engine ISUZU TF SERIES 2004 Workshop Manual

6E–64 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR ECM AND
SENSORS
Engine Control Module (ECM)
The engine control module (ECM) is located flower
panel just under the passenger's seat.
The fuel quantity and injection timing related functions
are controlled by the pump control unit (PSG).
The engine control module (ECM) performs the
following functions.
Control of the ex haust gas re-circulation (EGR)
Control of the quick on start (QOS) glow control
system
Control of the A/C compressor
Ex ecution of the immobilizer function
Pump Control Unit (PSG) & Data Exchange
Between Control Module
The radial plunger distributor type injection pump uses
two control modules to ex ecute full control of the enginemanagement system.
Engine Control Module (ECM)
Pump Control Unit (PSG) = Pumpen Steuer Great
(German)
The pump control unit (PSG) receives signals from the
sensors inside the pump to determine the cam ring
rotation angle, the pump speed and the fuel
temperature .
These values are then compared to the desired values
sent by the engine control module (ECM) such as the
desired injection timing and the desired fuel injection
quantity.
The engine control module (ECM) processes all engine
data and data regarding the surrounding environment
received from ex ternal sensors to perform any engine
side adjustments.
Maps for both are encoded in both control units. The
control units input circuit process sensor data.
A Microprocessor then determines the operating
conditions and calculates set values for optimum
running.
The interchange of data between the engine control
module (ECM) and the pump control unit (PSG) is
perfumed via a CAN-bus system. The abbreviation CAN
stands for Controller Area Network. By having two
separate control modules, the high pressure solenoid
valve. This prevents the discharge of any disturbing
signals.
The information ex change between the two control
modules takes place via two means.
Via analogue signal leads
Via the CAN-bus
The analogue signal leads are used to ex change the
following information.
Engine speed signal (ECM terminal 91)
Pump Speed (ECM terminal 105)
Fuel Cutoff solenoid valve signal (MAB signal) (ECM
terminal 105)
The engine speed signal is sent from the ECM to PSG
based on the input from the crank shaft position (CKP)
sensor.
The analogue CKP sensor signal is converted by the
ECM into a square wave signal.
The fuel cutoff solenoid valve signal is also referred to
as MAB signal.
MAB in this case, refers to the German abbreviation
Magnet ventil ABschaltung that stands for high pressure
solenoid v alv e cut off.
The MAB signal wire is used for two purposes.
-As a reference for the engine control module (ECM) for
the pump speed (back up for the CKP sensor).
-To turn Off the engine.
Sel f Dia gn osis / Interfa ce / Si gn al
To High Pressure Solenoid
Engine Speed
Injection Timing
Accelerator Pedal
Injection Quantity
In ta ke Air Temperat ure
Response Signal
Ma ss Air Flow
Additional Signal
Others

Additional Operations To Timing Control Valve (TCV)
Engin e
Con trol
Modu le
(ECM) Cam Rin g Rota tiona l Angle
Fuel Temper atu re
High Pressure
Solenoid Valve
Pump
Con tr ol Fuel Inject ion
Unit (Mechanical)
(PSG)

Ti m i n
g Devi ce

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–65
The following signals are ex changed via the CAN-bus:
From ECM to PSG
Desired injection quantity
Desired injection timing
Engine speed
From PSG to ECM
Fuel temperature
Pump speed
Cylinder identifier
Control pulse (actual injection quantity + actual
injection timing)
PSG status
Mass Air Flow (MAF) Sensor & Intake Air
Temperature (IAT) Sensor
The mass air flow (MAF) sensor is part of the intake air
system.
It is fitted between the air cleaner and turbocharger and
measure the mass air flowing into the engine.
The mass air flow (MAF) sensor uses a hot film element
to determine the amount of air flowing into the engine.
The mass air flow (MAF) sensor assembly consist of a
mass air flow (MAF) sensor element and an intake air
temperature sensor that are both ex posed to the air flow
to be measured.
The mass air flow (MAF) sensor element measures the
partial air mass through a measurement duct on the
sensor housing.
Using calibration, there is an ex trapolation to the entire
mass air flow to the engine.The IAT sensor is a thermistor. A temperature changes
the resistance value. And it changes voltage. In other
words it measures a temperature value. Low air
temperature produces a high resistance.
The ECM supplies 5 volts signal to the IAT sensor
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the air temperature
is cold, and it will be low when the air temperature is
hot.
(1) Air Cleaner Case
(2) Mass Air Flow (MAF) & Intake Air Temperature
(IAT) Sensor

