3UZ-FE VVt-i 4.3L V8

3UZ-FE VVt-i

 

Coming Soon

 

3UZ-FE ENGINE
DESCRIPTION
On ’01 LS430, base on the 1UZ-FE engine adopted on ’00 LS400, 3UZ-FE engine of V8, 4.3-liter, 32-valve
DOHC with the enlarged bore has been adopted.
This engine has adopted the VVT-i (Variable Valve Timing-intelligent) system, ACIS (Acoustic Control Induction
System) and ETCS-i (Electronic Throttle Control System-intelligent), and these control functions
have been optimized in order to realize the further improvement of the engine performance, fuel economy
and to reduce exhaust emissions.

 

Engine Type 3UZ-FE 1UZ-FE
No. of Cyls. & Arrangement 8-Cylinder, V Type 
Valve Mechanism 32-Valve DOHC,
Belt & Gear Drive 
Combustion Chamber Pentroof Type 
Manifolds Cross-Flow 
Fuel System SFI 
Displacement cm3 (cu. in.) 4293 (261.9) 3969 (242.1)
Bore × Stroke mm (in.) 91.0 × 82.5 (3.58 × 3.25) 87.5 × 82.5 (3.44 × 3.25)
Compression Ratio 10.5 : 1 
Max. Output [SAE-NET] 216 kW @ 5600 rpm
(290 HP @ 5600 rpm)
216 kW @ 6000 rpm
(290 HP @ 6000 rpm)
Max. Torque [SAE-NET] 434 NVm @ 3400 rpm
(320 ftVlbf @ 3400 rpm)
407 NVm @ 4000 rpm
(300 ftVlbf @ 4000 rpm)
Intake
Open –14° ~ 31° BTDC –14° ~ 36° BTDC
Valve Timing
Close 64° ~ 19° ABDC 64° ~ 14° ABDC
Exhaust
Open 46° BBDC 
Close 3° ATDC 
Fuel Octane Number RON 95 or more 
Oil Grade API SJ, EC or ILSAC 

 

MAJOR DIFFERENCES 35
The major differences between the new 3UZ-FE engine on the ’01 LS430 and the 1UZ-FE engine on the
’00 LS400 are the following:
System Features
Engine Proper
• The water passage outside of the cylinder head bolts has been changed
to improve the flow of the water around the valve seats, thus reducing
the temperature of the combustion chamber.
• The cylinder bore has been increased in size, and the thickness of the
liner has been decreased.
• The shape of the cylinder head gasket has been changed in conjunction
with the increase in the size of the cylinder bore.
• The material strength of the cylinder head bolts has been changed to
increase their axial tension. As a result, the head gaskets tightening
has been improved.
• The piston diameter has been increased in size, and its shape has been
optimized to achieve weight reduction.
• The material of the inner surface of the bushing in the small end of the
connecting rod has been changed from lead bronze alloy to phosphor
bronze alloy.
• The material of the sliding surface of the crankshaft bearing has been
changed from kelmet to aluminum alloy.
Cooling System
• An electric cooling fan system has been adopted.
• The shape of the water inlet housing has been optimized to increase
the water flow and to achieve weight reduction.
Intake and Exhaust System
• A resonator and a tuning hole have been provided in the air cleaner
inlet to reduce the amount of intake air sound.
• The air cleaner case has been increased in size to reduce the amount
of intake air sound, and the construction of the air cleaner element has
been optimized to achieve weight reduction.
• A stainless steel exhaust manifold with a single-pipe construction has
been adopted. As a result, the warm-up performance of the TWC
(Three-way Catalytic Converter) has been improved.
• Two TWCs (Three-way Catalytic Converters) have been provided in
the front, and one in the center.
• Ultra thin-wall, high-cell ceramic type TWCs have been adopted.
• A link-less type throttle body has been adopted.
Fuel System
• A saddle-shaped fuel tank has been adopted.
• A compact fuel pump in which a fuel filter, pressure regulator and jet
pump are integrated in the module fuel pump assembly has been
adopted.
• The charcoal canister has been relocated.Ignition System The construction of the ignition coil has been optimized to achieve a
compact and lightweight configuration.
36
Engine Control System
• Torque activated power train control has been newly adopted for the
control of ETCS-i. Also, the fail-safe control has been reconsidered
with the adoption of the link-less type throttle body.
• The ECM steplessly controls the speeds of the two fans along with the
adoption of an electric cooling fan system.
• A fuel cut control is adopted to stop the fuel pump when the airbag is
deployed at the front or side collision.
• A DTC (Diagnostic Trouble Code) has been newly adopted for indicating
a thermostat malfunction.
Others The ECM has been installed in the engine compartment for improved
serviceability.

 

1. Cylinder Head
 The cylinder head is made of aluminum and has intake and exhaust ports in a cross-flow arrangement.
The intake ports are on the inside and the exhaust ports on the outside of the left and right banks respectively.
 The pitch of the intake and exhaust camshafts is shortened and the valve angle is narrowed to 21° 33’.
 The left and right banks of cylinder heads are common in configuration.

