ESP NISSAN 300ZX 1984 Z31 Engine Fuel And Emission Control System Workshop Manual

FUEL FLOW SYSTEM DESCRIPTION
The amount of fuel to be injected is determined by
the injection pulse duration
as well as by a pressure
difference between fuel pressure and intake mani-
fold vacuum pressure. The
E.C C.S. control unit
controls only the injection pulse duration For this
reason,
the pressure difference between the fuel
pressure and intake manifold vacuum pressure
should be maintained
at a constant level Since the
intake manifold vacuum pressure varies with engine
operating conditions,
a pressure regulator IS placed
in the fuel line to regulate the fuel pressure in
response to changes
in the intake manifold vacuum
pressure
Fuel pump and damper
’ iFueirank
SEF604B
intake manifold 0 vacuum
a From fuel tank
Fuel chamber
SEF605B
Fuel presswe
EF & EC-10

E. C. C. S. DESCRIPTION
E.C.C.S. Corn1
Self-cleaning
After engine is stopped, the E C.C S control unit
heats up the hot wire to approximately
1,OOO"C
(1,832"F) to burn out dust which adhered to the
hot wire
- - 1 rec 5 rec
SEF618B
Self-cleaning operation
Condition _____~ ~
After running engine at above 1,500 rpm
After driving vehicle at above
20 kmlh
(12 MPH)
Cylinder head temperature is more than
115OC
(239°F)
Except above
Operation
Operates
Does not
operate
CYLINDER HEAD TEMPERATURE SENSOR
SEF6198
nents (Cont'd)
The cylinder head temperature sensor, built into
the cylinder head, monitors changes in cylinder
head temperature and transmits
a signal to the
E C C S control unit
The temperature sensing unit employs
a thermistor
which
is sensitive to the change in temperature
Electrical resistance
of the thermistor decreases in
response to the temperature
rise
Thermmor
U
SEF6208
EXHAUST GAS SENSOR
SEF621
The exhaust gas sensor, which is built into the
exhaust manifold, monitors the density
of oxygen
in the exhaust gas It consists of a closed-end tube
made
of ceramic zirconia and other components.
Porous platinum electrodes cover the tubes inner
and outer surfaces The closed-end
of the tube IS
exposed to the exhaust gas in the exhaust mani-
fold The outer surface
of the tube contacts the ex-
haust
gas while the inner surface contacts the air
EF & EC-15

E.C.C.S. DESCRIPTION
E. C. C. S. Corn1
In order to ensure the stable performance of the
exhaust
gas sensor, a ceramic heater is employed
inside the zirconia tube
,-Ceramic zirmnia tube
.- . .. . ... .. . . . . . .. .. --_
SEF622B
THROTTLE VALVE SWlTCl
The throttle valve switch is attached to the throttle
chamber and actuates in response
to accelerator
pedal movement
This switch has idle contact and full throttle con-
tact The idle contact closes when the throttle
valve
is positioned at idle and opens when it is at
any other position.
The full throttle contact
is used only for the
electronic controlled automatic transmission
SEF623B
Full throttle contact p0,nt
nents (Cont'd)
VEHICLE SPEED SENSOR
(VG30ET
engine only)
The vehicle speed sensor provides a vehicle speed
signal
to the E C.C S. control unit
Needle type speedometer models
The speed sensor consists of
a reed switch, which IS
installed in the speed meter unit and transforms
vehicle
speed into a pulse signal.
Magnetic line
\# Reed \I
i : !' sw17CI i N S"
Field 0 plate Field plate
SEF624B
Digital type speedometer models
The speed sensor consists of
an L E D , photo
diode, shutter and wave forming circuit.
Its princi-
ple
is the same as that of the crank angle sensor
011 seal
0 To speedometer cable
SEFS80B
EF & EC-16

E. C. C. S. DESCRIPTION
E.C.C.S. Corn1
AUXILIARY AIR CONTROL (A.A.C 1 VALVE
(VG30ET
engine)
The
A A C valve is attached to the intake collec-
tor The E C CS control unit actuates AAC
valve by ON/OFF pulse of approximately 160 Hz
The longer that ON duty is left on, the larger the
amount of
air that will flow through the A A C
valve
1
AV SEF630B
IDLE-UP SOLENOID VALVE (VG30E engine)
The idle-up solenoid valve is attached to the intake
collector The solenoid valve actuates to stabilize
idle speed when engine load
is heavy because of
electric load, power steering oil pump, etc.
7
idle speed adiuning screw
ldleup solenoid valve
SEF631 B
FICDJ solenoid valve
F I C D adjusling screw
nents (Cont'd)
E G R CONTROL VALVE
The E G R. control valve controls the quantity of
exhaust
gas to be led to the intake manifold
through vertical movement of the taper valve con-
nected to the diaphragm, to which vacuum
IS
applied in response to the opening of the throttle
valve.
SEF632B
When installing the E.G.R. guide tube, be careful
of its direction. Otherwise the distribution effi-
ciency of the exhaust gas will be reduced.
SEF689B
EF 8i EC-18

E. C. C. S. DESCRIPTION
E.C.C.S. Components (Cont’d)
E.G.R. CONTROL SOLENOID VALVE
E G R control solenoid valve cuts intake manifold
vacuum signal for
E G.R control The solenoid
valve actuates in response to the ON/OFF signal
from
the E C.C S control unit. When the solenoid
is off, vacuum signal from intake manifold is fed
into the
E G R control valve As the control
unit outputs an ON signal, the coil pulls the
plunger downward, and cuts the vacuum signal
9 Atmosphere
ToEGR control valve
From intake
SEF6336 0 manifold
FUEL PUMP
The fuel pump, which is located in the fuel tank, IS
a wet type pump where the vane rollers are directly
coupled to
a motor which is filled with fuel
1 Outlet A
AIR REGULATOR
Air regulator gives an air by-pass when the engine is
cold for the purpose of a fast idle during warm-up
SE F635 B
A bimetal, heater and rotary shutter are built into
the air regulator When the bimetal temperature
IS
low,
the air by-pass port is open As the engine
starts and electric current flows through a heater,
the bimetal begins to rotate the shutter
to close off
the by-pass port The air passage remalns closed
until the engine
is stopped and the bimetal tem-
perature drops
SEF636B
EF & EC-19

