PDF 1uz standalone,1uz wiring harness, -1uzfe Engine Wiring Diagram Dvrcizk Ebook - libreriainacipegobmx - 1uzfe
Wait Loading...


PDF :1 PDF :2 PDF :3 PDF :4 PDF :5 PDF :6 PDF :7 PDF :8 PDF :9 PDF :10


Like and share and download

1uzfe

1uzfe Engine Wiring Diagram Dvrcizk Ebook - libreriainacipegobmx

PDF How to wire up a 1uz fe By Nigel Wade f01 justanswer This+is+how+you+wire+up+a+1UZFE+Engine pdf PDF Schema Engine Control 1uzfeblog shoesonline co il schema engine control 1uzfe pdf PDF Lexus 1uzfe Engine Chouchousstaging chouchous lexus 1uzfe

Related PDF

How to wire up a 1uz-fe By Nigel Wade

[PDF] How to wire up a 1uz fe By Nigel Wade f01 justanswer This+is+how+you+wire+up+a+1UZFE+Engine pdf
PDF

Schema Engine Control 1uzfe

[PDF] Schema Engine Control 1uzfeblog shoesonline co il schema engine control 1uzfe pdf
PDF

Lexus 1uzfe Engine - Chouchous

[PDF] Lexus 1uzfe Engine Chouchousstaging chouchous lexus 1uzfe engine pdf
PDF

Auto Repair Toyota 1uzfe - Best Seller - tribeOS

[PDF] Auto Repair Toyota 1uzfe Best Seller tribeOS deployment tribeos io auto repair toyota 1uzfe pdf
PDF

Lexus 1uzfe Engine - Forum

[PDF] Lexus 1uzfe Engine Forum forum virpil lexus 1uzfe engine pdf
PDF

Auto Repair Manual Toyota 1uzfe Free

[PDF] Auto Repair Manual Toyota 1uzfe Free prueba apeseg pe auto repair manual toyota 1uzfe free download pdf
PDF

1uzfe Engine Wiring Diagram

[PDF] 1uzfe Engine Wiring Diagramw ww sproutworld 1uzfe engine wiring diagram pdf
PDF

Auto Repair Manual Toyota 1uzfe Free Download

[PDF] Auto Repair Manual Toyota 1uzfe Free Downloadswitch gears dk auto repair manual toyota 1uzfe free download pdf
PDF

Lexus 1uzfe Engine

[PDF] Lexus 1uzfe Enginesite uvamedalum lexus 1uzfe engine pdf
PDF

1uzfe Engine Wiring Diagram Dvrcizk Ebook - libreriainacipegobmx

1uzfe Engine Wiring Diagram 1uz wiring install instuctions north west toys 1uz wiring install instuctions 1uz fe conversion wiring harness, 85 95 22r e and
PDF

1X1S 海大科技日語(基礎篇)

国家高新技术展、创新与科研展参展商手册 - 高交会

PDF 2 v1 cecdn yun300 cn 清华 云计算和人工智能产业白皮书1539482997401 pdf PDF 万能蒸烤箱宴会细分市场2018(曲线)v1 cecdn yun300 cn 万能蒸烤箱宴会细分市场 2020181528184965164 pdf PDF 科技信息快递 中国气象局图书馆cmalibrary cn xxcp kjxxkd P020180606390282655656 pdf PDF 最新133R0330 海利普HMI、PLC综合型录V2018 01 holip

1Z0-027 Exam Questions and Answers

1z0 051 Answers - MSP Webinars

PDF 1Z0 027 iPass4Sure ipass4sure demo pdf 1Z0 027 pdf PDF 1Z0 027 Exam Name TeacherTubecdn media1 teachertube doc604 31834 pdf PDF 1Z0 027 Exam Name TeacherTubecdn media1 teachertube doc604 31836 pdf

1Z0-052-1.pdf

1Z0-061 - Pass4Sure

killtest 1Z0 052 pdf A 1 B 2 C 3 D 4 E 1, 2, and 4 F 1, 2, 3, and 4 Answer D 7 You have issued a SHUTDOWN ABORT command to bring down your database instance Consider the steps that will be

1Z0-060-Oracle Database 12c NF

Download Oracle 11g Upgrade Guide PDF

PDF Oracle Database 12c Oracle Rman Backup And Recoveryoracle 1z0 mclennan propertyai io oracle database 12c oracle rman backup and recoveryoracle 1z0 497 exam oracle database 12c essentials pdf PDF Database 12c Oracleloja n2midia br database 12c oracle pdf PDF Download Ocp Upgrade

1z0-060.v2015-03-01.by.EMMIE.150q

Get eBook \\ Oracle Database 12c New Features for - Ideate

PDF Actualtests 1z0 060 150q VCEplus ! vceplus 1z0 060 oracle actualtests 1z0 060 v2015 03 28 by lucile 150q pdf PDF Oracle Passit4sure 1z0 060 v2015 03 09 by Scott VCEplus !

1Z0-062_Oracle Database 12cInstallation and Administration

Oca Oracle Database 12c Installation And Administration Exam

PDF Oca Oracle Database 12c Installation And Administration Exam admin ifj oca oracle database 12c installation and administration exam guide exam 1z0 062 oracle press pdf PDF Oca Oracle Database 12c Installation And Administration Exam thelook almay oca oracle database 12c installation and

1Z0-330 Exam Training Material and Exam Dumps

oca oracle database sql certified expert exam guide exam 1z0 047

PDF Oracle 1Z0 330 Braindumps Jira – Atlassian jira atlassian secure attachment 323965 1Z0 330 pdf PDF Oracle 1Z0 330 PDF Questions | Valid Dumps 2019 Jira – Atlassian jira atlassian secure attachment 342460 1Z0 330

1Z0-434 - Oracle SOA Suite 12c Essentials.pdf

1z0 434 Oracle Soa Suite 12c Essentials Service - Book Library

PDF SOA Suite 12c Exam Study Guide PDF Oracle oracle soa suite 12c exam study guide 2398385 pdf PDF Oracle 1Z0 434 Dumps with Valid 1Z0 434 Exam Jira – Atlassian

Home back Next

Description

ENGINE — 1UZ–FE ENGINE

ENGINE 1UZ–FE ENGINE  DESCRIPTION The 1UZ–FE engine is a V–8, 4

Incorporating the state–of–the–art technology, this engine implements high–speed performance and utility at a high level providing an exciting feeling of a very smooth acceleration response to the pedal operation

With thorough analysis, design and precisely controlled manufacturing, major component parts have been improved to achieve very low vibration and noise level

The engine operation is accurately–controlled by the ECU (Electronic Control Unit) and maintains peak performance and efficiency at all times