NOTICE
When the cylinder heads are disassembled for servicing, be sure to assemble each cylinder head
to the correct right or left bank. The camshaft may seize if they are assembled incorrectly.

 

2. Cylinder Head Gasket
The same type of (4-layer) steel laminate cylinder head gasket used in the 1UZ-FE engine on the ’00 LS400
is used in the 3UZ-FE engine on the ’01 LS430, except that its shape has been slightly changed in accordance
with the increased cylinder displacement of the new engine.

 

3. Cylinder Block
 The cylinder block has a bank angle of 90°, a bank offset of 21 mm (0.827 in.) and a bore pitch of 105.5
mm (4.15 in.), resulting in a compact block in its length and width even for its displacement.
 Light weight aluminum alloy is used for the cylinder block.
 In contrast to the 1UZ-FE engine on the ’00 LS400, the liner thickness in the 3UZ-FE engine on the ’01
LS430 has been changed from 2 mm (0.08 in.) to 1.5 mm (0.06 in.) to achieve weight reduction and improved
cooling performance. It is not possible to bore this liner due to its thinness. The thickness of the
wall has been changed from 5.5 mm (0.22 in.) to 6.5 mm (0.26 in.), and the shape of the water passage
between the bores has been optimized to improve both cooling performance and rigidity.

 

4. Piston
 The piston head portion has adopted a taper squish shape to improve the fuel combustion efficiency.
 The sliding surface of the piston skirt has been coated with resin to reduce the amount of friction loss.
 Full floating type piston pins are used.
 By increasing the machining precision of the cylinder bore diameter, the outer diameter of the piston has
been made into one type.
 In contrast to the 1UZ-FE engine on the ’00 LS400, the placement position of the piston rings has been
slightly raised in the 3UZ-FE engine on the ’01 LS430 in order to reduce the area in which unburned
fuel is likely to accumulate during the combustion process. Furthermore, the squish area in the thrust
direction of the piston head has been discontinued and the combustion chamber has been made shallower
in order to further improve the combustion efficiency, thus improving fuel economy.

 

5. Connecting Rod 41
 The sintered and forged connecting rod is highly
rigid and has little weight fluctuation.
 A weight-adjusting boss is provided at the big end
to reduce fluctuation of weight and balance the engine
assembly.
 In contrast to the 1UZ-FE engine on the ’00 LS400,
the material of the inner surface of the bushing in
the small end of the connecting rod in the 3UZ-FE
engine on the ’01 LS430 has been changed from
lead bronze alloy to phosphor bronze alloy to reduce
the lead quantity and to further improve the wear
resistance.
 The connecting rod cap is held by plastic region
tightening bolts.
NOTE: When reusing the connecting rod cap bolts,
if the diameter at the thread is less than 7.0
mm (0.275 in.), it is necessary to replace them
with new ones.
 The connecting rods for the right and left banks are
placed in opposite directions with the outer marks
facing the crankshaft.

 

6. Crankshaft and Crankshaft Bearings
 A forged crankshaft with five main journals, four connecting rod pins and eight balance weights is used.
 Connecting rod pins and journals are induction-hardened to ensure an added reliability.

 In contrast to the 1UZ-FE engine on the ’00 LS400, the material of the sliding surface of the crankshaft
bearing in the 3UZ-FE engine on the ’01 LS430 has been changed from kelmet to aluminum alloy to
discontinue the use of lead and to further enhance the engine’s quiet operation.

 Crankshaft bearings are selected carefully according to the measured diameters of the crank journal and
cylinder block journal holes.
NOTE: The diameter of the crank journal and the cylinder block journal hole is indicated at the places shown
below.

 

VALVE MECHANISM
1. General
 Each cylinder has 2 intake valves and 2 exhaust valves. Intake and exhaust efficiency has been increased
due to the larger total port areas.
 The valves are directly opened and closed by 4 camshafts.
 The intake camshafts are driven by a timing belt, while the exhaust camshafts are driven through gears
on the intake camshafts.
 The VVT-i (Variable Valve Timing-intelligent) system is used to improve fuel economy, engine performance
and reduce exhaust emissions. For details, see page 69.
 In contrast to the 1UZ-FE engine on the ’00 LS400, an automatic timing belt tensioner with optimized
construction and body material that has been changed to aluminum has been adopted in the 3UZ-FE engine
on the ’01 LS430.

 

2. Camshaft 45
 The exhaust camshafts are driven by gears on the intake camshafts. The scissors gear mechanism has
been used on the exhaust camshaft to control backlash and reduce gear noise.
 A VVT-i controllers have been installed on the front of the intake camshafts to vary the timing of the
intake valves.
 In conjunction with the adoption of the VVT-i system, an oil passage is provided in the intake camshaft
in order to supply engine oil to the VVT-i system.
 The intake camshaft is provided with timing rotor to trigger the VVT sensor.

