EC01H–05

–EMISSION CONTROL EMISSION CONTROL SYSTEMEC–1

842Author: Date:

1997 LEXUS ES300 (RM511U)

EMISSION CONTROL SYSTEMPURPOSEThe emission control systems are installed to reduce the amount of CO, HC and NOx exhausted from theengine ((3) and (4)), to prevent the atmospheric release of blow–by gas–containing HC (1) and evaporatedfuel containing HC being released from the fuel tank (2).The function of each system is shown in these table.

System Abbreviation Function

(1) Positive Crankcase Ventilation

(2) Evaporative Emission Control

(3) Exhaust Gas Recirculation

(4) Three–Way Catalytic Converter

(5) Sequential Multiport Fuel injection*

PCV

EVAP

EGR

TWC

SFI

Reduces HC

Reduces evaporated HC

Reduces NOx

Reduces HC, CO and NOx

Injects a precisely timed, optimum amount of fuel for reduced

exhaust emissions

Remark: * For inspection and repair of the SFI system, refer to the SF section of this manual.

EC

01I–01

S04747

VSV for VaporPressure Sensor

Vapor PressureSensor

EGR Valve

VSV for EVAP

Vacuum Surge Tank

VSV for EGR

VSV

Charcoal Canister

EC

–2–

EM

ISS

ION

CO

NT

RO

LP

AR

TS

LAY

OU

T AN

D S

CH

EM

AT

IC D

RA

WIN

G

843Author:

Date:

1997 LEX

US

ES

300 (RM

511U)

PAR

TS

LAYO

UT

AN

D S

CH

EM

ATIC

DR

AW

ING

LOC

ATIO

N

EC01J–05

S04775

VSV for Vapor Pressure Sensor

VSV for EGR

Vacuum SurgeTank

EGR ValvePosition Sensor

EGR Valve

VCV

VSV for EVAP

CharcoalCanister

Vapor PressureSensor

Fuel Tank

To Air Cleaner

TWC

Heated OxygenSensor(Bank 1 Sensor 2)

Heated Oxygen Sensor(Bank 1 Sensor 1)

Heated Oxygen Sensor(Bank 2 Sensor 1)

–EMISSION CONTROL PARTS LAYOUT AND SCHEMATIC DRAWINGEC–3

844Author: Date:

1997 LEXUS ES300 (RM511U)

DRAWING

S05053

PCV Valve

EC01K–01

P02006

Clean Hose

Cylinder Head Side

P02477

Intake ManifoldSide

P12931

EC–4 –EMISSION CONTROL POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM

845Author: Date:

1997 LEXUS ES300 (RM511U)

POSITIVE CRANKCASEVENTILATION (PCV) SYSTEMINSPECTION1. REMOVE PCV VALVE(a) Disconnect the PCV hose from the PCV valve.(b) Remove the PCV valve.

2. INSTALL CLEAN HOSE TO PCV VALVE3. INSPECT PCV VALVE OPERATION(a) Blow air into the cylinder head side, and check that air

passes through easily.CAUTION:Do not suck air through the valve.Petroleum substances inside the valve are harmful.

(b) Blow air into the intake manifold side, and check that airpasses through with difficulty.

If operation is not as specified, replace the PCV valve.4. REMOVE CLEAN HOSE FROM PCV VALVE5. REINSTALL PCV VALVE

6. VISUALLY INSPECT HOSES, CONNECTIONS ANDGASKETS

Check for cracks, leaks or damage.

P25178

EC01L–01

EC3069

Gasket

Check Valve

S05162

S05363

Port E Port D

Port A

Port B

CompressedAir

S05360

Port C

Port D

Port A

Port B

CompressedAir

–EMISSION CONTROL EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEMEC–5

846Author: Date:

1997 LEXUS ES300 (RM511U)

EVAPORATIVE EMISSION (EVAP)CONTROL SYSTEMINSPECTION1. VISUALLY INSPECT LINES AND CONNECTIONSLook for loose connections, sharp bends or damage.2. VISUALLY INSPECT FUEL TANKLook for deformation, cracks or fuel leakage.

3. VISUALLY INSPECT FUEL TANK CAPCheck if the cap and/or gasket are deformed or damaged.If necessary, repair or replace the cap.