ENGINE — 1UZ–FE ENGINE

 ENGINE SPECIFICATIONS AND PERFORMANCE CURVE Engine Item No

1UZ FE 1UZ–FE 8–Cylinder, V Type

Valve Mechanism

Combustion Chamber

Pentroof Type

Manifolds

Cross–flow

Displacement

Bore x Stroke

Compression Ratio Firing Order

Output (SAE–NET)

Torque (SAE–NET)

Fuel Octane Number (RON) Oil Grade* *

Refer to the next page for detail

ENGINE — 1UZ–FE ENGINE

*NOTE: Engine oil selection Use API (American Petroleum Institute) grade SG, Energy–Conserving II multigrade engine oil

Recommended viscosity is as follows, with SAE 5W–30 being the preferred engine oil for the 1UZ–FE engine

A label is added to the oil filler cap and some oil containers to help you select the oil you should use

The top portion of the label shows the oil quality by API designations such as SG

The center portion of the label shows the SAE viscosity grade, such as SAE 5W–30

“Energy–Conserving II” shown in the lower portion, indicates that the oil has fuel–saving capabilities

Oils marked “Energy–Conserving II” will have higher fuel–saving capabilities than oils marked “Energy–Conserving

ENGINE — 1UZ–FE ENGINE

 FEATURES OF 1UZ–FE ENGINE Features of the 1UZ–FE engine are shown in the following list: Features

Contents

 Compact DOHC, 32–valve, center–firing and high compression ratio combustion chamber implements a high combustion efficiency

High Performance

 ECU–controlled precise engine operation

 Reduced intake and exhaust losses resulting from large–diameter intake duct, air flow meter, dual exhaust system, etc

 Reduced cylinder head size by the adoption of a scissors gear mechanism

Lightweight and Compact Design  Cylinder block and oil pan made of aluminum alloy

 Compact, lightweight accessory drive system by means of serpentine, single belt and bracketless accessory installation

Low Noise and Vibration

Serviceability

 Outer shim type valve lifter

 Auto tensioners for timing belt and V–ribbed belt

High Reliability

Use of an aluminum oil pan having an integral stiffener

Aluminum engine mount brackets and liquid–filled compound engine mounts

Silent start type three–stage temperature–controlled auto–coupling fan

Rigid and accurately balanced crankshaft assembly

Auto tensioners for timing belt and V–ribbed belt

 Thin cast–iron liner press–fit in aluminum cylinder block

 Highly durable timing belt and auto tensioner

 Plastic region tightening bolts in major parts (cylinder head bolts, crankshaft bearing cap bolts, connecting rod cap bolts)

ENGINE — 1UZ–FE ENGINE

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 cylinder heads are compact even for a DOHC engine

The pitch of the intake and exhaust camshafts is shortened and the valve angle is narrowed to 2133′

 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

 Pentroof type combustion chamber with four valves is used

 The squish area guides the air–fuel mixture to the center of the combustion chamber to increase the combustion speed and thus maintain a stable engine operation

 Plastic region tightening bolts, having a good axial tension stability, are used for securing the cylinder heads to the block

When reusing the cylinder head bolts, make sure the diameter at the thread is not less than 0

It will be necessary to replace them with new ones if the diameter is less than specification

ENGINE — 1UZ–FE ENGINE

Cylinder Block  The cylinder block has a bank angle of 90, a bank offset of 0

 Lightweight aluminum alloy is used for the cylinder block

 A thin cast–iron liner is press–fit inside the cylinder to ensure an added reliability

NOTICE Never attempt to machine the cylinder because it has a thin 0

 Part of the volute chamber of the water pump and the water by–pass passage are incorporated into the cylinder block to shorten the engine length

 Installation bosses of the two knock sensors are located on the inner side of left and right banks

 The plastic region tightening bolts are used for the crankshaft bearing caps

When reusing the crankshaft bearing cap bolts, make sure the diameter at the thread is not less than 0

It will be necessary to replace them with new ones if the diameter is less than specification

 The starter is located inside the V–bank

 To install a local engine block heater, first remove the cover plate shown in the “A” view drawing below

ENGINE — 1UZ–FE ENGINE

NOTICE When fitting the crankshaft bearing cap, always tighten bearing

next in order to obtain roundness of the

ENGINE — 1UZ–FE ENGINE

Piston  Steel struts are used to control thermal expansion

 The skirt of each piston is striation finished (finely grooved) for maintaining lubrication and reducing friction loss

 The piston has a weight–adjusting boss to minimize fluctuation of weight among pistons and balance the engine assembly

 Piston pins are the full–floating type and are held in place with snap rings

Piston Ring  Each surface of the compression ring No

ENGINE — 1UZ–FE ENGINE

Connecting Rod  The sintered and forged connecting rod is very 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

 The connecting rod cap is held by plastic region tightening bolts

When reusing the connecting rod cap bolts, if the diameter at the thread is less than 0

 The connecting rods for the right and left banks are placed in opposite directions with the outer marks facing the crankshaft

ENGINE — 1UZ–FE ENGINE

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

 Crankshaft bearings are selected carefully according to the measured diameters of the crank journal and cylinder block journal holes

The diameter of the crank journal and the cylinder block journal hole is indicated at the places shown below

ENGINE — 1UZ–FE ENGINE NOTE:

Numbers of the crankshaft and pistons are shown on the right side

Crankshaft angles and engine strokes (intake, compression, combustion and exhaust) are shown in the table below

The firing order is 1–8–4–3–6–5–7–2

ENGINE — 1UZ–FE ENGINE

General  Each cylinder has two intake valves and two exhaust valves

 The valves are directly opened and closed by four camshafts

 The intake camshafts are driven by a timing belt, while the exhaust camshafts are driven through gears on the intake camshafts

 Use of outer shim type valve lifters makes it easy to adjust the valve clearance without removing the camshaft

ENGINE — 1UZ–FE ENGINE

Camshafts  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

 The camshaft journals and camshaft driven gear are lubricated by oil supplied to an oil passage in the center of the camshaft

Supply of oil from the cylinder heads to the camshafts is continuous, to prevent fluctuations in the oil pressure

 The cast iron camshafts are used

The cam nose is chill treated

 “T” type oil seals are used

NOTICE Be sure to follow the disassembly and reassembling procedures as directed in the Repair Manual to avoid possibility of damaging the cylinder head or camshaft timing gears (drive, driven and subgears)

ENGINE — 1UZ–FE ENGINE

—REFERENCE— Scissors Gear Mechanism To prevent the tooth surfaces of gears from seizing or being damaged when the gears are engaged, they are designed to have backlash

However, backlash generates noise when changes in torque occur

The scissors gear mechanism is one means of preventing this noise

The scissors gear mechanism uses a subgear with the same number of teeth as the drive gear and is attached to the gear on the driven side

Through the reaction force of the scissors spring, these two gears act to pinch the drive gear, reducing backlash to zero and eliminating gear noise