 

463. Intake and Exhaust Valve and Valve Lifter
 An inner shim type valve adjusting shim has been adopted as well as the 1UZ-FE engine on the ’00 LS400.
 The valve lifter, which has been made lighter and thinner.
 High-strength, heat-resistant steel is used in both the intake and exhaust valves, and soft nitriding treatment
has been applied to the stem and the face areas of the valves.
 Carbon steel with a round-shaped cross section has been adopted for the valve spring, which is used for
both the intake and exhaust valves.

 

4. Timing Pulleys, Automatic Tensioner and Timing Belt Cover
 In contrast to the 1UZ-FE engine on the ’00 LS400, an automatic timing belt tensioner with optimized
construction and body material that has been changed to aluminum has been adopted in the 3UZ-FE engine
on the ’01 LS430.
 The timing belt cover No. 3 is made of aluminum to reduce noise.
 The timing belt cover No. 1 and No. 2 are composite formed with a gasket to improve serviceability.

 

LUBRICATION SYSTEM 47
 The lubrication circuit is fully pressurized and oil passes through an oil filter.
 The trochoid gear type oil pump is directly driven by the crankshaft.
 Along with the adoption of the VVT-i (Variable Valve Timing-intelligent), right bank and left bank cylinder
heads are provided with VVT-i controllers and camshaft timing oil control valves. This system is operated
by the engine oil.

 

COOLING SYSTEM 49
1. General
 The cooling system is a pressurized, forced-circulation type.
 A thermostat, having a by-pass valve, is located on the water pump inlet side of the cooling circuit. As
the coolant temperature rises, the thermostat opens and the by-pass valve closes, so the system maintains
suitable temperature distribution in the cylinder head.
 In contrast to the 1UZ-FE engine on the ’00 LS400, the shape of the water inlet housing has been optimized
in the 3UZ-FE engine on the ’01 LS430 to achieve the smooth flow of the engine coolant.
 In contrast to the 1UZ-FE engine on the ’00 LS400, in which a fluid coupling type cooling fan was used,
the 3UZ-FE engine on the ’01 LS430 has adopted an electric cooling fan system.
 The ECM is installed in the ECM box in the engine compartment. As a result, the wiring harness has
been shortened, thus realizing weight reduction.

 

2. Water Pump
 The water pump has two volute chambers, and circulates
coolant uniformly to the left and right banks
of the cylinder block.
 The water pump is driven by the back of the timing
belt.
 The rotor is made of resin.

 

3. Water Inlet Housing
In contrast to the 1UZ-FE engine on the ’00 LS400, the shape of the water inlet housing has been optimized
in the 3UZ-FE engine on the ’01 LS430 to achieve the smooth flow of the engine coolant.

 

524. Cooling Fan System
 This system consists of 2 fans with a different number of blades. The main fan contains 5 blades and
the sub fan contains 7 blades. These fans are actuated by the cooling fan ECU in accordance with the
signals from the ECM.
A simplified sealing type reservoir tank has been provided for the fan shroud.

 

 The ECM is installed in the ECM box in the engine
compartment. As a result, the wiring harness has
been shortened, thus realizing weight reduction.

 

INTAKE AND EXHAUST SYSTEM 53
1. Air Cleaner
 A resonator and a tuning hole have been provided in the air cleaner inlet to reduce the amount of intake
air sound.
 The air cleaner case has been increased in size to reduce the amount of intake air sound, and the construction
of the air cleaner element has been optimized to achieve weight reduction.

 

2. Intake Manifold
 The low-to mid-speed range torque has been improved by increasing the length of the intake manifold
port.
 The air intake chamber consists of upper and lower sections and contains an intake air control valve. This
valve is activated by ACIS (Acoustic Control Induction System) and is used to alter the intake pipe length
to improve the engine performance in all speed ranges.

 

3. Intake Manifold Gasket 55
 A heat-barrier gasket has been adopted for use between the cylinder head and the intake manifold. This
gasket, which restrains the heat transfer from the cylinder head to the intake manifold, helps restrain the
intake air temperature and improve the charging efficiency.
 The construction of the gasket consists of resin that is sandwiched between metal gaskets.

 

4. Exhaust Manifold
 The front exhaust pipe has been shortened and the warm-up performance of the TWC (Three-Way Catalytic
Converter) has been improved.
 Cooling holes have been provided in the heat insulator for cooling the exhaust manifold.

