Diesel Throttle Outline (1CD-FTV/15B-FTE)

The diesel throttle is mounted on the

intake manifold. The throttle valve, which
Diesel throttle control motor
operates independently from the accel-
Throttle valve
erator pedal, uses the diesel throttle
Engine speed signal
control motor (step motor) to regulate
Engine
Water temp. Signal the throttle opening accordance with the
ECU Accelerator pedal position signal signals received from the ECU.
Atmosphere pressure signal Purpose :
1. Ensures an optimal amount of EGR
volume throughout the operating
range by increasing the intake mani-
fold vacuum.
2. Reduces the intake noise and vibra-
tion by closing the throttle valve at
idle.
3. Reduces vibrations by fully closing
the throttle when stopping the engine
in order to reduce the amount of air
intake volume.
(1/2)

Diesel Throttle Operation

1. When the engine is running, the opening of the throttle
is optimally adjusted according to the engine speed,
engine load conditions, and the EGR volume.
2. When the engine is stopped, the throttle closes fully to
shut off the intake of air. By minimizing the compres-
sion in the cylinder, vibrations that occur when stop-
ping the engine are reduced.
(2/2)

REFERENCE
Intake Constrictor Control (1KZ-TE)
Chamber A
Chamber B
The intake constrictor control contains a
Main valve main valve and a sub valve. The main
Accelerator Actuator
pedal valve operates with the accelerator
pedal and the sub valve operates with
Atmosphere
the actuators that function with two
from Vacuum pump VSVs (VSV1 and VSV2), which operate
in accordance with the signals received
from the ECU.
Sub valve (1/1)
Atmosphere

Throttle position signal

Engine
Engine speed signal
Water temp. signal ECU Ignition switch

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Intake Shutter Outline and Operation of Intake Shut-
ter
Actuator The intake shutter is mounted on the
Intake
shutter intake manifold. The intake shutter is
from Vacuum pump fully open when the engine is operating.
To stop the engine, the VSV operates in
Atmosphere accordance with the signals from the
Engine ECU, and the actuator closes the intake
lgnition switch
ECU shutter. As a result, the amount of vibra-
tion is reduced when the engine is
stopped.

REFERENCE
VSV (Vacuum Switching Valve)
to Actuator Signals received from the ECU cause the VSV to switch
the pressure applied to the actuator between atmospheric
from Vacuum
pump
and vacuum pressures.
(1/1)

Atmosphere

EGR (Exhaust Gas Recirculation) EGR (Exhaust Gas Recirculation)

System

Vacuum regulator valve In the EGR system, the ECU controls

Throttle position sensor the vacuum regulator valve based on the
Vacuum Pump
signals that are sent by various sensors,
Engine speed sensor
in order to operate (open and close) the
ECU
Water temp. sensor EGR valve.
This causes a portion of the post-com-
Intake manifold pressure
signal
bustion gases to recirculate through the
Intake
intake manifold to slow down the com-
EGR
valve bustion speed.
Exhaust This lowers the combustion tempera-
manifold
Vacuum damper ture and reduces the generation of nitro-
gen oxides.
Through the adoption of the diesel throt-
tle, it has become possible to increase
the intake manifold pressure in order to
stabilize the EGR volume.
(1/1)

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 Vacuum Regulator Valve
from Vacuum pump The vacuum regulator valve operates in accordance with
to EGR valve the signals from the ECU to turn ON/OFF the vacuum
(generated by the vacuum pump) that actuates the EGR
valve.
(1/1)

Atmosphere

EGR Valve
The vacuum that is sent by the vacuum regulator valve
operates (opens and closes) the EGR valve to introduce
the post-combustion gases into the intake manifold.
(1/1)

EGR gas
EGR valve
Intake air

Operation of EGR System

The operation of the EGR is stopped under the conditions listed below in order to ensure drivability and reduce
black smoke.
• When the coolant temperature is low.
• When the vehicle is being driven under high-load conditions.
• When the engine is decelerating (the EGR operates during idle).
• When the vehicle is being driven at high altitudes.
(1/3)

On 15B-FTE and 1HD-FTE engines, the mounting posi-

EGR valve EGR valve tion of the EGR valve has been improved in order to pre-
vent its performance from being affected by the intake air
temperature.
(2/3)

E/G E/G

15B-FTE engine Ordinary engine

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 On the 15B-FTE engine, a dual construction EGR pipe
has been adopted. The coolant water flows along the out-
side of the pipe to cool the EGR gases. Thus, the intake
air is prevented from being warmed by the EGR gases.
EGR gas (3/3)
In
Out
A

A
Water

A-A cross section

Service Hint Intake Shutter Inspection

To inspect the intake shutter, connect a vacuum gauge to
the diaphragm, and verify that the actuator rod moves
when the specified amount of vacuum is applied to it.

Measure the resistance between the VSV terminals for

the intake shutter.
Ohmmeter (1/1)

Continuity

Diesel Throttle Inspection

An inspection of the diesel throttle consists of an inspec-
tion of the throttle motor.
Remove the throttle motor connector and measure the
resistance between the specified terminals.
(1/1)

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Exercise

These are the pre-course study materials for the Frequent Service Job Course. The objective of this course
is to learn the work procedure and points of frequent service jobs. In the pre-course study, you will study the
basic knowledge needed for repair work, and the basic mechanism and operation of automobiles. After you
finish studying all of the chapters, please take the Examination.

Chapter All Next Chapter All

Answers Answers
Correct Correct
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related text for review related text for review

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Question- 1
Mark each of the following statements True or False.

No. Question True or False Correct Answers

1 The EGR volume can be stabilized by regulating the diesel throttle. True False

2 The diesel throttle opens fully to reduce vibration when stopping True False
the engine.

While the engine is at idle, the throttle valve of the diesel throttle
3 True False
opens wide to stabilize the idle speed.

Question- 2
The following statements pertain to the intake shutter. Mark each of the following statements True or False.

No. Question True or False Correct Answers

1 Reduces vibrations that occur when stopping the engine. True False

2 The intake shutter is operated by a step motor. True False

3 The intake shutter is operated by a diaphragm. True False

4 The intake shutter is operated by ECU signals. True False

Question- 3
Mark each of the following statements True or False.

No. Question True or False Correct Answers

1 The EGR system reduces the generation of nitrogen oxides. True False

An engine that is equipped with a diesel throttle can raise its intake
2 True False
manifold vacuum to stabilize the EGR volume.

The EGR valve is actuated by a motor in accordance with ECU sig-

3 True False
nals.

After the engine has warmed up, the EGR operates at idle. How-
4 ever, when the vehicle is operating at high-load conditions, the oper- True False
ation of the EGR stops to reduce the emission of black smoke.

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