ENGINE — 1UZ–FE ENGINE

Valve Lifter and Valve Adjusting Shims  Aluminum alloy valve lifters are used

 The valve adjusting shims used are of the outer shim type and are located on top of the valve lifters

It is not necessary to remove the camshafts in order to replace the shims when the valve clearance is adjusted

(Method for replacing valve shims) Push down the valve lifter using an SST (Special Service Tool) to make a gap between the camshaft and the valve lifter

Direct compressed air from an air gun to the service hole in the valve adjusting shim to float the shim and remove it using a magnetic finger

Be sure to direct the air gun carefully so that you do not blow the shim away

Timing Pulleys and Belt

 An auto–tensioner is made up of a spring and oil damper, and maintains proper timing belt tension at all times

The auto–tensioner suppresses noise generated by the timing belt

 The timing belt has high heat resistance and durability

 The tooth profile of the timing belt is shown at the right

This design ensures a quiet operation and high–load transmission

ENGINE — 1UZ–FE ENGINE

General  The lubrication is fully pressurized and all oil passes through an oil filter

 The oil pump is a trochoid gear type and is directly driven by the crankshaft

ENGINE — 1UZ–FE ENGINE

Oil Pan  The oil pan is made up of two pieces

 The upper oil pan section is secured to the cylinder block and the torque converter housing, increasing rigidity

 The baffle plate controls the oil flow between the two oil pans when the vehicle is turning or is running along rough roads, etc

 An oil lever sensor is provided in the oil pan for efficient servicing

When the oil level falls below the specified level, the oil level sensor causes the low engine oil level warning light inside the combination meter to light up

ENGINE — 1UZ–FE ENGINE

Cooling Circuit  The cooling system is a pressurized, forced–circulation type

 A thermostat, having a bypass valve, is located on the water pump inlet side of the cooling circuit

As the coolant temperature rises, the thermostat opens and the bypass valve closes, so the system maintains suitable temperature distribution in the cylinder head

 A gauge coolant temperature sender, coolant temperature sensor, start injector time switch for the EFI (Electronic Fuel Injection) and BVSV (Bimetal Vacuum Switching Valve) for charcoal canister control are fitted to the front water joint

 The rear water joint has bypass outlet ports for heating the throttle body, cooling the EGR valve and hot water for the heater

ENGINE — 1UZ–FE ENGINE

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

Reservoir Tank  A pressurized valve is fitted to the reservoir

 A coolant level sensor is provided for efficient servicing

When the coolant level falls below the specified level, the coolant level sensor causes the low engine coolant level warning light inside the combination meter to light up

CAUTIONS 1

Never remove the cap while it is hot because the reservoir is also pressurized

Engine coolant is replenished from the reservoir

To do so, first loosen the plug at the top of the inlet housing (shown on Page 98) to bleed air out of the cooling system

Be sure that the system is filled with coolant completely

ENGINE — 1UZ–FE ENGINE

Coupling Fan  A three stage temperature–controlled auto coupling fan is used

The speed of the coupling fan changes in three stages based on the temperature of the air passing through the radiator

This keeps the fan speed low when the temperature is low, improving warm–up performance and reducing fan noise

The fan speed is high when the engine temperature is high, improving the cooling performance

Since part of the oil in the coupling fan is stored in the back storage chamber, the amount of oil in the operating chamber decreases at engine start

Oil resistance and the fan speed are reduced as a result immediately after engine start

The oil stored in the back storage chamber gradually flows into the operating chamber as the coupling fan keeps revolving

It eventually flows entirely into the operating chamber

ENGINE — 1UZ–FE ENGINE

Air Cleaner The air cleaner case and cap are made of resin and have a large filtering capacity for the large engine displacement

The air cleaner element is a low air resistance type and allows the air to pass through it very smoothly

Intake Air Resonator  A resonator is used to reduce the intake air noise

 The resonator is made of resin

The air passage and resonator chamber are formed separately

The resonator chamber is of the dual mode type and is separated by a partition

ENGINE — 1UZ–FE ENGINE

Intake Air Chamber  The EGR and ISC (Idle Speed Control) passages are attached to the intake air chamber

 The start injector is located at the center of the intake air chamber so that fuel is distributed evenly to all cylinders

Intake Manifold  Ports are crossed to increase the port length and inertia effects of the intake air

ENGINE — 1UZ–FE ENGINE

Exhaust Manifold  Both exhaust manifolds are made of stainless steel

 The exhaust manifolds are covered with heat insulators to protect the surrounding parts from exhaust heat

Exhaust Pipe  The stainless steel exhaust pipe consists of three sections

The center section is single pipe while the front and tail are dual pipes to reduce exhaust resistance

 The catalyst converters (start and main) are of the monolithic type three–way catalysts

 The main catalyst converter is newly developed and has a high performance

 Large mufflers (main and sub) effectively reduce noise and exhaust pressure from the large capacity engine

Applicable only to the California specification vehicles

Refer to page 161 for detail

ENGINE — 1UZ–FE ENGINE

 SERPENTINE BELT DRIVE SYSTEM  The serpentine belt drive system drives accessory components with 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

 The arm is pushed by the tension spring in a clockwise rotation direction always centering around “Z”

The pulley’s center of rotation is bolted to the arm

For this reason, when the belt stretches with time, the pulley center of rotation rotates to the right in an arc around “Z” with the arm

Thus the belt tension is always maintained appropriately

If it is outside the operation range, replace the belt

 When a new belt is installed, the graduations must be in the area indicated by “A” in the picture

ENGINE — 1UZ–FE ENGINE

General  Liquid–filled compound engine mounts are fitted on both sides of the engine to reduce vibration and noise at all speeds

 The aluminum engine mounting brackets reduce vibration and noise and minimize the total engine weight

Liquid–Filled Compound Engine Mount The engine mount combines rubber with liquid filled chambers

The fluid flows between upper and lower chambers through an orifice

In addition to vibrations being absorbed by the rubber mounting, low frequency vibration is absorbed by the fluid flowing through the orifice

Also, by decreasing the elasticity of the rubber, the dynamic spring constant has been reduced, providing greater noise reduction in the case of high frequency vibrations

ENGINE — 1UZ–FE ENGINE

Starter  The starter output is 2

Alternator  The IC regulated alternator has a large output of 1200 watts to produce enough electricity for the electric load

 The alternator is fitted directly (without brackets) to the cylinder block

ENGINE — 1UZ–FE ENGINE

General Engine control system uses an ECU (Electronic Control Unit) with a built–in microprocessor

Stored inside the ECU is the data for fuel injection duration, ignition timing and idling speed, etc

which are matched with the various engine conditions as well as programs for calculation

The ECU utilizes these data and signals from the various sensors in the vehicle and makes calculations with the stored programs to determine fuel injection duration, ignition timing and idling speed, etc

, and outputs control signals to the respective actuators which control operation

The engine ECU and transmission ECU are integrated into one and the ECU is called the engine and transmission ECU

