohibits fuel delivery and ignition if an attempt ismade to start the engine with an invalid ignition key. � �
Function tocommunicate withmultiplexcommunicationsystem
Communicates with the body ECM, A/C ECU, etc., onthe body side, to input/output necessary signals. � —
*: Calfornia only
ENGINE — 1MZ-FE ENGINE 37
�CONSTRUCTION
The configuration of the engine control system in the new 1MZ-FE engine for RX300 is as shown in thefollowing chart. Shaded portions differ from the 1MZ-FE engine for ’98 ES300.
W
STA
PRE
CF
PS
STP
PTNK
TRCENG
TC
SIL
SENSORS
MASS AIR FLOW METER
CRANKSHAFT POSITION SENSOR(Crankshaft Angle Signal)
VVT CAM ANGLE SENOSR
ENGINE COOLANT TEMP. SENSOR
ACTUATORS
ECM
Right Bank
Left Bank
INTAKE AIR TEMP. SENSOR
THROTTLE POSITION SENSOR(Throttle Position Signal)
IGNITION SWITCH
VEHICLE SPEED SENSOR
COMBINATION METER
HEATED OXYGEN SENSOR
KNOCK SENSOR(Right Bank & Left Bank)
NEUTRAL START SWITCH
STARTER RELAY
A/C COMP PRESSURE SWITCH
COOLING FAN RELAY
POWER STEERING OIL PRESSURE SWITCH
STOP LIGHT SWITCH
VAPOR PRESSURE SENSOR
TRAC ECU*
DATA LINK CONNECTOR 1
DATA LINK CONNECTOR 3
TRANSPONDER KEYAMPLIFIER
AIR FUEL RATIO SENSOR(Right Bank & Left Bank)
EFI MAIN RELAY
EFI
No. 1 ~ No. 6 INJECTOR
ESA
IGNITION COIL with IGNITER
SPARK PLUGS
IAC
CONTROL VALVE
FUEL PUMP CONTROL
CIRCUIT OPENING RELAY
AIR CONDITIONING CONTROL
AIR CONDITIONING ECU
HEATED OXYGEN SENSOR HEATER
VVT-i CONTROL
VVT-i Solenoid VSV RH
EVAP CONTROL
VSV
VAPOR PRESSURE CONTROL
VSV
VVT-i Solenoid VSV LH
MALFUNCTION INDICATOR LAMP
AIR FUEL RATIO SENSOR HEATER(Right Bank & Left Bank)
MULTIPLEX COMMUNICATION SYSTEM
BODY ECU
AIR CONDITIONER/METER ECU
BATTERY
VG
NE
VV1
VV2
THW
THA
VTA1
IGSW
STA
SPD
OXS
KNKR
KNKL
NSW
TXCTRXCK
CODE
AFR
AFL
+B
#10~#60
IGT1~6
RSO
FC
ACMG
HTS
OC1
OC2
EVAP1
TPC
IMLD
BATT
MPX1
MPX2
HAFRHAFL
THEFT DETERRENT INDICATOR LIGHT LAMP*2
*: Applicable only to vehicles equipped with the TRAC System.
ENGINE — 1MZ-FE ENGINE38
�ENGINE CONTROL SYSTEM DIAGRAM
157EG20
ABS Unit
Meter UnitFuel PressureControlRelay
StartSwitch
FuelPressureRegulator
Vehicle Speed Signal
MIL
Fuel PumpBattery
A/CAmplifier
DLC3
Park/Neutral Position Switch
Electronic ControlledTransmissionSolenoid Valves
Stop Light SwitchElectric Load Switch
ECMORVRBreatherLine
VSV (for EVAPPurge Control)
PressureSensorVSV(PressureControl)
VSV (for AcousticControl InductionSystem)
IAC Valve
Intake Air Temp.Sensor
Mass AirFlow Meter
Throttle Position Sensor
A/F Sensor
Camshaft PositionSensor
Oil Control Valve
Warm-Up-TWC ECT Sesnor
RPM Sensor Knock Sensor
Warm-Up-TWCA/F Sensor
TWC
CamshaftPositionSensor
Injector
Oil Control Valve(for VVT Control)
EI
Fuel Filter
Heated Oxygen Sensor
ENGINE — 1MZ-FE ENGINE 39
�LAYOUT OF COMPONENTS
157EG21
Knock Sensor
IAC Valve
Throttle Position Sensor
O2 Sensor
ECM
Cam Position Sensor
Air Flow Meter
OCVCam Position Sensor
A/F Sensor
Crank Position Sensor
InjectorWater TemperatureSensor
Ignition Coilwith Built-inIgnite
ENGINE — 1MZ-FE ENGINE40
�VVT-i CONTROL SYSTEM
General
� This system controls the intake camshaft valve timing so as to obtain balance between the engine output,fuel consumption and emission control performance. The actual intake side valve timing is fed backby means of the cam position sensor for constant control to the target valve timing.