1 2
Characteristic of IAT Sensor -Reference-
10 100 1000 10000 100000
-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110
Intake Air Temp. (deg. C) (Tech2 Reading)
Resistance (ohm) (Solid Line)

6E–66 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Throttle Position Sensor (TPS)
The TPS is a potentiometer connected to throttle shaft
on the throttle body. It is installed to the main TPS and
idle switch.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve. As the throttle valve opens, the output
increases so that the output voltage should be high.
The engine control module (ECM) calculates fuel
delivery based on throttle valve angle.
Crankshaft Position (CKP) Sensor
The CKP sensor is located on top of the flywheel
housing of the flywheel and fix ed with a bolt.
The CKP sensor is of the magnet coil type. The
inductive pickup sensors four gaps in the flywheel
ex citer ring and is used to determine the engine speed
and engine cylinder top dead center (TDC). (1) Throttle Position Sensor (TPS)
(2) Idle Switch

1 2
Characteristic of TPS -Reference-
0 0.51 1.52 2.53 3.54 4.5
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Pedal Position (%) (Tech2 Readin
g
Output Voltage (V)
(1) Crankshaft Position (CKP) Sensor
(2) Fly wheel with sensor slot

1 2

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–67
Engine Coolant Temperature (ECT) Sensor
The ECT sensor is a thermistor. A temperature changes
the resistance value. And it changes voltage. In other
words it measures a temperature value. It is installed on
the coolant stream. Low coolant temperature produces
a high resistance.
The ECM supplies 5 volts signal to the ECT sensor
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the engine
temperature is cold, and it will be low when the engine
temperature is hot.
Vehicle Speed Sensor (VSS)
M/T & A /T 4WD
A/T 2WD
The VSS is a magnet rotated by the transmission output
shaft. The VSS uses a hall element. It interacts with the
magnetic field treated by the rotating magnet. It outputs
pulse signal. The 12 volts operating supply from the
meter fuse.
The engine control module (ECM) calculates the vehicle
speed by VSS.
The 2WD model fitted with automatic transmission,
vehicle speed sensor signal is transmitted to from the
TCM to the ECM via vehicle speed meter. (1) Engine Coolant Temperature (ECT) Sensor
(2) Thermo Unit for Water Temperature Gauge
12
Characteristic of ECT Sensor -Reference-
10 100 1000 10000 100000
-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Engine Coolant Temp (deg. C) (Tech2 Reading)
Resistance (ohm) (Solid Line)

6E–68 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR EGR
(EXHAUST GAS RE-CIRCULATION)
The 4JA1-TC & 4JH1-TC engine with Euro 3 regulation
is equipped with the EGR cooler. The EGR cooler
reduces the temperature of the air being drawn into the
engine and the combustion temperature. This results in
reducing nitrogen ox ide (Nox ) emissions. The 4JH1-TC
engine ex cept Euro 3 regulation, it does not have EGR
cooler. It has steel EGR pipe instead of the cooler.
The amount of EGR is controlled by EVRV (electrical
vacuum regulating valve) via the engine control module
(ECM) command signal depends on the following
inputs.
Engine speed
Injection quantity
Mass air flow
Intake air temperature
Coolant temperature
Barometric pressure (1) EGR Valve
(2) EGR Cooler (Euro 3) / EGR Pipe (Except Euro
3)
(3) Intercooler
(4) Intake Manifold
(5) Ex haust Manifold
(6) Waste Gate
(7) Fresh Air
(8) Ex haust Gas
(9) Turbocharger
123
(1) To EGR Valve
(2) From Vacuum Pump
(3) EGR EVRV
(4) EGR Cooler
(5) Thermo Valve
(6) EGR Valve
4 5 6

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–69
The EVRV is shaped to control vacuum applied to the
diaphragm chamber of the EGR valve based on duty
signal sent from the ECM. The duty ratio is the time that
the EVRV is opened to one cooperate EVRV operating
cycle. A duty ratio change of 90% to 10 % is EGR
amount control.

