ENGINE — 1MZ-FE ENGINE
36
ENGINE CONTROL SYSTEM
JDESCRIPTION
The construction and functions of the new 1MZ-FE engine includes the following modifications and additions in comparison with the 1MZ-FE engine installed on the ’98 ES300 as the base:
System
SFI
Sequential
Multipot Fuel
Injection
ESA
Electronic Spark
Advance
Outline
The newly adopted L-type SFI system directly measures the intake air flow by means of the hot-wire type
air flow meter.
RX300
’98 ES300
f
f
The newly adopted air assisted fuel injection system facilitates fuel atomization for the improvement of emission control performance and fuel economy.
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f
Ignition timing is determined by the ECM based on signals from various sensors. Corrects ignition timing in
response to engine knocking.
f
f
The torque control correction during gear shifting has
been used to minimized the shift shock.
f
f
2 knock sensors are used to further improve knock
detection.
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f
IAC
(Idle Air Control)
A rotary solenoid type IAC system controls the first
idle and idle speeds.
VVT-i
Variable Valve
Timingintelligent
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f
(1-Coil Type)
(2-Coil Type)
Controls the intake camshaft to an optimal valve timing
in accordance with the engine condition.
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—
ACIS
Acoustic Control
Induction
System
This system changes the intake manifold length over in
three stages according to the engine rpm and throttle
valve opening to improve the performance at all engine
speeds.
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—
Active Control
Engine Mount
The damper characteristic of the front engine mount insulator is varied to reduce idling vibration.
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—
A/F Sensor and
Oxygen Sensor
Heater Control
Maintain the temperature of the A/F sensor and oxygen
sensors at an appropriate level to increase accuracy of
detection of the oxygen concentration in the exhaust
gas.
f
f
Air Fuel Ratio
Feedback control
The precision air fuel ratio feedback control has been
improved through the adoption of the air-fuel ratio sensor and oxygen sensor.
f
f*
Engine
Immobilizer
Prohibits fuel delivery and ignition if an attempt is
made to start the engine with an invalid ignition key.
f
f
Function to
communicate with
multiplex
communication
system
Communicates with the body ECM, A/C ECU, etc., on
the body side, to input/output necessary signals.
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—
*: Calfornia only
ENGINE — 1MZ-FE ENGINE
37
JCONSTRUCTION
The configuration of the engine control system in the new 1MZ-FE engine for RX300 is as shown in the
following chart. Shaded portions
differ from the 1MZ-FE engine for ’98 ES300.
SENSORS
MASS AIR FLOW METER
CRANKSHAFT POSITION SENSOR
ACTUATORS
VG
#10~#60
NE
(Crankshaft Angle Signal)
VVT CAM ANGLE SENOSR
Right Bank
Left Bank
ENGINE COOLANT TEMP. SENSOR
INTAKE AIR TEMP. SENSOR
THROTTLE POSITION SENSOR
(Throttle Position Signal)
IGNITION SWITCH
VV1
IGT1~6
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 KEY
AMPLIFIER
AIR FUEL RATIO SENSOR
(Right Bank & Left Bank)
EFI MAIN RELAY
No. 1 ~ No. 6 INJECTOR
ESA
IGNITION COIL with IGNITER
VV2
SPARK PLUGS
THW
THA
RSO
IAC
CONTROL VALVE
VTA1
FC
IGSW
STA
VEHICLE SPEED SENSOR
COMBINATION METER
EFI
SPD
ACMG
OXS
HTS
KNKR
KNKL
NSW
ECM
OC1
OC2
STA
PRE
CF
EVAP1
PS
STP
PTNK
TPC
W
TRC
ENG
TC
IMLD
SIL
HAFR
HAFL
TXCT
FUEL PUMP CONTROL
CIRCUIT OPENING RELAY
AIR CONDITIONING CONTROL
AIR CONDITIONING ECU
HEATED OXYGEN SENSOR HEATER
VVT-i CONTROL
VVT-i Solenoid VSV RH
VVT-i Solenoid VSV LH
EVAP CONTROL
VSV
VAPOR PRESSURE CONTROL
VSV
MALFUNCTION INDICATOR LAMP
THEFT DETERRENT INDICATOR LIGHT LAMP*2
AIR FUEL RATIO SENSOR HEATER
(Right Bank & Left Bank)
RXCK
CODE
AFR
AFL
+B
MPX2
MPX1
BATT
*: Applicable only to vehicles equipped with the TRAC System.
MULTIPLEX COMMUNICATION SYSTEM
BODY ECU
AIR CONDITIONER/METER ECU
BATTERY
ENGINE — 1MZ-FE ENGINE
38
JENGINE CONTROL SYSTEM DIAGRAM
ABS Unit
Fuel Pressure
Control
Relay
Park/Neutral Position Switch
Meter Unit
Start
Switch
Vehicle Speed Signal
Electronic Controlled
Transmission
Solenoid Valves
Fuel
Pressure
Regulator
MIL
A/C
Amplifier
Fuel Pump
DLC3
Stop Light Switch
Electric Load Switch
Battery
ECM
ORVR
Breather
Line
VSV (for EVAP
Purge Control)
Pressure
Sensor
VSV
(Pressure
Control)
Fuel
Filter
VSV (for Acoustic
Control Induction
System)
IAC Valve
Mass Air
Flow Meter
Intake Air Temp.