157EG22
Throttle Position Sensor
OCV (RH bank)
Cam Position Sensor (RH bank)
OCV (LH bank)
Cam Position Sensor (LH bank)
Water Temperature SensorECM
AirFlow Meter
Crank Position Sensor
157EG23
ECM
Target Valve Timing
Actual Valve Timing
Correction
Feedback
OCV
Duty Control
Crank Position Sensor
Air Flow Meter
Throttle Position Sensor
Water Temperature Sensor
Cam Position Sensor
ENGINE — 1MZ-FE ENGINE 41
�CONSTRUCTION AND FUNCTIONS
Construction
The camshaft on the exhaust side is driven by the timing belt from the crankshaft pulley, and the camshafton the intake side is driven by the gear train from the exhaust side.The camshaft drive gear (exhaust side) is combined with a scissors gear to reduce the gear noise due totorque variation. The camshaft driven gear (intake side) is integrated with the VVT-i actuator to vary theintake camshaft valve timing.
157EG22
157EG24
Crankshaft TimingPulley
Timing BeltDrive Gear(scissors gear)
Driven gear(VVT-i Actuator)
Exhaust Camshaft
Intake Camshaft
Valve timingVarying Portion
Intake Camshaft
VVT-i Actuator
Cam Position Sensor
Exhaust Camshaft
CrankshaftCam Position Sensor Cam Position Sensor
VVT-i Actuator
ENGINE — 1MZ-FE ENGINE42
The ECM distributes the pressure generated by the oil pump into the advance side and retard side by meansof the OCV (oil control valve) installed on the side wall of the cylinder head for adjusting the pressuresbefore and after the VVT-i controller vane to control the intake camshaft phase.
VVT-i Controller
This controller consists of the housing driven from the exhaust camshaft and the vane coupled with theintake camshaft.The oil pressure sent from the advance or retard side path at the intake camshaft causes rotation in theVVT-i controller vane circumferential direction to vary the intake valve timing continuously.
157EG25
Driven Gear
Housing (fixed on driven gear) Vane Seal
Vane Portion(fixed on intake camshaft)
This illustration shows theangle advance state.
OCV (Oil Control Valve)
The oil control valve spool position is varied to constantly obtain the optimum valve timing accordingto the duty signal sent from the ECM.The latest timing position is set by the spring force while the engine is stopped.
157EG26
VVT-i Pulley TimingAdvance Chamber
VVT-i Pulley TimingRetard Chamber
Spool Valve
Connector
PlungerCoilDrainDrain
Oil PressureSpring
Sleeve
ENGINE — 1MZ-FE ENGINE
VVT-i Actuator
ECM
Fluid Pressure
Advance Signal
Duty Ratio
Retard Signal
Duty Ratio
Hold Signal
Duty Ratio
ECM
Fluid Pressure
ECM
Fluid Pressure
Vane(fixed on intakecamshaft)
157EG27 157EG28
157EG29 157EG30
157EG31 157EG32
Rotating Direction
157EG36
157EG37
157EG35
43
Operation (Hydraulic System)
The OCV selects the path to the VVT-i actuator according to the advance, retard or hold signal from theECM. The VVT-i actuator rotates the camshaft in the timing advance or retard position or holds it accordingto the position where the fluid pressure is applied.
Operation OCV drive signal Description
Adv
ance
When the OCV is positionedas illustrated at left by the ad-vance signal from the ECM,the resultant fluid pressure isapplied to the timing advanceside vane chamber to rotatethe camshaft in the timing ad-vance direction.
Del
ay
When the OCV is positionedas illustrated at left by the re-tard signal from the ECM, theresultant fluid pressure is ap-plied to the timing retard sidevane chamber to rotate thecamshaft in the timing retarddirection.
Hol
d
The ECM calculates the tar-get timing angle according tothe traveling state to performcontrol as described above.After setting at the target tim-ing, the valve timing is heldby keeping the OCV in theneutral position unless thetraveling state changes.This adjusts the valve timingat the desired target positionand prevents the engine oilfrom running out when it isunnecessary.