7.1m s





Time 0. 7m s Off duty 10% =EGR Pulse Ratio 10%
7.1ms




Ti m e 6.4ms Off duty 90% =EGR Pulse Ratio 90%

6E–70 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR INJECTION
PUMP
Outline
Instead of the previous face cam type, the radial plunger
distributor type injection pump utilizes a cam ring to
enable fuel injection at high-pressures, marking it
suitable for small, high-speed direct injection diesel
engines. This pump was developed to provide the most
suitable fuel injection quantity and injection timing to
satisfy the demand for engine reliability, driveability, low
smoke, low noise, high output and clear ex haust
emissions.
Cross-section View
(1) Drive Shaft
(2) Feed Pump
(3) Pump Camshaft Speed Sensor
(4) Pump Control Unit (PSG)
(5) Distributor Head
(6) Constant Pressure Valve (CPV) Holder
(7) High Pressure Solenoid Valve
(8) Constant Pressure Valve (CPV)
(9) Timing Control Valve (TCV)
(10) Timer
(11) Radial Plunger High Pressure Pump
(1) Drive Shaft
(2) Feed Pump
(3) Pump Camshaft Speed Sensor
(4) Pump Control Unit (PSG)
(5) Distributor Head
(6) Constant Pressure Valve (CPV) Holder
(7) High Pressure Solenoid Valve
(8) Constant Pressure Valve (CPV)
(9) Timing Control Valve (TCV)
(10) Timer
(11) Radial Plunger High Pressure Pump

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–71
Low Pressure Fuel Circuit
The low pressure fuel circuit must supply sufficient fuel
to the high pressure fuel circuit. The main components
are the feed pump, the regulating valve and the
overflow valve. (1) Rotor Shaft
(2) Radial Plunger
(3) High Pressure Passage
(4) Low Pressure Inlet
(5) Distributor Slit
(6) Valve Needle
(7) Barrel
(8) Annular Passage
(9) Fuel Return
(10) High Pressure Solenoid Valve
(11) High Pressure Outlet
(12) Diaphram Chamber
(13) Accumulator Diaphram
(1) Fuel Suction
(2) Regulating Valve
(3) Overflow Valve
(4) Feed Pump
(5) To Fuel Tank

6E–72 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
High Pressure Fuel Circuit
In addition high pressure generating device, the high
pressure circuit also consists of fuel piping, and devices
to set the beginning of injection and fuel injection
quantity.
The main components are as follows.
High pressure generation: Radial Plunger High
Pressure Pump
Fuel distribution: Distributor Head
Beginning of injection timing: Timing Device
Prevention of secondary injection: Constant Pressure
Valve (CPV)
Pump Camshaft Speed Sensor
When the drive shaft rotates, the pump camshaft speed
sensor receives signal form the sensor wheel, and an
electric pulse is sent through the flex ible connecting
harness to the pump control unit (PSG).
From these signals the pump control unit (PSG) can
determine the average pump speed and the momentary
pump speed.
The pump camshaft speed sensor is mounted to the
cam ring. Thus, the relationship between the cam ring
and the pump camshaft speed sensor signal is
constant. (1) Pump Control Unit (PSG)
(2) Distributor Head
(3) High Pressure Solenoid Valve
(4) Constant Pressure Valve (CPV)
(5) Radial Plunger High Pressure Pump
(1) Pump Camshaft Speed Sensor
(2) Sensor Wheel
(3) Pump Camshaft Speed Sensor Retaining Ring
(4) Flex ible Connector Harness
(5) Drive Shaft

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–73
The pump camshaft speed sensor signal is utilized for
the following purposes.
To determine the momentary angular position of the
cam ring.
To calculate the actual speed of the fuel injection pump.
To determine the actual timing plunger position.
The pump camshaft sensor signal has a tooth gap, and
the crankshaft position (CKP) sensor on the flywheel
housing is used as a reference signal of engine top
dead center (TDC) for the start timing of fuel delivery or
injection which is to be set.High Pressure Solenoid Valve
Fuel injection quantity control is performed from the
beginning of pressure delivery at the beginning of cam
lift until the high pressure solenoid valve opens at the
end of pressure delivery.
This interval is called the pressure delivery interval.
Accordingly, the interval that the high pressure solenoid
valve is closed determines the fuel injection quantity
(high pressure fuel supply ends when the high pressure
solenoid valve opens).
-Cam Ring Angle
Sensor -Pump Speed
Wheel -Timer PositionPump
Control
Unit
(PSG)Pump
Camshaft
Speed
Sensor
(1) Valve Needle
(2) Magnet Anchor
(3) Coil
(4) High Pressure Passage