E. C. C. S. DESCRIPTION
Ignition Timing Control
Engine speed and piston position Crank angle sensor
Amount of intake air Air flow meter
Temperature of engine Cylinder head temperature sensor
Throttle valve idle position
Vehicle speed Vehicle speed sensor (VG30ETl 1 I I
Start signal Ignition switch
Engine knocking Detonation sensor
Battery voltage Battery ~
Ignition
timing is controlled, corresponding to the
engine operating conditions, by the
E C C S con-
trol unit that
is, as the optimum ignition timing in
each driving condition has been pre-programmed in
the control unit, the ignition timing
IS determined
by electrical signals processed in the unit
The signal from
E C C S control unit is trans-
mitted to power transistor, and controls ignition
timing
The retard system by detonation sensor
is designed
only for emergencies on VG30ET engines. The
basic ignition timing
is pre-programmed within the
anti-knocking zone, even
if recommended fuel is
used under dry conditions Consequently, the
retard system does not operate under normal
driving conditions
However,
if there engine knocking occurs, the
detonation sensor monitors knocking condition
and the signal is transmitted to the E.C.C S
control unit After receiving it, the control unit
retards the ignition timing to avoid the knocking
condition
Power transistor
EF & EC-23

E. C. C. S. DESCRIPTION
Start signal ’ Ignition switch
Throttle valve idle position
Neutral position t
Battery voltage Battery
Idle Speed Control (VG30ET engine)
Engine speed
Engine temperature
ECCS
control
Unlt
-
The idle speed is controlled by the E.C C S. control
unit, corresponding to the engine operating condi-
tions
The E C C S control unit senses the engine
condition and determines the best idle speed
at
each cylinder head temperature and gear position
The control unit then sends an electronic signal
corresponding
to the difference between the best
idle speed and the actual idle speed to the A A C.
valve.
I
,/ lAiC”ON”1 -‘I E .. -
P - 0 E 4 1 - - - -L- - - - - - lZN)
500 w
LAiT (”0”. A/C ”ON1
I -20 0 20 40 60 80 1M) 14) I321 168) 11041 1140) 1176) (212)
Cylinder head ternprature “C (OF1
SEF641B
Auxiliary air control valve
EF & EC-25

SELF-DIAGNOSIS
Self-diagni
The self-diagnostic system determines malfunctions
of signal systems such as sensors, actuators, and
wire harnesses based on the status of the input
signals received by the
E C C S control unit
A malfunction is displayed by both the red and
green
L E D s (Light Emitting Diodes).
Basically, self-diagnosis
is always performed when
the power
is furnished to the E C C S control
unit The self-diagnosis results
are retained in the
memory chip of the
E C C S control unit and are
displayed only when the diagnosis mode selector
(located on
the side of the E C C S. control unit) is
turned fully clockwise
The self-diagnostic system
is provided with func-
tions which display malfunctions being checked
as well as those which are stored in the memory
In
this sense, it is very effective in determing an
"intermittent" malfunction The results which
is
or was stored in the memory can be erased by
following the steps specified
A malfunctioning area is determined by the num-
ber of blinks of both the
red and green L E D s
First, the red L E D blinks and the green follows
The red L E D refers to the tenth digit while the
green
one refers to the unit digit. For example,
when the red L
E D. blinks three times and the
green
L E.D blinks twice, this implies number
"32" In this way, all problems are classified by
code numbers.
inspection lamps1 Diagnosis mode
SEF6508
Judging the selfdiagnosis results
1 When the ignition switch is turned "ON",
the diagnostic system judges
a malfunction
tic System
until the specified input signal is entered and
detected
as 0 K
(These input signals are not stored in the
memory
)
1) Vehicle speed sensor circuit (VG30ET engine)
When the vehicle speed exceeds
10 km/h
(6 MPH) and its corresponding signal is entered
2) Throttle valve switch (idle switch) circuit,
neutral switch circuit (VG30ET engine) and
air
conditioner switch circuit
After the ignition switch
is turned "ON" and
"ON-OFF"
signals from each switch are
entered
3) Start signal
After the engine has started and when start
signals "ON" and then "OFF" are entered
2 After the self-diagnostic system has detected
a malfunction, it continues to provide a mal-
function display until the memory
is erased
properly by the sepcified steps
1) Crank angle sensor circuit
When 1" or 120" signal is not entered after
the engine has started
When either 1" or 120" signal is not entered
often enough
2) Air flow meter circuit
When the air flow meter produces an abnormal-
ly high output voltage with the engine off
When the air flow meter produces an abnormal-
ly low output voltage with the engine running.
3) Cylinder head temperature sensor circuit
When the cricuit
is shorted or open
4) Ignition signal
When an ignition signal
is not produced on the
primary winding of the ignition coil after
the
engine has started
5) Fuel pump circuit
When current flowing through the E
C C.S
control
unit to drive the fuel pump IS too
small or too large while the engine
is operating.
6) Detonation sensor circuit (VG30ET engine)
When the circuit
is shorted with the engine
operating
at a speed of above 2,000 rpms
When the circuit is shorted or open
7) Fuel temperature sensor circuit
EF & EC-35