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Lexus ES300 (1997 year). Manual - part 455

EM03T–03

S04507

CO/HC Meter

–

ENGINE MECHANICAL

CO/HC

EM–1

738

1997 LEXUS ES300 (RM511U)

CO/HC

INSPECTION

HINT:
This check is used only to determine whether or not the idle CO/
HC complies with regulations.
1.

INITIAL CONDITIONS

(a)

Engine at normal operating temperature

(b)

Air cleaner installed

(c)

All pipes and hoses of air induction system connected

(d)

All accessories switched OFF

(e)

All vacuum lines properly connected

HINT:
All vacuum hoses for EGR systems, etc. should be properly
connected.
(f)

SFI system wiring connectors fully plugged

(g)

Ignition timing check correctly

(h)

Transmission in neutral position

(i)

Tachometer and CO/HC meter calibrated by hand

START ENGINE

RACE ENGINE AT 2,500 RPM FOR APPROX. 180
SECONDS

INSERT CO/HC METER TESTING PROBE AT LEAST
40 cm (1.3 ft) INTO TAILPIPE DURING IDLING

IMMEDIATELY CHECK CO/HC CONCENTRATION
AT IDLE AND/OR 2,500 RPM

HINT:
When doing the 2 mode (idle and 2,500 rpm) test, these mea-
surement order prescribed by the applicable local regulations.

EM–2

–

ENGINE MECHANICAL

CO/HC

739

1997 LEXUS ES300 (RM511U)

Troubleshooting
If the CO/HC concentration does not comply with regulations,
troubleshoot in the order given below.
See the table below for possible causes, and then inspect and
correct the applicable causes if necessary.

Problems

Causes

Normal

High

Rough idle

1. Faulty ignitions:

Incorrect timing

Fouled, shorted or improperly gapped plugs

Open or crossed high–tension cords

2. Incorrect valve clearance

3. Leaky EGR valve

4. Leaky intake and exhaust valves

5. Leaky cylinders

Low

High

Rough idle

(Fluctuating HC reading)

1. Vacuum leaks:

PCV hoses

EGR valve

Intake manifold

Air intake chamber

Throttle body

IAC valve

Break booster line

2. Lean mixture causing misfire

High

Rough idle

(Black smoke from exhaust)

1. Restricted air filter

2. Plugged PCV valve

3. Faulty SFI systems:

Faulty pressure regulator

Defective ECT sensor

Faulty ECM

Faulty injectors

Faulty throttle position sensor

Faulty MAF meter

EM03U–03

P19471

Compression Gauge

–

ENGINE MECHANICAL

COMPRESSION

EM–3

740

1997 LEXUS ES300 (RM511U)

COMPRESSION

INSPECTION

HINT:
If there is lack of power, excessive oil consumption or poor fuel
economy, measure the compression pressure.
1.

WARM UP AND STOP ENGINE

Allow the engine to warm up to normal operating temperature.
2.

REMOVE IGNITION COILS AND HIGH–TENSION
CORDS (See page

IG–7

)

REMOVE SPARK PLUGS

Using a 16 mm plug wrench, remove the 6 spark plugs.
4.

CHECK CYLINDER COMPRESSION PRESSURE

(a)

Insert a compression gauge into the spark plug hole.

(b)

Fully open the throttle.

(c)

While cranking the engine, measure the compression
pressure.

HINT:
Always use a fully charged battery to obtain engine speed of
250 rpm or more.
(d)

Repeat steps (a) through (c) for each cylinder.

NOTICE:
This measurement must be done in as short a time as pos-
sible.

Compression pressure:
1,500 kPa (15.3 kgf/cm

, 218 psi)

Minimum pressure:
1,000 kPa (10.2 kgf/cm

, 145 psi)

Difference between each cylinder:
100 kPa (1.0 kgf/cm

, 15 psi) or less

(e)

If the cylinder compression in 1 or more cylinders is low,
pour a small amount of engine oil into the cylinder through
the spark plug hole and repeat steps (a) through (c) for
cylinders with low compression.

If adding oil helps the compression, it is likely that
the piston rings and/or cylinder bore are worn or
damaged.

If pressure stays low, a valve may be sticking or
seating is improper, or there may be leakage past
the gasket.

REINSTALL SPARK PLUGS

INSTALL IGNITION COILS AND HIGH–TENSION
CORDS (See page

IG–8

)