Isuzu N-Series. Manual — part 424
6E-32 EMISSION AND ELECTRICAL DIAGNOSIS
Notice:
The meaning of symbol marks are:
Connec-
tor 22 pin
1
EGR Cut Magnetic Valve Power Supply
×
❍
❍
2
Glow Relay
❍
❍
❍
3
Glow Indicator Lamp
❍
❍
❍
4
Rack Idle Position Out Put
5
Not be used
—
—
—
6
Not be used
—
—
—
7
Engine Coolant Temperature Sensor GND
❍
❍
❍
8
Engine Coolant Temperature Sensor SIG
❍
❍
❍
9
Engine Revolation Sensor GND
❍
❍
❍
10
Engine Revolation Sensor SIG
❍
❍
❍
11
VSS Magnetic Valve Power Supply
×
❍
❍
12
QWS Relay
❍
❍
❍
13
Aneroid Compensator Magnetic Valve
❍
❍
❍
14
Not be used
—
—
—
15
Not be used
—
—
—
16
Not be used
—
—
—
17
Not be used
—
—
—
18
Starter Switch
❍
❍
❍
19
Exhaust Brake Status Switch
❍
❍
❍
20
Not be used
—
—
—
21
Not be used
—
—
—
22
Not be used
—
—
—
Equipped
without
EGR and
VSS
Equipped with EGR and
VSS
Connector
Connector
number
Connector name
4HE1-XS
4HE1-XN
4HE1-XS
❍: Connect
BLANK: Not
×: Not Connect
EMISSION AND ELECTRICAL DIAGNOSIS 6E-33
Location of the Engine Control Module (ECM) Connector
Location of Data Link Connector (DLC)
Legend
A. 30 pins connector (green)
1. Engine control module (ECM)
B. 22 pins connector (green)
Legend
A. Right-hand drive
C. Terminal assignment of data link connector (DLC)
B. Left-hand drive
N6A1143E
N6A1665E
6E-34 EMISSION AND ELECTRICAL DIAGNOSIS
NO
TERMINAL NAME
6
DIAG CONTROL
7
CHECKER SIG
4, 5
CHECKER GND
N6A1666E
EMISSION AND ELECTRICAL DIAGNOSIS 6E-35
BRIEF EXPLANATION OF EMISSION AND ELECTRICAL CONTROL SYSTEM
MITICS (Mechanically Integrated Timing
and Injection Control System)
The Mechanically Integrated Timing and Injection rate
Control System (MITICS) utilizes mechanical control, in
comparison with TICS systems, which utilize electronic
control.
MITICS is equipped with the RLD-M type governor,
which contains a pre-stroke control mechanism.
With this, pre-stroke position (i.e., beginning of static in-
jection) can be varied to control injection timing and in-
jection rate (i.e., the fuel injection quantity injected from
the nozzle per cam angle degree).
This enables high injection rates1 in the low and medi-
um speed ranges through a short Injection interval, thus
contributing to higher engine torque and cleaner ex-
haust.
MITICS was developed in response to the demands of
medium sized diesel engines for low cost, low fuel con-
sumption, high output and cleaner emissions.
High injection rates using a short injection interval.
• The speed at which the injection pump plunger ris-
es slows as engine speed decreases and the pres-
sure inside the injection pipe decreases.
Because of this, the nozzle spray deteriorates and
makes it impossible to obtain the proper fuel - air
mixture.
To obtain the proper mixture at low and medium
speeds, it is necessary to increase the pressure in-
side the injection pipes using a short injection inter-
val.
• The left hand figure shows plunger speed and cam
lift in relation to cam angle. It can be seen from the
graph that plunger speed increases together with
cam lift.
MITICS varies the beginning of injection position at
low and medium speeds so that injection occurs
when the plunger speed increases during the latter
half of cam lift (shown by the bold line).
At high speeds, injection is performed when the
plunger speed decreases during the first half of
cam lift to prevent an excessive increase in injec-
tion pipe pressure.
This enables high pressures at low and medium
speeds with a fast plunger speed.
Thus, a fine fuel oil spray is injected into the cylin-
der from the nozzles within a short time to provide
the proper mixture for combustion, helping to in-
crease torque and keep exhaust emissions clean.
Legend
1. Injection pipe pressure
2. Engine speed
3. PE-AD type injection pump
N6A1145E
Legend
1. Plunger speed (m/sec)
2. Cam angle (degrees)
3. Cam lift (mm)
4. Plunger speed
5. Cam lift
N6A1146E
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