The engine control system for the 1UZ–FE engine has the following functions: EFI (Electronic Fuel Injection) The ECU determines the fuel injection duration according to intake air volume, engine speed, coolant temperature and other signals and sends control signals to the fuel injectors

Also, this fuel injection duration is the basis for deciding the fuel injection timing

The fuel injection system in the 1UZ–FE engine is a four group injection system which injects fuel simultaneously into two cylinders once every two engine revolutions

ESA (Electronic Spark Advance) The ECU determines the amount of ignition advance over the initial set timing of the distributor by the intake air volume, engine speed, coolant temperature and other signal and sends control signals to the igniters

Also, based on signals from the knock sensors, the ECU controls the ignition timing at the optimum in accordance with the gasoline’s octane value

ISC (Idle Speed Control) By means of engine speed signals and coolant temperature signals, the ECU sends control signals to the ISC valve so that the actual idling speed becomes the same as the target idling speed stored in the ECU

Also, while the engine is warming up, the ECU, based on coolant temperature signals, sends controls signals to the ISC value to control engine speed to fast idle

EGR (Exhaust Gas Recirculation) CUT CONTROL The ECU sends signals to the EGR VSV to cut the EGR based on coolant temperature, engine speed, neutral start switch or intake air volume signals

This system maintains drivability at low coolant temperature, under light or heavy load conditions, or at high engine speed, etc

FUEL PRESSURE CONTROL The ECU sends signals to the pressure regulator VSV based on coolant temperature, intake air temperature, vehicle speed and engine start signals, and increases the fuel pressure

This system maintains restartability and idling stability when the engine is hot

FUEL PUMP SPEED CONTROL The ECU, based on fuel injection duration, sends control signals to the fuel pump control relay to control the fuel pump speed

That is, when the engine requires a large volume of fuel, the fuel pump turns at high speeds and when only a small volume of fuel is required, the pump turns at low speeds

ENGINE — 1UZ–FE ENGINE

OXYGEN SENSOR HEATER CONTROL Based on the intake air volume, engine start and coolant temperature signals, the ECU sends control signals to the oxygen sensor heater

This system maintains the oxygen sensor at the appropriate temperature in order to improve the detecting accuracy of oxygen concentration in the exhaust gas

AIR CONDITIONER CONTROL Based on the air conditioner switch signal from the air conditioner ECU, the ECU sends control signals to the magnetic clutch of the air conditioner compressor

This system, the magnetic clutch operation, is delayed for a predetermined period after the air conditioner switch is turned on

DIAGNOSIS The ECU is constantly monitoring signals from each sensor

If a malfunction occurs with the signals, the CHECK ENGINE lamp on the combination meter lights up and informs the driver of the malfunction

The content of the malfunction is stored in code in the ECU and when the TE1 and E1 terminals in the check connector or TDCL are connected, the ECU outputs the trouble code by flashing the CHECK ENGINE lamp

FAIL–SAFE If the ECU judges from the signals from each sensor that there is a malfunction, it continues the engine operation using its own data or it stops the engine

ENGINE — 1UZ–FE ENGINE

Construction The engine control system can be broadly divided into three groups: the ECU, the sensor and the actuators

Applicable only to California specification vehicles

Applicable only to vehicles equipped with the optional TRAC (Traction Control) system

ENGINE — 1UZ–FE ENGINE

Summary of Engine Control System The following list summarizes each system and control composing engine control system of the 1UZ–FE engine and types of the related sensors, ECU and others

ENGINE — 1UZ–FE ENGINE

Engine Control System Diagram

ENGINE — 1UZ–FE ENGINE

Arrangement of Engine Control System Components

ENGINE — 1UZ–FE ENGINE

EFI (Electronic Fuel Injection) The EFI system consists of the following three major systems: 1) Fuel System 2) Air Induction System 3) Electronic Control System Fuel System 1) General Fuel is pumped under pressure by the electric fuel pump from the fuel tank, through the fuel filter, to the injectors and the cold start injector

The pressure regulator controls the amount of fuel being returned to the fuel tank through the return pipe, thus adjusting the pressure of fuel to the injectors

The pulsation damper absorbs the minute fluctuations in fuel pressure due to injection of fuel

The injectors inject fuel into the intake port in accordance with injection duration signals from the ECU

The cold start injector injects fuel into the air intake chamber when the coolant temperature is low, improving startability in cold weather

ENGINE — 1UZ–FE ENGINE

A turbine pump, with little discharge pulsation of the fuel in the pump, is used

This pump consists of the motor portion and the pump portion, with a check valve, relief valve and filter also incorporated into the unit

Turbine Pump The turbine pump consists of the impeller, which is driven by the motor, and the casing and pump cover, which compose the pump unit

When the motor turns, the impeller turn along with it

Blades on the outer circumference of the impeller pull fuel from the inlet port to the outlet port

Fuel discharged from the outlet port passes through the motor portion and is discharged from the pump through the check valve

Relief Valve The relief valve open when the discharge side pressure reaches 71

3 lb/in

The relief valve prevents the fuel pressure from rising beyond that level

Residual Pressure Check Valve The check valve closes when the fuel pumps stops

The residual pressure check valve and pressure regulator both work to maintain residual pressure in the fuel line when the engine is stopped, thus easing restartability

If there were no residual pressure, vapor lock could occur easily at high temperatures, making it difficult to restart the engine

 The 1UZ–FE engine has a fuel pump speed control (ECU controlled) system which regulates the amount of electricity flowing to the fuel pump and thus the amount of fuel delivery according to the engine load

See page 149 for detail

ENGINE — 1UZ–FE ENGINE 3) Fuel Filter The fuel filter filters out dirt and other foreign particles from the fuel

It is installed at the high pressure side of the fuel pump

However, there is a slight variation in line pressure due to injection

The pulsation damper acts to absorb this variation by means of a diaphragm

ENGINE — 1UZ–FE ENGINE

Function

The pressure regulator regulates the fuel pressure to the injectors

Fuel injection quantity is controlled by the duration of the signal applied to the injectors, so that a constant pressure must be maintained to the injectors

However, as fuel is injected into the intake port and manifold vacuum varies, the fuel injection quantity will vary slights even if the injection signal and fuel pressure are constant

Therefore, to acquire an accurate injection quantity, the sum of the fuel pressure A and intake manifold vacuum B must be maintained at 41 lb/in

9 kg/cm2)

Operation Pressurized fuel from the delivery pipe pushes on the diaphragm, opening the valve

Part of the fuel flows back to the fuel tank through the return pipe

The amount of fuel return depends on the extent of the diaphragm spring tension and the fuel pressure varies according to the return fuel volume

Intake manifold vacuum is led to the chamber of the diaphragm spring side, weakening the diaphragm spring tension, increasing the volume of return fuel and lowering the fuel pressure

