Toyota Sequoia (2005). Manual - part 648

EM–2

–

ENGINE MECHANICAL

CO/HC

2581

5.

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

HINT:
When performing the 2 mode (2,500 rpm and idle) test, follow
the measurement orders are prescribed by the applicable local
regulations.
If the CO/HC concentration does not comply with regulations,
perform troubleshooting in the order given below.
(a)

Check the air–fuel ratio sensors and heated oxygen sen-
sors operation.(See page 

DI–88

 and 

DI–93

)

(b)

See the table below for possible causes, and then inspect
and correct the applicable causes if necessary.

CO

HC

Problems

Causes

Normal

High

Rough idle

7. Faulty ignitions:

Incorrect timing

Fouled, shorted or improperly gapped plugs

8. Incorrect valve clearance

9. Leaky intake and exhaust valves

10.Leaky cylinders

Low

High

Rough idle

(fluctuating HC reading)

1. Vacuum leaks:

PCV hoses

Intake manifold

Throttle body

Brake booster line

2. Lean mixture causing misfire

High

High

Rough idle

(Black smoke from exhaust)

1. Restricted air filter

2. Faulty SFI systems:

Faulty pressure regulator

Defective ECT sensor

Faulty ECM

Faulty injectors

Faulty throttle position sensor

Faulty MAF meter

EM0KR–10

A04458

Compression
Gauge

–

ENGINE MECHANICAL

COMPRESSION

EM–3

2582

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 SPARK PLUGS

 

(See page 

IG–1

)

3.

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:
1,373 kPa (14.0 kgf/cm

2

, 199 psi) or more

Minimum pressure:
1,030 kPa (10.5 kgf/cm

2

, 149 psi)

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

2

, 14 psi) or less

(e)

If the cylinder compression in one or more cylinders is low,
pour 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, chances are
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.

4.

REINSTALL SPARK PLUGS

 

(See page 

IG–1

)

EM0KS–09

A23300

A23301

EM–4

–

ENGINE MECHANICAL

VALVE CLEARANCE

2583

VALVE CLEARANCE

INSPECTION

HINT:
Inspect and adjust the valve clearance when the engine is cold.
1.

REMOVE BATTERY CLAMP COVER

2.

REMOVE THROTTLE BODY COVER

3.

REMOVE AIR CLEANER AND INTAKE AIR CONNEC-
TOR ASSEMBLY

4.

REMOVE NO.3 TIMING BELT COVERS 
(See page 

EM–16

)

5.

REMOVE IGNITION COILS (See page 

IG–5

)

6.

REMOVE RH CYLINDER HEAD COVER

Remove the 9 bolts,

 

seal washers and cylinder head cover.

7.

REMOVE LH CYLINDER HEAD COVER

(a)

Remove the oil dipstick for the transmission.

(b)

Disconnect the PCV hose.

(c)

Disconnect the engine wire clamp from the wire bracket
on the cylinder head cover.

(d)

Remove the 9 bolts, 9 seal washers and cylinder head
cover.

8.

SET NO.1 CYLINDER TO TDC/COMPRESSION

(a)

Turn the crankshaft pulley, and align its groove with timing
mark ”0” of the No.1 timing belt cover.

(b)

Check that the timing marks of the camshaft timing pul-
leys and timing belt rear plates are aligned.

If not, turn the crankshaft 1 revolution (360

°

) and align the mark

as above.

A05717

RH Cylinder Head

LH Cylinder Head

Front

A04457

RH Cylinder Head

LH Cylinder Head

Front

–

ENGINE MECHANICAL

VALVE CLEARANCE

EM–5

2584

9.

INSPECT VALVE CLEARANCE

(a)

Check only the valves indicated.

Using a feeler gauge, measure the clearance be-
tween the valve lifter and camshaft.

Record the out–of–specification valve clearance
measurements. They will be used later to determine
the required replacement adjusting shim.

Valve clearance (Cold):

Intake

0.15 – 0.25 mm (0.006 – 0.010 in.)

Exhaust

0.25 – 0.35 mm (0.010 – 0.014 in.)

(b)

Turn the crankshaft 1 revolution (360

°

) and align the mark

as above. (See procedure in step 8)

(c)

Check only the valves indicated as shown. Measure the
valve clearance. (See procedure in step (a))