4. REMOVE CHARCOAL CANISTER5. VISUALLY INSPECT CHARCOAL CANISTERLook for cracks or damage.

6. CHECK FOR CLOGGED FILTER, AND STUCKCHECK VALVE AND DIAPHRAGM

(a) Install the plug to port E.(b) While holding port B closed, blow air (1.76 kPa, 18 gf/cm2,

0.26 psi) into port A and check that air flows from port D.

(c) While holding port B and port D closed, blow air (1.76 kPa,18 gf/cm2, 0.26 psi) into port A and check that air does notflow from port C.

S05361

Port C

Port B

S05362

Port C

Port B

Port A

EC–6–EMISSION CONTROL EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM

847Author: Date:

1997 LEXUS ES300 (RM511U)

(d) Apply vacuum (3.43 kPa, 25.7 mmHg, 1.01 in.Hg) to portB, check that the vacuum does not decrease when portC is closed, and check that the vacuum decreases whenport C is released.

(e) While holding port C closed, apply vacuum (3.43 kPa,25.7 mmHg, 1.01 in.Hg) to port A and check that air flowsinto port B.

If a problem is found, replace the charcoal canister.(f) Remove the plug.7. REMOVE VSV FOR EVAP8. INSPECT VSV FOR EVAP

(See page SF–52)9. REINSTALL VSV FOR EVAP10. REMOVE VSV FOR VAPOR PRESSURE SENSOR11. INSPECT VSV FOR VAPOR PRESSURE SENSOR

(See page SF–56)12. REINSTALL VSV FOR VAPOR PRESSURE SENSOR13. INSPECT VAPOR PRESSURE SENSOR

(See page SF–58)14. REINSTALL CHARCOAL CANISTER

EC01M–02

S05477

Disconnect

Ohmmeter

E2 VC

S05457

E2(–)VC(+)

S05458

Disconnect

E2(–)EGLS(+)

–EMISSION CONTROL EXHAUST GAS RECIRCULATION (EGR) SYSTEMEC–7

848Author: Date:

1997 LEXUS ES300 (RM511U)

EXHAUST GAS RECIRCULATION(EGR) SYSTEMINSPECTION1. INSPECT EGR SYSTEM

(See page DI–118)

2. INSPECT EGR VALVE POSITION SENSOR(a) Inspect the resistance of the EGR valve position sensor.

(1) Disconnect the EGR valve position sensor connec-tor.

(2) Using an ohmmeter, measure the resistance be-tween the terminals VC and E2.

Resistance: 1.5 – 4.3 k ΩIf the resistance is not as specified, replace the EGR valve posi-tion sensor.

(3) Reconnect the EGR valve position sensor connec-tor.

(b) Inspect the power output voltage of the EGR valve posi-tion sensor.(1) Disconnect the vacuum hose from the EGR valve.(2) Turn the ignition switch ON.(3) Connect a voltmeter to terminals VC and E2 of the

ECU, and measure the power source voltage.Voltage: 4.5 – 5.5 V(4) Connect a voltmeter to terminals EGLS and E2 of

the ECU, and measure the power outlet voltage un-der the following conditions: Using the MITYVAC (Hand–Held Vacuum

Pump), apply a vacuum (17.3 kPa, 130mmHg, 5.1 in.Hg) to the EGR valve.

Voltage: 3.2 – 5.1 V Release the vacuum from the EGR valve.

Voltage: 0.4 – 1.6 VIf the voltage is not as specified, replace the EGR valve positionsensor.

(5) Reconnect the vacuum hose to the EGR valve.3. REMOVE EGR POSITION SENSORRemove the 3 nuts and EGR valve position sensor from theEGR valve.

Torque: 2 N·m (20 kgf·cm, 17 in.·lbf)4. REINSTALL EGR POSITION SENSOR

Installation is the reverse order of removal.

S05452

S05455

(1)

(2)

(3)

S05454

S05478

Z Port

S Port

S05476

(kPa, mmHg, in.Hg)

Vac

uum

(3 Times)10 sec. Time

Pumping

EC–8–EMISSION CONTROL EXHAUST GAS RECIRCULATION (EGR) SYSTEM

849Author: Date:

1997 LEXUS ES300 (RM511U)

5. REMOVE EGR VALVE(a) Remove the EGR pipe.

Remove the 4 nuts, EGR pipe and 2 gaskets.HINT:Install 2 new gaskets.