In short, when intake manifold vacuum rises (less pressure), fuel pressure falls only to the extent of the decrease in pressure, so that sum of the fuel pressure A and the intake manifold vacuum B is maintained at a constant

The valve is closed by the spring when the fuel pump stops

As a result, the check valve inside the fuel pump and the valve inside the pressure regulator maintain residual pressure inside the fuel line

 The 1UZ–FE engine has a fuel pressure control (ECU controlled) system which maintains the fuel pressure at higher levels than normal for a predetermined time when the engine is hot when started, maintaining the engine startability and the idle stability

See page 150 for detail

ENGINE — 1UZ–FE ENGINE 6) Fuel Injector Fuel is injected into the intake port of each cylinder in accordance with injection signals from the ECU

At the tip of the injector, there are two injection holes

The light and small plunger permits quick response to signals from the ECU

When a signal from the ECU is received by the solenoid coil, the plunger is pulled against spring force

Since the valve needle and plunger are a single unit, the valve needle is also pulled from its seat and fuel is injected

Fuel volume is controlled by the duration of the signal

In starting the engine when the engine coolant temperature is 71

However, starting the engine when engine coolant temperature is 140F (60C) or lower, the operation time of the cold start injector is controlled by the ECU

Thus, the cold start injector is controlled by the start injector time switch and the ECU simultaneously when the coolant temperature is below 71

6F (22C)

ENGINE — 1UZ–FE ENGINE

Air cleaned by the air cleaner enters the air intake chamber according to the throttle valve opening in the throttle body and the engine speed

An optical Karman–Vortex type air flow meter is provided between the air cleaner and the throttle body to optically detect the frequency of the Karman–Vortex that is generated when the air passes to measure the amount of air being taken into the engine

A throttle valve in the throttle body controls the air volume

The air regulated by the throttle valve enters the air intake chamber, is distributed to the intake manifold of each cylinder and enters the combustion chamber

ISC (Idle Speed Control) valve is also provided on the throttle body and directs the intake air bypassing the throttle body to the air intake chamber

The amount of air bypassing the throttle body is determined by a signal from the ECU to control the idle speed and fast idle speed accordingly

The air intake chamber prevents pulsation of the intake air to minimize the adverse affection to the air flow meter

This helps to increase accuracy of measurement of the intake air volume

It also prevents intake air interference in cylinders

ENGINE — 1UZ–FE ENGINE

Air Flow Meter

 Description An optical Karman–Vortex type air flow meter is used

This air flow meter measures the intake air volume electrically, enabling precise detection

It is made compact and lightweight

The simplified construction of the air passage also reduces air intake resistance

 Principle Karman–Vortex Street When a cylindrical object (Vortex generating body) is placed in the path of gaseous current, vortices (called Karman–Vortex) are generated in the wake of the object

If the Karman–Vortex frequency is f, the air velocity V and the diameter of the cylindrical object d, then the following equation can be made:

 Construction and Operation Using the above principle, the air flow meter is fitted with a vortex generator

As air flows past the vortex generator, vortices are generated at a frequency proportional to the velocity of the air flow

A calculation of the frequency can then determine the amount of air flow

The vortices are detected by subjecting the surface of thin metal foil (mirror) to the pressure of the vortices and optically detecting the vibrations in the mirror by means of a luminous diode and a photo transistor

The intake air volume signal (Ks) is the pulse signal

When the intake air volume is low, this signal has a low frequency

When the intake air volume is high, it has a high frequency

ENGINE — 1UZ–FE ENGINE

Throttle Body The throttle body contains the throttle valve that regulates the amount of intake air, the throttle position sensor that detects the throttle valve opening, and the dash pot that reduces the closing speed of the throttle valve

The throttle body has the following features:

 The throttle body contains a throttle valve, sufficiently large in diameter to meet the large engine displacement

 A linear type throttle position sensor is mounted on the throttle valve shaft

This sensor detects the throttle valve opening angle, converts it to a voltage and sends it to the engine and transmission ECU

(Refer to the next page for detail

 Engine coolant passes through the throttle body to maintain warmth under cold weather conditions

 When the optional TRAC (Traction Control) is fitted, a sub–throttle actuator, sub–throttle valve and sub–throttle position sensor are added to the throttle body

ENGINE — 1UZ–FE ENGINE

 Throttle Position Sensor The throttle position sensor is mounted on the throttle body

This sensor converts the throttle opening angle into a voltage and sends it to the ECU as the throttle position signal

A constant 5V is applied to the Vcc terminal from the ECU

As the contact slides along the resistor in accordance with the throttle valve opening angle, a voltage is applied to the VTA terminal in proportion to this angle

When the throttle valve is closed completely, the contact for the IDL signal connects between the IDL and E2 terminals

Another throttle position sensor for the sub–throttle valve is added to the vehicle with the optional TRAC (Traction Control)

It is the same as the main throttle position sensor in construction and operation

ENGINE — 1UZ–FE ENGINE

The ECU incorporates a built–in microprocessor

It controls injection duration precisely based on the data stored in its memory and signals from each sensor

Also, the ECU, based on this injection duration, controls the ignition timing

Further, the fuel injection system is a four group injection system

The ECU controls to inject fuel into two cylinders simultaneously once every two engine revolutions

ENGINE — 1UZ–FE ENGINE 2) Construction and Function of Relevant Sensors a

Cam Position Sensors and Engine Speed Sensor

 General Revolution of the G signal plate on the camshaft and Ne signal plate on the crankshaft alters the air gap between the projection of the plate and the G pickup coil (or the Ne pickup coil)

The change in the gap creates an electromotive force in the pickup coil

This voltage appears as an alternating output since it reverses its direction periodically as the plate approaches and leaves the pickup coil

 Cam Position Sensors (G1 and G2 signals) The G1 signal informs the ECU of the standard crankshaft angle, which is used to determine injection timing and ignition timing in relation to TDC of No

6 cylinder

G2 sensor conveys the same information for No

1 cylinder

These sensors are made up of (1) signal plate, which is fixed to the camshaft timing pulley and turn once for every two rotations of the crankshaft, and (2) the two sensors (G1 and G2 sensors), which are fitted to the distributor housing

The G1, G2 signal plates are provided with a projection which activates the G1 and G2 sensors once for each rotation of the camshaft, generating the wave forms as shown in the chart

From these signals, the ECU detects when the No

6 and No

ENGINE — 1UZ–FE ENGINE

 Engine Speed Sensor (Ne signal) The Ne signal is used by the ECU to detect the actual crankshaft angle and the engine speed

The ECU determines the basic injection duration and basic ignition advance angle by these signals

Ne signals are generated in the Ne sensor by the Ne signal plate like the G1 and G2 signals

The only difference is that the signal plate for the Ne signal has 12 teeth

Therefore, 12 Ne signals are generated per engine rotation

From these signals, the ECU detects the engine speed as well as each 30 change in the engine crankshaft angle