 

FUEL SYSTEM 57
1. General
 A saddle-shaped fuel tank has been adopted.
 A compact fuel pump in which a fuel filter, pressure regulator and jet pump are integrated in the module
fuel pump assembly has been adopted.
 The charcoal canister, which was provided in the luggage compartment of the ’00 LS400, has been relocated
outside, underneath the luggage compartment on the ’01 LS430.
 A fuel returnless system has been used to reduce evaporative emissions.
 An air-assist system has been adopted to improve the atomization of fuel, thus improving the performance
of the evaporative emissions.
 A compact 4-hole type fuel injector has been used.
 The ORVR (On-Board Refueling Vapor Recovery) system has been used.
2. Fuel Returnless System
 The fuel returnless system has been used to reduce evaporative emissions. With the pressure regulator
and the fuel filter-integrated fuel pump are housed inside the fuel tank, this system eliminates the return
of fuel from the engine area. This helps prevent the internal temperature of the fuel tank from rising, and
reduces evaporative emissions.
 2 pulsation dampers are used to realize a quieter operation.

 

583. Air-Assist System
This system is designed to regulate air intake (atmospheric side) using the throttle valve, and direct it to
the nozzle of the fuel injector inside the intake manifold (negative pressure side). This promotes atomization
of the fuel while reducing emissions and improving fuel economy and idle stability.

 

4. Fuel Injector
 A compact 4-hole type fuel injector has been used.
 Air introduced from the throttle body and air gallery
flows through the air chamber formed by the O-ring
and insulator under the fuel injector and then is
mixed with the fuel. This design promotes atomization
of the fuel.

 

5. Fuel Tank 59
 The fuel tank adopts a saddle shape to allow the propeller shaft to pass through its center portion. Also,
a jet pump is provided to transfer the fuel from the side of the tank without the fuel pump to the side
with the fuel pump.
 Two sender gauges, the main and sub sender gauges, are provided to improve the accuracy of the fuel
gauge.
Jet Pump
A jet pump is adopted in the fuel tank. Since the propeller shaft is located below its center bottom, the
fuel tank of the new LS430 is shaped as indicated below.
A fuel tank with such a shape tends to cause the fuel to be dispersed into both chamber A and chamber
B when the fuel level is low, stopping the fuel in chamber B from being pumped out. To prevent this from
occurring, a jet pump has been provided to transfer the fuel from chamber B to chamber A.
This is accomplished by utilizing the flow of the fuel, so that the vacuum created by the fuel, as it passes
through the venturi is used to suck the fuel out of chamber B and send it to chamber A.

 

62IGNITION SYSTEM
1. General
 A DIS (Direct Ignition System) has been adopted. The DIS improves the ignition timing accuracy, reduces
high-voltage loss, and enhances the overall reliability of the ignition system by eliminating the distributor.
The DIS in this engine is an independent ignition system which has one ignition coil (with igniter) for each
cylinder.
 Iridium-tipped spark plugs have been adopted.
 In contrast to the 1UZ-FE engine on the ’00 LS400, compact and lightweight ignition coils with an optimized
construction have been adopted in the 3UZ-FE engine on the ’01 LS430.

 

2. Spark Plug 63
Iridium-tipped spark plugs have been adopted to realize a 120,000-mile (192,000 km) maintenance-free operation.
Their center electrode is made of iridium, which excels in wear resistance. As a result, the center electrode
is made with a smaller diameter and improved the ignition performance.

 

3. Ignition Coil (with Igniter)
The DIS provides 8 ignition coils, one for each cylinder.
The spark plug caps, which provide contact to the
spark plugs, are integrated with an ignition coil. Also,
an igniter is enclosed to simplify the system. However,
in contrast to the 1UZ-FE engine on the ’00 LS400,
compact and lightweight ignition coils with an optimized
construction have been adopted in the 3UZ-FE
engine on the ’01 LS430.

 

64SERPENTINE BELT DRIVE SYSTEM
1. General
 Accessory components are driven by a serpentine
belt consisting of a single V-ribbed belt. It reduces
the overall engine length, weight and number of engine
parts.
 An automatic tensioner eliminates the need for tension
adjustment.

 

2. Automatic Tensioner
The automatic tensioner, which mainly consists of an idler pulley, an arm, a spring case, and a torsion spring,
maintains the tension of the V-ribbed belt constant through the force of the torsion spring.

 

ENGINE CONTROL SYSTEM 65
1. General
The engine control system of the 3UZ-FE engine on the ’01 LS430 is basically same in construction and
operation as that of the 1UZ-FE engine for the ’00 LS400.
The engine control system of the 3UZ-FE engine in the ’01 LS430 and 1UZ-FE engine in the ’00 LS400
are compared below.

System Outline 3UZ-FE 1UZ-FE
SFI
Sequential
Multiport Fuel
Injection
An L-type SFI system directly detects the intake air mass
with a hot wire type air flow meter.  
ESA
El t i S k
Ignition timing is determined by the ECM based on signals
from various sensors. The ECM corrects ignition
timing in response to engine knocking.
 
Electronic Spark
Advance
2 knock sensors are used to improve knock detection.   The torque control correction during gear shifting has
been used to minimize the shift shock.  
VVT-i
Variable Valve
Timing-intelligent
Controls the intake camshaft to an optimal valve timing
in accordance with the engine condition. For details, see
page 69.
 