Sensor
Oil Control Valve
(for VVT Control)
Injector
Throttle Position
Sensor
Camshaft Position
Sensor
Oil Control Valve
EI
Camshaft
Position
Sensor
A/F Sensor
Warm-Up-TWC
ECT Sesnor
RPM Sensor
Knock
Sensor
TWC
Heated Oxygen Sensor
A/F Sensor
157EG20
Warm-Up-TWC
ENGINE — 1MZ-FE ENGINE
39
JLAYOUT OF COMPONENTS
Knock Sensor
Throttle Position Sensor
ECM
O2 Sensor
IAC Valve
Water
Temperature
Sensor
Injector
Ignition Coil
with Built-in
Ignite
Cam Position Sensor
Crank Position Sensor
A/F Sensor
Cam Position Sensor
Air Flow Meter
OCV
157EG21
ENGINE — 1MZ-FE ENGINE
40
JVVT-i CONTROL SYSTEM
General
D 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 back
by means of the cam position sensor for constant control to the target valve timing.
Throttle Position Sensor
OCV (RH bank)
Cam Position Sensor (RH bank)
OCV (LH bank)
Cam Position Sensor (LH bank)
Water Temperature Sensor
ECM
Air
Flow Meter
Crank Position Sensor
157EG22
ECM
Crank Position Sensor
Target Valve Timing
Air Flow Meter
Feedback
Throttle Position Sensor
Water Temperature Sensor
Correction
Cam Position Sensor
Actual Valve Timing
OCV
Duty Control
157EG23
ENGINE — 1MZ-FE ENGINE
41
JCONSTRUCTION AND FUNCTIONS
Construction
The camshaft on the exhaust side is driven by the timing belt from the crankshaft pulley, and the camshaft
on 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 to
torque variation. The camshaft driven gear (intake side) is integrated with the VVT-i actuator to vary the
intake camshaft valve timing.
Crankshaft Timing
Pulley
Timing Belt
Drive Gear
(scissors gear)
Exhaust Camshaft
Driven gear
Intake Camshaft
(VVT-i Actuator)
Valve timing
Varying Portion
VVT-i Actuator
Intake Camshaft
Cam Position Sensor
Exhaust Camshaft
Crankshaft
157EG22
Cam Position Sensor
Cam Position Sensor
VVT-i Actuator
157EG24
ENGINE — 1MZ-FE ENGINE
42
The ECM distributes the pressure generated by the oil pump into the advance side and retard side by means
of the OCV (oil control valve) installed on the side wall of the cylinder head for adjusting the pressures
before 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 the
intake camshaft.
The oil pressure sent from the advance or retard side path at the intake camshaft causes rotation in the
VVT-i controller vane circumferential direction to vary the intake valve timing continuously.
Vane Seal
Housing (fixed on driven gear)
Vane Portion
(fixed on intake camshaft)
Driven Gear
This illustration shows the
angle advance state.
157EG25
OCV (Oil Control Valve)
The oil control valve spool position is varied to constantly obtain the optimum valve timing according
to the duty signal sent from the ECM.
The latest timing position is set by the spring force while the engine is stopped.
VVT-i Pulley Timing
Advance Chamber
VVT-i Pulley Timing
Retard Chamber
Spool Valve
Sleeve
Drain
Spring
Connector
Drain
Oil Pressure
Coil
Plunger
157EG26
ENGINE — 1MZ-FE ENGINE
43
Operation (Hydraulic System)
The OCV selects the path to the VVT-i actuator according to the advance, retard or hold signal from the
ECM. The VVT-i actuator rotates the camshaft in the timing advance or retard position or holds it according
to the position where the fluid pressure is applied.
Operation
OCV drive signal
Advance
VVT-i Actuator
Description
Advance Signal
ECM
Duty Ratio
When the OCV is positioned
as illustrated at left by the advance signal from the ECM,
the resultant fluid pressure is
applied to the timing advance
side vane chamber to rotate
the camshaft in the timing advance direction.
Fluid Pressure
157EG27
157EG28
Delay
Rotating Direction
Vane
(fixed on intake
camshaft)
157EG35
Retard Signal
ECM
Duty Ratio
When the OCV is positioned
as illustrated at left by the retard signal from the ECM, the
resultant fluid pressure is applied to the timing retard side
vane chamber to rotate the
camshaft in the timing retard
direction.
Fluid Pressure
157EG29
157EG30
157EG36
Hold
Hold Signal
ECM
Duty Ratio
Fluid Pressure
157EG31
157EG32
157EG37
The ECM calculates the target timing angle according to
the traveling state to perform
control as described above.