ENGINE — 1UZ–FE ENGINE b

Oxygen Sensors Four oxygen sensors in total are fitted, one each in front of and after the start catalyst converters

The one in front of the catalyst converter is the main oxygen sensor and after the converter is the sub–oxygen sensor

The main and sub–oxygen sensors are identical in construction and function, except for the fact that the main oxygen sensor has a heater

The O2 sensor consists of a test tube shaped zirconia element with a thin layer of platinum coated to both the inside and outside

This sensor is fitted to the exhaust manifolds and exhaust pipes on both the left and right sides to sense oxygen concentration (air–fuel ratio) in the exhaust gas

If there is a difference in the oxygen concentration on the two sides of the zirconia element, an electromotive force is generated, or if the temperature of the O2 sensor becomes high, the platinum acts as a catalyst, causing the oxygen in the exhaust gas to react with the CO

This decreases the oxygen volume in the gas

The zirconia element’s electromotive force changes suddenly at the boundary near the ideal air–fuel ratio

Using these properties, exhaust gas is passed over the outer surface of the O2 sensor and atmospheric air is introduced into the inside of the sensor

The sensor accurately detects whether the oxygen concentration, that is, the air–fuel ratio, is higher (rich) or lower (lean) than the ideal air–fuel ratio

If the air–fuel is rich, the zirconia element generates high voltage (approximately 1V)

This “rich” signal is sent to the ECU

Conversely, if the air–fuel ratio is lean, the electromotive force of the O2 sensor is low

The ECU increases or decreases the injection volume in accordance with these signals

A heater is provided in the sensors which are fitted to the exhaust manifolds

It heats the zirconia element

This heater is controlled by the ECU

When the intake air volume is low (the exhaust gas temperature is low), current flows to the heater, maintaining the sensor accuracy

ENGINE — 1UZ–FE ENGINE

Determination of Injection Timing When the ECU receives the G1 signal from the cam position sensor and then the Ne signal from the engine speed sensor in this order, it determines that the crankshaft angle at No

When the Ne signal is received immediately after the G2 signal, it judges that the crankshaft angle at No

The ECU accurately calculates the crankshaft angle based on G1, G2 and Ne signals and determines the injection timing accordingly

Principle of Fuel Injection Duration Control The fuel injection duration is determined by the basic injection duration which is determined by intake air volume and the engine speed, plus any compensation based on signals from various sensors

During engine starting (cranking), it is determined differently because the amount of intake air is not stable during cranking

Once the engine is started, the ECU determines the duration of injection in the following steps: Step 1: Determination of Basic Injection Duration The ECU selects, from the data stored in its memory, an injection duration that is suitable for the intake air volume (detected by the air flow meter) and the engine rpm (detected by the engine speed sensor)

This injection duration is called the “basic injection duration

” Step 2: Determination of Adjusted Duration of Injection Under most engine condition, the engine runs smoothly at an air–fuel mixture ratio of approximately 14

However, when the engine is still cold, or when an extra load is applied to the engine, the air–fuel ratio is reduced to below 14

The ECU detects these engine conditions by means of the water temp

sensor, throttle position sensor and intake air temp

, and corrects the basic injection duration to optimize it for the existing engine conditions

Also, even under normal engine conditions, the injection duration is corrected by the signals from the oxygen sensors to keep the air–fuel ratio within a narrow range near 14

The corrected time is called the “adjusted injection duration”

Step 3: Determination of Injection Signal Length There is a slight delay between the time the ECU sends an injection signal to the injectors and the time the injectors actually open

This delay becomes longer the more the voltage of the battery drops

The ECU compensates for this delay by lengthening the injection signal by a period corresponding to the length of the delay

This corrects the actual injection period so that it corresponds with that calculated by the ECU

ENGINE — 1UZ–FE ENGINE

Starting Injection Control During engine starting, it is difficult for the air flow meter to accurately sense the amount of air being taken in due to large fluctuations in rpm

For this reason, the ECU selects from its memory an injection duration that is suitable for the coolant temperature, regardless of intake air volume or engine rpm

It then adds to this an intake air temperature correction and a voltage correction, to obtain the injection duration

RELEVANT SIGNALS

Engine speed (Ne) Coolant temperature (THW) Intake air temperature (THA) Ignition switch (STA) Battery voltage (+B) Throttle position sensor (VTA1, VTA2)

CONDITIONS Engine speed below a predetermined level, or STA on

ENGINE — 1UZ–FE ENGINE

After–Start Injection Control

When the engine is running more or less steadily above a predetermined level rpm, the ECU determines the injection signal duration as explained below: Injection Signal Duration = Basic Injection Duration x Injection Correction Coefficient* + Voltage Correction * Injection correction coefficient is calculated by the sum and product of various correction coefficients

i) Basic Injection Duration This is the most basic injection duration, and is determines by the volume of air being taken in (Ks signal) and the engine speed (Ne signal)

The basic injection duration can be expressed as follows:

The intake air volume may vary with the air density due to fluctuation of the air temperature and atmospheric pressure

The variation of air density is corrected as follows:

 Intake Air Temperature Correction The density of the intake air will change depending upon its temperature

For this reason, the ECU must be kept accurately informed of both the intake air volume (by means of the air flow meter) and the intake air temperature (by means of the intake air temp

sensor) so that it can adjust the injection duration to maintain the air–fuel ratio currently required by the engine

For this purpose, the ECU considers 68F (20C) to be the “standard temperature” and increases or decreases the amount of fuel injected, depending upon whether intake air temperature falls below or rises above this standard

RELEVANT SIGNAL Intake air temperature (THA)

ENGINE — 1UZ–FE ENGINE

 High Altitude Compensation The density of oxygen in the atmosphere is smaller at high altitudes

If the fuel is injected under the same conditions as sea level, the amount of intake air volume measured by the air flow meter for mixture with the fuel will be insufficient and the air–fuel mixture becomes too rich

For this reason, the ECU, according to signals from the high altitude compensation sensor, adjusts signals from the air flow meter and determines the corresponding fuel injection volume

RELEVANT SIGNAL High altitude compensation (HAC)

ii) Injection Corrections The ECU is kept informed of the engine running conditions at each moment by means of signals from various sensors, and makes various corrections in the basic injection duration based on these signals

 After–Start Enrichment Immediately after starting (engine speed above a predetermined rpm), the ECU causes an extra amount of fuel to be supplied for a certain period to aid in stabilizing engine operation

The initial correction value is determined by the coolant temperature, and the amount gradually decreases thereafter at a certain constant rate

RELEVANT SIGNAL  Engine speed (Ne)

 Coolant temperature (THW) CONDITION Engine speed above a predetermined rpm

 Warm–Up Enrichment As fuel vaporization is poor when the engine is cold, if a richer fuel mixture is not supplied, the engine will run poorly