ENGINE — 1MZ-FE ENGINE
IN
�IN
IN �
IN�
IN �
IN
IN
Latest timing
Latest timing
Latest timing
To retard side
To retard side
To advance side
To advance side
EX
EX
EX
EX
EX
EX
EX
44
ECM
In proportion to the engine speed, intake air volume, throttle position and coolant temperature, the ECMsearches an optimal valve timing under each driving condition and control the camshaft timing oil controlvalve. In addition, ECM uses signal from the VVT sensors and the crankshaft position sensor to detectthe actual valve timing, thus performing feedback control to achieve the target valve timing.
� Operation During Various Driving Condition �
151EG74
Eng
ine
Loa
d
Range 4
Range 1 Engine Speed
Range 2
Range 3
Range 5
Full Load Perfomance
Operation state Range Valve timing Objective Effect
During idling 1Eliminating overlap to re-duce blow back to the in-take side
Stabilized idling rpmBetter fuel economy
At light load 2Decreasing overlap toeliminate blow back to theintake side
Ensured engine stability
At mediumload
3Increasing overlap to in-crease internal EGR forpumping loss elimination
Better fuel economyImproved emission con-trol
In low tomedium speedrange withheavy load
4Advancing the intake valveclose timing for volumetricefficiency improvement
Improved torque in lowto medium speed range
In high speedrange withheavy load
5Retarding the intake valveclose timing for volumetricefficiency improvement
Improved output
At lowtemperatures —
Eliminating overlap to pre-vent blow back to the in-take side for reduction offuel increase at low temper-atures, and stabilizing theidling rpm for decreasingfast idle rotation
Stabilized fast idle rpmBetter fuel economy
Upon starting/stopping theengine
—Eliminating overlap toeliminate blow back to theintake side
Improved startability
ENGINE — 1MZ-FE ENGINE 45
�SFI (Sequential Multipot Fuel Injection) SYSTEM
� The L-type SFI system is adopted to adjust fuel injection volume by directly measuring the intake airflow with a hot-wire type air flow meter.
� An air assist type fuel injection system is adopted to improve emission control and fuel economy befacilitating fuel atomization.
Air-Fuel Ratio and Feedback Control
As illustrated below, the conventional oxygen sensor is characterized by a sudden change in its outputvoltage at the threshold of the stoichiometric air-fuel ratio (14.7 to 1). In contrast, the air-fuel ratio sensoroutput a voltage that is approximately proportionate to the existing air-fuel ratio by converting the oxygendensity to the voltage. As a result, the detection precision of the air-fuel ratio has been improved.
151EG30
151EG31
Air-FuelRatio Sensor
AF+
AF−3.0V
3.3V
ECM
Air-Fuel Ratio Sensor
(V)4.2
(V)1
0.12.2
11 14.7 19
Oxygen SensorA
ir-Fu
el R
atio
Sen
sor
Out
put
Oxy
gen
Sens
orO
utpu
t
Air-Fuel Ratio
Output Characteristics
The precision of the air-fuel feedback control has been improved through the adoption of the air-fuel ratiosensor. As illustrated below, if the existing air-fuel ratio diverts from the stoichiometric air-fuel ratio, theconventional oxygen sensor used to correct the air-fuel ratio at a constant proportion. However, with theair-fuel ratio sensor, the ECM can determine the extent of diversion from the stoichiometric air-fuel ratioand execute an immediate correction.
151EG32
Rich�
StoichiometricAir-Fuel Ratio
�Lean
InjectionVolume
Previous(Oxygen Sensor)
New(Air FuelRatio Sensor)
DisorderNew
Previous
Correction at aConstant Proportion
Immediate Correction
ENGINE — 1MZ-FE ENGINE46
�ACIS (ACOUSTIC CONTROL INDUCTION SYSTEM) CONTROL
General
The ECM intake control valve is opened/closed according to the engine rpm and throttle valve openingto vary the intake manifold length in three stages for improving the torque under heavy load in the mediumspeed range.
Operation
Relationships between engine rpm and throttle valve opening
1 Engine speed below 2,700 rpm and throttle valve opening at 30 degrees or more (Low speed range withheavy load)
2 Engine speed between 2,700 and 3,700 rpm and throttle valve opening at 30 degrees or more (Mediumspeed range with heavy load)
3 Engine speed up to 3,700 rpm with throttle valve opening at 30 degrees or less, and full range withengine speed above 3,700 rpm (Idling range, light load range and high speed range)
1 Low speed range with heavy load
2 Medium speed range with heavy load
3 Idling range, light load range and high speed range
157EG10
157EG11
157EG12
Engine rpm
2700r/min 3700r/min
1 2 3
3 3
30°
157EG33
Thr
ottle
Val
ve O
peni
ng