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. In addition, comprehensively
controls the ISC, snow mode control, cruise
control, VSC system and TRAC systems. For details, see
page 74.
 
Throttle Control
System-intelligent
Controls the throttle valve opening to effect adaptive laser
cruise control.*  —
y g
Torque activated power train control has been adopted.
Also, the fail-safe control has been reconsidered with the
adoption of the link-less type throttle body. For details,
see page 74.
 —
ACIS
Acoustic Control
Induction System
The intake air passages are switched according to the engine
speed and throttle valve angle to increase performance
in all speed ranges. For details, see page 80.
 The fuel pump speed is controlled by the fuel pump relay
and the fuel pump resistor.  
Fuel Pump Control The operation of the fuel pump will stop when the airbag
is deployed at the front or side collision. For details, see
page 84.
 —
Oxygen Sensor
Heater Control
Maintains the temperature of the oxygen sensor at an appropriate
level to increase accuracy of detection of the oxygen
concentration in the exhaust gas.
 
Cooling Fan
Control
An electric cooling fan system has been adopted. The ECM
steplessly controls the speed of the fans in accordance with
the engine coolant temperature, vehicle speed, engine
speed, and air conditioning operating conditions. As a result,
the cooling performance has been improved.
 —System Outline 3UZ-FE 1UZ-FE
Air Conditioning
Cut-Off Control
By controlling the air conditioning compressor ON or OFF
in accordance with the engine condition, drivability is maintained.
 
Evaporative
The ECM controls the purge flow of evaporative emissions
(HC) in the charcoal canister in accordance with engine conditions.
 
Emission Control Using 3 VSVs and a vapor pressure sensor, the ECM detects
any evaporative emission leakage occurring between the
fuel tank and the charcoal canister through the changes in the
tank pressure. For details, see page 85.
 
Engine Immobiliser Prohibits fuel delivery and ignition if an attempt is made to
start the engine with an invalid ignition key.  
Function to
communicate with
multiplex
communication
system
Communicates with the meter ECU, A/C ECU, etc., on the
body side, to input/output necessary signals.  
Diagnosis
When the ECM detects a malfunction, the ECM diagnoses
and memorizes the failed section.  
The diagnosis system includes a function that detects a malfunction
in the thermostat.  —
Fail-Safe
When the ECM detects a malfunction, the ECM stops or
controls the engine according to the data already stored in
the memory.
 

 

725. Main Components of Engine Control System
General
The following table compares the main components of the 3UZ-FE engine in the ’01 LS430 and 1UZ-FE
engine in the ’00 LS400.
Engine Type 3UZ-FE 1UZ-FE
Components Outline Quantity Outline Quantity
Mass Air Flow Meter Hot-Wire Type 1 
Crankshaft Position
Sensor (Rotor Teeth)
Pick-Up Coil Type (36-2) 1 
Camshaft Position Sensor
(Rotor Teeth)
Pick-Up Coil Type (1) 1 
VVT Sensor Pick-Up Coil Type (3) 2 
Throttle Position Sensor Linear Type 2 
Accelerator Pedal
Position Sensor
Linear Type 2 
Knock Sensor Built-In Piezoelectric Type 2 
Oxygen Sensor
(Bank 1, Sensor 1)
(Bank 2, Sensor 1)
(Bank 1, Sensor 2)
(Bank 2, Sensor 2)
With Heater Type 4 
Injector 4-Hole Type with
Air Assist
8 

 

Mass Air Flow Meter
A hot-wire type mass air flow meter has been
adopted. This 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
has been improved and the intake air resistance
has been reduced.

 

Crankshaft Position Sensor 73
The timing rotor of the crankshaft consists of 34
teeth, with 2 teeth missing. The crankshaft position
sensor outputs the crankshaft rotation signals every
10°, and the missing teeth are used to determine the
top-dead-center.

 

Camshaft Position Sensor
The camshaft position sensor is mounted on the left
bank cylinder head. To detect the camshaft position,
a protrusion that is provided on the timing pulley is
used to generate 1 pulse for every 2 revolutions of
the crankshaft.

 

VVT Sensor
A VVT sensor is mounted on the intake side of each
cylinder head. To detect the camshaft position, a timing
rotor that is provided on the intake camshaft is
used to generate 3 pulses for every 2 revolutions of
the crankshaft.

 

746. VVT-i (Variable Valve Timing-intelligent) System
General
The VVT-i system is designed to control the intake camshaft within a wide range of 45° (of crankshaft
angle) to provide a valve timing that is optimally suited to the engine condition, thus realizing improved
torque in all the speed ranges and fuel economy, and reduce exhaust emissions.