For this reason, when the coolant temperature is low, the water temp

sensor informs the ECU to increase the amount of fuel injected to compensate

As the coolant warms up, the amount of warm–up enrichment decreases, reaching zero (correction coefficient = 1

RELEVANT SIGNAL  Engine speed (Ne)

ENGINE — 1UZ–FE ENGINE

 Acceleration Enrichment During Warm–Up The ECU causes an extra fuel to be supplied during acceleration when the engine is still warming up in order to aid drivability

Through calculation of the amount of change in the intake air volume per engine revolution, the ECU detects the engine acceleration or deceleration condition

The correction value is determined according to the coolant temperature and the strength of acceleration or deceleration

The control is performed separately for each bank

RELEVANT SIGNALS  Air flow meter (Ks)

Engine speed (Ne) Coolant temperature (THW) Intake air temperature (THA) Ignition switch (STA) High altitude compensation (HAC)

CONDITIONS Intake air volume per engine revolution changes (acceleration or deceleration) with coolant temperature below 176F (80C)

However, if any of the following occurs, the ECU stops calculating this change and halts the injection of extra fuel:  Engine speed falls below a predetermined rpm

 Fuel cut–off occurs  Intake air volume becomes smaller than a certain level

 Power Enrichment When the engine is operating under heavy load conditions, the injection volume is increased in accordance with the engine load in order to ensure good engine operation

The correction value is determined according to the intake air volume or throttle valve opening angle

RELEVANT SIGNALS  Throttle position (VTA1,2)

Air flow meter (Ks) Engine speed (Ne) Coolant temperature (THW) Intake air temperature (THA) High altitude compensation (HAC)

CONDITIONS Throttle valve opening angle above 60 or intake air volume larger than a certain level

ENGINE — 1UZ–FE ENGINE

 Air–Fuel Ratio Feedback Correction The ECU corrects the ignition duration based on the signals from the main oxygen sensors to keep the air–fuel ratio within a narrow range near the ideal air–fuel ratio

(Closed look operation) Further, in order to prevent overheating of the catalyst and assure drivability under the following conditions, the air–fuel ratio feedback operation does not work: (Open loop operation)

 During engine starting  During after–start

 During traction control  Fuel cut–off occurs

 Coolant temperature below a predetermined level The ECU compares the voltage of the signals sent from the main oxygen sensors with a predetermined voltage

As a result, if the voltage of the signal is higher, the air–fuel ratio is judged to be richer than the ideal air–fuel ratio and the amount of fuel injected is reduced at a constant rate

If the voltage of the signal is lower, it is judged that the air–fuel ratio is leaner than the ideal, so the amount of fuel injected is increased

In addition, the ECU corrects the skip amount of “rich” or “lean” mixture based upon signals from the two sub–oxygen sensors

This implements a more accurate feedback correction

The control is performed separately for each bank

iii) Voltage Correction There is a slight delay between the time the ECU sends an injection signal to the injectors actually open

This delay becomes longer the more the voltage of the battery drops

This means that the length of time that the injector valves remain open would become shorter than that calculated by the ECU, causing the actual air–fuel ratio to become higher (i

, leaner) than that required by the engine, if this were not prevented by voltage correction

In voltage correction, the ECU compensates for this delay by lengthening the injection signal by a period corresponding to the length of the delay

This corrects the actual injection period so that it corresponds with that calculated by the ECU

RELEVANT SIGNALS Battery voltage (+B)

ENGINE — 1UZ–FE ENGINE

Fuel Cut–Off

 Fuel Cut–Off During Deceleration During deceleration from a high engine speed with the throttle valve completely closed, the ECU halts injection of fuel in order to improve fuel economy and emission

When the engine speed falls below a certain rpm or throttle valve is opened, fuel injection is resumed

These fuel cut–off and fuel injection resumption speeds are high when the coolant temperature is low

RELEVANT SIGNALS

 Throttle position (IDL1)  Engine speed (Ne)  Coolant temperature (THW) CONDITION IDL contacts are closed with engine speed above fuel cut–off speed

CONDITIONS FOR RESUMPTION OF FUEL INJECTION Engine speed drops below fuel injection resumption speed, or IDL contacts are open

 Fuel Cut–Off Due to High Engine Speed To prevent engine over–run, fuel injection is halted if the engine speed rises above 6500 rpm

Fuel injection is resumed when the engine speed falls below this level

Cold Start Injector Control To improve startability when the engine is cold, the injection duration of the cold start injector is controlled not only by the start injector time switch but by the ECU in accordance with the coolant temperature

Once the engine has been started, current to the cold start injector is cut off and injection is terminated

RELEVANT SIGNALS

 Coolant temperature (THW)  Ignition switch (STA, IGSW)  Engine speed (Ne) CONDITION The engine is cranking and the coolant temperature is below 140F (60C)

ENGINE — 1UZ–FE ENGINE

ESA (Electronic Spark Advance) General In order to maximize engine output efficiency, the air–fuel mixture must be ignited when the maximum combustion pressure occurs

that is, at about 10 after TDC

However, the time from ignition of the air–fuel mixture to the maximum combustion pressure varies depending on the engine speed and the intake air volume

Ignition must occur earlier when the engine speed is higher

In the conventional system, the timing is advanced by the governor advancer

When the intake air volume per engine revolution is small (high vacuum), ignition must also be advanced, and this is achieved by the vacuum advancer in the conventional system

Actually, optimum ignition timing is affected by a number of other factors, such as the shape of the combustion chamber and the temperature inside the combustion chamber, etc

, in addition to the engine speed and the intake air volume

Therefore, the governor and vacuum advance do not provide ideal ignition timing for the engine

With the ESA (Electronic Spark Advance) system, the engine is provided with nearly ideal ignition timing characteristics

The ECU determines ignition timing from its internal memory, which contains optimum ignition timing data for each engine condition, based on signals detected by various sensors, and then sends signals to the igniter

Since the ESA always ensures optimum ignition timing, both fuel efficiency and engine power output are maintained at optimum levels

Governor Advancing

Conventional

ENGINE — 1UZ–FE ENGINE

The ignition timing is determined by the ECU based on signals (G1, G2, Ne) from sensors

When it is determined, the ECU sends an IGt signal to the igniter at a predetermined timing (30 crankshaft angle) before ignition

The transistor inside the igniter is turned on by this signal and primary current is supplied from the battery via the ignition switch to the ignition coil

When the crankshaft position reaches the ignition timing, the ECU stops supplying the IGt signal

The transistor inside the igniter is turned off and the primary current to the ignition coil is cut off as a result

At this time, the secondary voltage is induced in the ignition coil

The secondary voltage is distributed and causes sparks from the spark plug

The counter–electromotive force that is generated when the primary current is shut off causes an ignition confirmation signal (IGf), which is sent to the igniter