After setting at the target timing, the valve timing is held
by keeping the OCV in the
neutral position unless the
traveling state changes.
This adjusts the valve timing
at the desired target position
and prevents the engine oil
from running out when it is
unnecessary.
ENGINE — 1MZ-FE ENGINE
44
ECM
In proportion to the engine speed, intake air volume, throttle position and coolant temperature, the ECM
searches an optimal valve timing under each driving condition and control the camshaft timing oil control
valve. In addition, ECM uses signal from the VVT sensors and the crankshaft position sensor to detect
the actual valve timing, thus performing feedback control to achieve the target valve timing.
" Operation During Various Driving Condition A
Full Load Perfomance
Range
4
Engine Load
Range
Range
Range
Range
Operation state
1
Range
During idling
1
At light load
2
At medium
load
3
In low to
medium speed
range with
heavy load
4
In high speed
range with
heavy load
5
Engine Speed
Valve timing
EX
EX
z
Objective
Eliminating overlap to reIN
duce blow back to the inLatest timing take side
Decreasing overlap to
!IN
eliminate blow back to the
To retard side intake side
IN
EX
To advance side
INz
EX
To advance side
IN
At low
temperatures
—
Upon starting/
stopping the
engine
—
EX
EX
3
2
151EG74
Effect
Stabilized idling rpm
Better fuel economy
Ensured engine stability
Increasing overlap to increase internal EGR for
pumping loss elimination
Better fuel economy
Improved emission control
Advancing the intake valve
close timing for volumetric
efficiency improvement
Improved torque in low
to medium speed range
!
Retarding the intake valve
close timing for volumetric
To retard side efficiency improvement
Improved output
Eliminating overlap to prevent blow back to the intake side for reduction of
IN
fuel increase at low temperatures, and stabilizing the
Latest timing idling rpm for decreasing
fast idle rotation
Stabilized fast idle rpm
Better fuel economy
Eliminating overlap to
eliminate blow back to the
Latest timing
intake side
Improved startability
IN
EX
5
ENGINE — 1MZ-FE ENGINE
45
JSFI (Sequential Multipot Fuel Injection) SYSTEM
D The L-type SFI system is adopted to adjust fuel injection volume by directly measuring the intake air
flow with a hot-wire type air flow meter.
D An air assist type fuel injection system is adopted to improve emission control and fuel economy be
facilitating fuel atomization.
Air-Fuel Ratio and Feedback Control
As illustrated below, the conventional oxygen sensor is characterized by a sudden change in its output
voltage at the threshold of the stoichiometric air-fuel ratio (14.7 to 1). In contrast, the air-fuel ratio sensor
output a voltage that is approximately proportionate to the existing air-fuel ratio by converting the oxygen
density to the voltage. As a result, the detection precision of the air-fuel ratio has been improved.
Air-Fuel Ratio Sensor
3.3V
ECM
AF−
(V)
1
Oxygen Sensor
2.2
3.0V
0.1
11
151EG30
Oxygen Sensor
Output
Air-Fuel
Ratio Sensor
(V)
4.2
Air-Fuel Ratio Sensor
Output
AF+
14.7
Air-Fuel Ratio
19
Output Characteristics
151EG31
The precision of the air-fuel feedback control has been improved through the adoption of the air-fuel ratio
sensor. As illustrated below, if the existing air-fuel ratio diverts from the stoichiometric air-fuel ratio, the
conventional oxygen sensor used to correct the air-fuel ratio at a constant proportion. However, with the
air-fuel ratio sensor, the ECM can determine the extent of diversion from the stoichiometric air-fuel ratio
and execute an immediate correction.
Rich
"
Stoichiometric
Air-Fuel Ratio
#
Lean
Injection
Volume
Previous
(Oxygen Sensor)
New
(Air Fuel
Ratio Sensor)
Disorder
New
Previous
Correction at a
Constant Proportion
Immediate Correction
151EG32
ENGINE — 1MZ-FE ENGINE
46
JACIS (ACOUSTIC CONTROL INDUCTION SYSTEM) CONTROL
General
The ECM intake control valve is opened/closed according to the engine rpm and throttle valve opening
to vary the intake manifold length in three stages for improving the torque under heavy load in the medium
speed 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 with
heavy load)
2 Engine speed between 2,700 and 3,700 rpm and throttle valve opening at 30 degrees or more (Medium
speed range with heavy load)
3 Engine speed up to 3,700 rpm with throttle valve opening at 30 degrees or less, and full range with
engine speed above 3,700 rpm (Idling range, light load range and high speed range)
Throttle Valve Opening
2700r/min 3700r/min
2
1
3
30°
3
3
Engine rpm
157EG33
157EG10
1
Low speed range with heavy load
157EG11
2
Medium speed range with heavy load
157EG12
3
Idling range, light load range and high speed range