 

Construction and Operation 75
1) VVT-i Controller
The VVT-i controller comprises the outer gear that is driven by the timing belt, the inner gear that is
affixed to the camshaft and a movable piston that is placed between the outer gear and inner gear. Having
helical splines (twisted, vertical grooves) on its inner and outer periphery, the piston moves in the axial
direction to shift the phase of the outer gear and inner gear, thus causing the valve timing to change continuously.
The VVT tube drives the exhaust camshaft via the scissors gear that is installed on the back.

 

2) Camshaft Timing Oil Control Valve
The camshaft timing oil control valve controls the
spool valve position in accordance with the duty
control from the ECM thus allocating the hydraulic
pressure that is applied to the VVT-i controller to
the advance and the retard side. When the engine
is stopped, the camshaft timing oil control valve
is in the most retarded state.

 

76Operation
 The camshaft timing oil control valve selects the path to the VVT-i controller according to the advance,
retard or hold signal from the ECM. The VVT-i controller rotates the intake camshaft in the timing advance
or retard position or holds it according to the position where the oil pressure is applied.

 

 In proportion to the engine speed, intake air volume, throttle position and water temperature, the E7C7M
calculates 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 feed back control to achieve the target valve timing.

 

7. ETCS-i (Electronic Throttle Control System-intelligent) 79
General
 The ETCS-i system, which realizes excellent throttle control in all the operating ranges, has been adopted.
However, in the new 3UZ-FE engine, the accelerator cable has been discontinued, and an accelerator position
sensor has been provided on the accelerator pedal. Accordingly, the limp-mode control during the failsafe
mode has been changed.
 In the conventional throttle body, the throttle valve opening is determined invariably by the amount of the
accelerator pedal effort. In contrast, the ETCS-i uses the ECM to calculate the optimal throttle valve opening
that is appropriate for the respective driving condition and uses a throttle control motor to control the
opening.
 The ETCS-i controls the ISC (Idle Speed Control) system, the snow mode control system, the cruise control
system, the TRAC (Traction Control) system, and the VSC (Vehicle Skid Control) system. In addition
to these controls, a function to control the adaptive laser cruise control has been added to the model with
the adaptive laser cruise control.
 The torque-activated power train control has been newly adopted. This control enables the engine to generate
the necessary torque as desired by the driver, as well as to realize a smooth engine output characteristic.

 

1) Accelerator Pedal Position Sensor
The accelerator pedal position sensor is attached to the accelerator pedal. This sensor converts the accelerator
pedal depressed angles into electric signals with two differing characteristics and outputs them to the
ECM. One is the VPA signal that linearly outputs the voltage along the entire range of the accelerator
pedal depressed angle. The other is the VPA2 signal that outputs an offset voltage.

 

2) Throttle Position Sensor 81
The throttle position sensor is attached to the throttle body. This sensor converts the throttle valve opening
angles into electric signals with two differing characteristics and outputs them to the ECM. One is the
VTA signal that linearly outputs the voltage along the entire range of the throttle valve opening angle.
The other is the VTA2 signal that outputs an offset voltage.

 

3) Throttle Control Motor
A DC motor with excellent response and minimal power consumption is used for the throttle control motor.
The ECM performs the duty ratio control of the direction and the amperage of the current that flows to
the throttle control motor in order to regulate the opening angle of the throttle valve.

 

82Operation
The ECM drives the throttle control motor by determining the target throttle valve opening in accordance
with the respective operating condition.
In addition to the controls listed below, functions to effect torque-activated power train control and radar
cruise control (on models with adaptive laser cruise control) have been added.
1) Torque Activated Power Train Control  New Control
2) Nomal-mode Control, Power–mode control and Snow-mode Control
3) Idle Speed Control
4) Shift Shock Reduction Control
5) TRAC Throttle Control
6) VSC Coordination Control
7) Cruise Control
8) Adaptive Laser Cruise Control  New Control
1) Torque Activated Power Train Control
Controls the throttle to an optimal throttle valve opening that is appropriate for the driving condition such
as the amount of the accelerator pedal effort and the engine operating condition. As a result, excellent
throttle control and comfort in all operating ranges, as well as smooth startoff acceleration and elastic
acceleration have been achieved.

 

2) Normal-mode Control, Power-mode control and Snow-mode Control 83
 Controls the throttle to an optimal throttle valve opening that is appropriate for the driving condition
such as the amount of the accelerator pedal effort and the engine operating condition in order to realize
excellent throttle control and comfort in all operating ranges.
 If turning ON the POWER switch of the pattern select switch and selecting the power-mode, the throttle
valve opening angle is controlled to react more directly to operation of the accelerator pedal than the
normal mode. With this, sporty driving is realized.
 In situations in which low-m surface conditions can be anticipated, such as when driving in the snow,
the throttle valve can be controlled to help vehicle stability while driving over the slippery surface.
This is accomplished by turning on the SNOW switch of the pattern select switch, which, in response
to the amount of the accelerator pedal effort that is applied, reduces the engine output from that of
the normal driving level.