Two igniters are used in the engine, one each for four cylinders

ENGINE — 1UZ–FE ENGINE

Construction and Function of Relevant Sensor Knock Sensor The knock sensor is provided on the left and right banks of the cylinder block

A piezoelectric ceramic element is incorporated into the sensor

If knocking develops in the engine, this piezoelectric element, by resonating with the knocking vibration, generates a voltage which corresponds with the knocking strength and sends a signal to the ECU

The ECU uses this signal to retard the ignition timing to prevent the knocking

—REFERENCE— Excessive knocking may damage the engine

However, the engine operation in a marginal knocking condition is the most advantageous to the engine output and fuel economy

ENGINE — 1UZ–FE ENGINE

Judging Crankshaft Angle In order to control the ignition timing, it is necessary for the ECU to know where compression top dead center is

In this engine, the ECU judges that the crankshaft has reached 5 BTDC of the compression cycle when it receives the first Ne signal following a G1 (or G2) signal

Therefore, the ECU calculates the ignition timing, and advances or retards the timing accordingly, using 5 BTDC as a reference point

If the ignition timing is set to 10 BTDC with terminals TE1 and E1 shorted, the crankshaft angle will be 10 BTDC at the time of the next Ne signal after the G1 (or G2) signal

This is known as the initial ignition timing

Calculating Ignition Timing The ECU selects the basic ignition advance angle from the values stored in its memory based on the intake air volume and engine speed, then adds corrections based on signals from each sensor to determine the actual ignition timing

Ignition Timing = Initial Ignition Timing + Basic Ignition Advance Angle + Corrective Ignition Advance (or Retard) Angle

Igniter Control The ECU sends an ignition timing signal (IGt1,2) to the igniter based on signals from each sensor so as to achieve the optimum ignition timing

This ignition timing signal goes on just before the ignition timing calculated in the ECU, then the ignition timing signal goes off

The spark plug fires at the point when this signal goes off

ENGINE — 1UZ–FE ENGINE

and 2) After–start ignition control, in which various corrections (made by the ECU based on signals from the relevant sensors) are added to the basic advance angle, which is determined by the intake air volume signal and the engine speed signal during normal operation

ENGINE — 1UZ–FE ENGINE

Starting Ignition Control

Since the engine speed is still below a specified rpm and unstable during and immediately after starting, the ECU cannot accurately determine the correct ignition timing

For this reason, the ignition timing is fixed at the initial ignition timing of 5 BTDC until engine operation is stabilized

RELEVANT SIGNALS

 Engine speed (Ne)  Ignition switch (STA) CONDITIONS Engine speed below specified rpm, or STA on

At engine adjustment time, etc

, with the vehicle stopped, confirm the ignition timing by connecting the TE1 and E1 terminals in the check connector or TDCL with the throttle valve fully closed

Under the above conditions, ignition advance should not be occurring and the ignition timing should be the initial ignition timing (10 BTDC)

After–Start Ignition Control i) Basic Ignition Advance Angle Control This corresponds to the vacuum advance and governor advance angles in conventional type ignition system

The memory in the ECU contains optimum advance angle data for the intake air volume and the engine speed

The ECU selects the basic ignition advance angle from memory according to the engine speed signals from the engine speed sensor and the intake air volume signals from the air flow meter

 IDL Contacts Open (OFF) When the IDL contacts open, the ECU determines the basic ignition advance angle based upon data stored in the memory

This data can be shown in the form of a table, as shown in the chart

RELEVANT SIGNALS

Basic Ignition Advance Angle Data

 Air flow meter (Ks)  Engine speed (Ne)  Throttle position (IDL1)  Intake air temperature (THA)  High altitude compensation (HAC) —REFERENCE— Since the capacity of the ECU’s memory is limited, it cannot hold all possible advance angle data

For this reason, the ECU selects the value that is the closest to the required value for each particular combination of engine speed and intake air volume

It then carries out proportional calculations to find the optimum ignition timing for the given engine speed and the intake air volume

 IDL Contacts Closed (ON) When the IDL contacts close, the ignition timing is advanced as shown, in accordance with the engine speed, whether the air conditioner is on or off, and whether neutral start switch is on or off

RELEVANT SIGNALS

 Throttle position (IDL1)  A/C switch (A/C)  Engine speed (Ne)  Neutral start switch (NSW)  Vehicle speed (SP1)

ENGINE — 1UZ–FE ENGINE ii) Corrective Ignition Advance Angle Control

 Warm–Up Correction When the coolant temperature is low, the ignition timing is advanced according to it to improve drivability

RELEVANT SIGNALS  Coolant temperature (THW)

 Intake air volume (Ks)  Engine speed (Ne)  Intake air temperature (THA)  High altitude compensation (HAC)  EGR Correction When the EGR is operating and the IDL contacts are turned off, the ignition timing is advanced according to the amount of intake air and the engine rpm to improve drivability

RELEVANT SIGNALS  Intake air volume (Ks)

 Engine speed (Ne)  Intake air temperature (THA)  Throttle position (IDL1, VTA1, VTA2)  High altitude compensation (HAC)  Coolant temperature (THW)  Neutral start switch (NSW)  Traction control (TRC)* * Models with optional TRAC system

ENGINE — 1UZ–FE ENGINE

 Knocking Correction The ignition timing at which engine knocking occurs differs according to the fuel octane value

The ECU controls the ignition timing at the optimum timing to correspond to the fuel octane value

If engine knocking occurs, the knock sensor converts the vibration from the knocking into voltage signals and sends them to the ECU

The ECU judges whether the knocking strength is at one of three levels

strong, medium or weak, according to the strength of the knock signals and changes the corrective ignition retard angle

That is, if knocking is strong, the ignition timing is retarded a lot, and if it is weak, it is retarded a little

When engine knocking stops, the ECU stops retarding the ignition timing and advances it by fixed angles a little at a time

If ignition timing advance continues and engine knocking recurs, ignition timing is again retarded

The ECU feeds back signals from the knock sensor to correct ignition timing as shown below

The knocking is judged for each cylinder at the time of ignition

But knocking correction is performed for all cylinders at one time

RELEVANT SIGNALS  Engine speed (Ne)

 Intake air volume (Ks)  Coolant temperature (THW)  Engine knocking (KNK1) (KNK2) CONDITIONS

 Intake air volume per engine revolution is larger than a certain level

 Ignition timing is not retarded at coolant temperature below 140F (60C)

ENGINE — 1UZ–FE ENGINE

 Torque Control Correction Each clutch and brake of the planetary gear unit in the transmission generates shock more or less during shifting

In the 1UZ–FE engine of the Lexus, this shock is minimized by momentarily retarding the ignition timing when gears are shifted up or down in the automatic transmission

When the ECU judges a gear shift RELEVANT SIGNALS timing according to signals from various sensors, it activates the shift  Vehicle speed (SP2) control solenoid valves to perform gear shift