Torque: 12 N·m (120 kgf·cm, 9 ft·lbf)(b) Disconnect the EGR gas temperature sensor connector

and clamp.

(c) Remove the EGR valve.(1) Disconnect these hoses and connector:

EVAP hose from EGR valve hook Vacuum hose from EGR valve EGR valve position sensor connector

(2) Remove the 3 nuts, EGR valve and gasket.HINT:Install a new gasket.

Torque:12 N·m (120 kgf·cm, 9 ft·lbf)(d) Remove the EGR gas temperature sensor.

Torque: 20 N·m (200 kgf·cm, 14 ft·lbf)6. INSPECT EGR VALVECheck for sticking and heavy carbon deposits.If a problem is found, replace the EGR valve.7. REINSTALL EGR VALVE

Installation is the reverse order of removal.

8. REMOVE VCV9. INSPECT VCV(a) Connect the MITYVAC (Hand–Held Vacuum Pump) to

port S of the VCV.(b) Plug port Z completely with fingers.

(c) Perform pumping 3 times and apply vacuum as shown inthe illustration.

(d) Stop the performing pumping and check the indicated val-ue of the MITYVAC after about 10 seconds.Standard value:15 – 24 kPa (112 – 180 mmHg, 4.4 – 7.1 in.Hg)

If the indicated value is not as specified, replace the VCV.10. REINSTALL VCV11. INSPECT VSV FOR EGR

(See page SF–50)

EC01P–01

–EMISSION CONTROL THREE–WAY CATALYTIC CONVERTER (TWC) SYSTEM

EC–9

850Author: Date:

1997 LEXUS ES300 (RM511U)

THREE–WAY CATALYTIC CONVERTER (TWC) SYSTEMINSPECTION1. CHECK TWC FOR DENTS OR DAMAGEIf any part of the protector is damaged or dented to the extent that it contacts the three–way catalytic convert-er, repair or replace it.2. CHECK EXHAUST PIPE CONNECTIONS FOR

LOOSENESS OR DAMAGE3. CHECK EXHAUST PIPE CLAMPS FOR WEAKNESS, CRACKS OR DAMAGE4. CHECK HEAT INSULATOR FOR DAMAGE5. CHECK FOR ADEQUATE CLEARANCE BETWEEN CATALYTIC CONVERTER AND HEAT

INSULATOR

EC01P–01

–EMISSION CONTROL THREE–WAY CATALYTIC CONVERTER (TWC) SYSTEM

EC–9

850Author: Date:

1997 LEXUS ES300 (RM511U)

THREE–WAY CATALYTIC CONVERTER (TWC) SYSTEMINSPECTION1. CHECK TWC FOR DENTS OR DAMAGEIf any part of the protector is damaged or dented to the extent that it contacts the three–way catalytic convert-er, repair or replace it.2. CHECK EXHAUST PIPE CONNECTIONS FOR

LOOSENESS OR DAMAGE3. CHECK EXHAUST PIPE CLAMPS FOR WEAKNESS, CRACKS OR DAMAGE4. CHECK HEAT INSULATOR FOR DAMAGE5. CHECK FOR ADEQUATE CLEARANCE BETWEEN CATALYTIC CONVERTER AND HEAT

INSULATOR

EC01Q–01

S05048

EC–10 –EMISSION CONTROL THREE–WAY CATALYTIC CONVERTER (TWC) SYSTEM

851Author: Date:

1997 LEXUS ES300 (RM511U)

REPLACEMENT1. REMOVE CONVERTER(a) Jack up the vehicle.(b) Check that the converter is cool.(c) Remove the 2 bolts and exhaust pipe stay.

Torque: 33 N·m (330 kgf·cm, 24 ft·lbf)(d) Remove the 2 bolts, and disconnect the bracket.

Torque: 33 N·m (330 kgf·cm, 24 ft·lbf)(e) Remove the 2 bolts and 2 nuts holding the front exhaust

pipe to the center exhaust pipe.Torque: 56 N·m (570 kgf·cm, 41 ft·lbf)

(f) Remove the 4 nuts holding the front exhaust pipe to theexhaust manifolds.Torque: 62 N·m (630 kgf·cm, 46 ft·lbf)

(g) Remove the front exhaust pipe (converter) and 3 gaskets.HINT:At the time of installation, please refer to the following items.Install 3 new gaskets.2. INSTALL CONVERTER

Installation is the reverse order of removal.