 

3) Idle Speed Control
Controls the ECM and the throttle valve in order to constantly effect ideal idle speed control.
4) Shift Shock Reduction Control
The throttle control is synchronized to the ECT (Electronically Controlled Transmission) control during
the shifting of the transmission in order to reduce the shift shock.
5) TRAC Throttle Control
As part of the TRAC system, the throttle valve is closed by a demand signal from the skid control ECU
if an excessive amount of slippage is created at a driving wheel, thus facilitating the vehicle in ensuring
stability and driving force.
6) VSC Coordination Control
In order to bring the effectiveness of the VSC system control into full play, the throttle valve opening
angle is controlled by effecting a coordination control with the skid control ECU.
7) Cruise Control
An ECM with an integrated cruise control ECU directly actuates the throttle valve to effect the operation
of the cruise control.

 

8) Adaptive Laser Cruise Control
In addition to the functions provided by the conventional cruise control, the adaptive laser cruise control
uses a laser radar sensor and a distance control ECU to determine the distance of the vehicle driven ahead,
its direction, and relative speed. Thus, the system can effect deceleration cruising control, follow-up cruising
control, cruising at a fixed speed control, and acceleration cruising control. To make these controls
possible, the ECM controls the throttle valve.
Fail-Safe
If an abnormal condition occurs with the ETCS-i system, the malfunction indicator lamp in the combination
meter illuminates to inform the driver.
The accelerator pedal position sensor comprises two sensor circuits. Therefore, if an abnormal condition
occurs in the accelerator pedal position sensor, and the ECM detects the abnormal voltage difference of
the signals between these two sensor circuits, the ECM transfers to the limp mode by limiting the accelerator
opening signal.
If an abnormal condition occurs in the throttle body system which comprises two sensor circuits, the ECM
detects the abnormal voltage difference of the signals between these two circuits and cuts off the current
to the throttle motor, causing the throttle valve to close. However, when the throttle motor is OFF, because
a return spring is provided in the throttle valve, the force of the spring keeps the throttle valve slightly
open from the fully closed state. In this state, fuel injection control and ignition timing retard control are
effected in accordance with the accelerator opening, thus enabling the vehicle to be operated within the
range of idling and limp mode.

 

8. ACIS (Acoustic Control Induction System) 85
General
The ACIS (Acoustic Control Induction System) is realized by using a bulkhead to divide the intake manifold
into 2 stages, with an intake air control valve in the bulkhead being opened and closed to vary the effective
length of the intake manifold in accordance with the engine speed and throttle valve opening angle. This
increases the power output in all ranges from low to high speed.

 

86Construction
1) Intake Air Control Valve
The intake air control valve, which is provided in
the middle of the intake manifold in the intake air
chamber, opens and closes to change the effective
length of the intake manifold in two stages.

 

2) VSV (Vacuum Switching Valve)
Controls the vacuum that is applied to the actuator by way of the signal (ACIS) that is output by the
ECM.

 

3) Vacuum Tank
Equipped with an internal check valve, the vacuum tank stores the vacuum that is applied to the actuator
in order to maintain the intake air control valve fully closed even during low-vacuum conditions.

 

Operation 87
1) When the Intake Control Valve Closes (VSV ON)
The ECM activates the VSV to match the longer pulsation cycle so that the negative pressure acts on
the diaphragm chamber of the actuator. This closes the control valve. As a result, the effective length
of the intake manifold is lengthened and the intake efficiency in the low-to-medium speed range is improved
due to the dynamic effect of the intake air, thereby increasing the power output.

 

2) When the Intake Control Valve Open (VSV OFF)
The ECM deactivates the VSV to match the shorter pulsation cycle so that atmospheric air is led into
the diaphragm chamber of the actuator and opens the control valve. When the control valve is open, the
effective length of the intake air chamber is shortened and peak intake efficiency is shifted to the high
engine speed range, thus providing greater output at high engine speeds.

 

9. Cooling Fan System 89
General
A cooling fan system has been adopted by the 3UZ-FE engine on the ’01 LS430. To achieve an optimal
fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, and air conditioning
operating conditions, the ECM calculates the proper fan speed and sends the signals to the cooling
fan ECU. Upon receiving the signals from the ECM, the cooling fan ECU actuates the fan motors.
Also, the fan speed is controlled by ECM using the stepless control.

 

90Operation
As illustrated below, the ECM determines the required fan speed by selecting the fastest fan speed from
among the following:
(A) The fan speed required by the engine coolant temperature, (B) the fan speed required by the air conditioning
refrigerant pressure, (C) the fan speed required by the engine speed, and (D) the fan speed required
by the vehicle speed.

 

10. Fuel Pump Control
A fuel cut control is adopted to stop the fuel pump when the airbag is deployed at the front or side collision.
In this system, the airbag deployment signal from the airbag sensor assembly is detected by the ECM, which
turns OFF the circuit opening relay.
After the fuel cut control has been activated, turning the ignition switch from OFF to ON cancels the fuel
cut control, thus engine can be restarted.

 

11. Evaporative Emission Control System 91
General
As in the ’00 LS400, the vacuum type has been adopted on the ’01 LS430 to detect leaks in the evaporative
emission control system. This vacuum type detects leaks by forcefully introducing the purge vacuum into
the entire system and monitoring the changes in the pressure. It consists of the following main components:
 A VSV (for canister closed valve) that closes the fresh air line from the air cleaner to the charcoal canister
has been adopted.
 A VSV (for pressure switching valve) that opens the evaporator line between the fuel tank and the charcoal
canister has been adopted.
 Function to close the purge line from the air intake chamber to the charcoal canister for this system is
added to the original functions of VSV (for EVAP).
 A vapor pressure sensor that measures the pressure in the fuel tank while checking for evaporative emission
leaks and sends signals to the ECM has been adopted.

 

92Operation
1) Purge Flow
When the engine has reached predetermined parameters (closed loop, engine coolant temp. above 74°C
(165°F), etc.), stored fuel vapors are purged from the chacoal canister whenever the purge valve is opened
by the ECM. At the appropriate time, the ECM will turn on the VSV (for EVAP).
The ECM will change the duty ratio cycle of the VSV (for EVAP) thus controlling purge flow volume.
Purge flow volume is determined by manifold pressure and the duty ratio cycle of the VSV (for EVAP).
Atmospheric pressure is allowed into the canister to ensure that purge flow is constantly maintained whenever
purge vacuum is applied to the canister.

 

2) ORVR (On-Board Refueling Vapor Recovery)
During refueling, low pressure above the diaphragm in the onboard recovery valve lifts allowing fuel
vapors into the charcoal canister. At the same time, the air drain valve opens and the charcoal absorbs
the fuel vapors.

 

3) Monitor 93
The monitor sequence begins with a cold engine start. The intake air temp. and engine coolant temp.
sensors must have approximately the same temperature reading. The ECM is constantly monitoring fuel
tank pressure. As the temperature of the fuel increases, pressure slowly rises. The ECM will purge the
charcoal canister at the appropriate time. With VSV (for pressure switching valve) closed, pressure will
continue to rise in fuel tank.

 

4) DTC P0440 (Evaporative Emission Control System Malfunction)
Initially, when the canister closed valve is closed, and the pressure switching valve and the purge valve
are opened, a vacuum is applied to the purge line from the air intake to the charcoal canister and to the
evaporator line from the charcoal canister to the fuel tank. Next, the purge valve is closed in order to
maintain a vacuum from the VSV (for EVAP) to the inside of the fuel tank. Then, any subsequent changes
in the pressure are monitored by the vapor pressure sensor in order to check for evaporative emission
leaks.
If a leak is detected, the MIL (Malfunction Indicator Lamp) illuminates to inform the driver. Also, the
DTC (Diagnostic Trouble Code) can be accessed through the use of a LEXUS hand-held tester.
For details on the DTCs, refer to the 2001 LEXUS LS430 Repair Manual (Pub. No. RM812U).

 

5) DTC P0441 (Evaporative Emission Control System Incorrect Purge Flow)
At a predetermined point, the ECM closed the canister closed valve and opens the pressure switching
valve causing a pressure drop in the entire EVAP system. The ECM continues to operate the VSV (for
EVAP) until the pressure is lowered to a specified point at which time the ECM closed the purge valve.
If the pressure did not drop, or if the drop in pressure increased beyond the specified limit, the ECM
judges the VSV (for EVAP) and related components to be faulty and the MIL illuminates to inform the
driver. Also, the DTC can be accessed through the use of a LEXUS hand-held tester.
For details on the DTCs, refer to the 2001 LEXUS LS430 Repair Manual (Pub. No. RM812U).

 

6) DTC P0446 (Evaporative Emission Control System Vent Control Malfunction) 95
a. Canister Closed Valve
This stage checks the VSV (for canister closed valve) and vent (air inlet side) operation. When the vapor
pressure rises to a specified pint, the ECM opens the canister closed valve. Pressure will increase rapidly
because of the air allowed into the system. No increase or an increase below specified rate of pressure
increase indicates a restriction on the air inlet side. If a malfunction is detected, the MIL illuminates
to inform the driver. Also, the DTC can be accessed through the use of a LEXUS hand-held tester.
For details on the DTCs, refer to the 2001 LEXUS LS430 Repair Manual (Pub. No. RM812U).

 

b. Pressure Switching Valve
The ECM closes the pressure switching Valve. This action blocks air entering the tank side of the system.
The pressure rise is no longer as great. If there was no change in pressure, the ECM will conclude the
pressure switching valve did not close. If a malfunction is detected, the MIL illuminates to inform the
driver. Also, the DTC can be accessed through the use of a LEXUS hand-held tester.
For details on the DTCs, refer to the 2001 LEXUS LS430 Repair Manual (Pub. No. RM812U).

 

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