NISSAN 300ZX 1984 Z31 Engine Fuel And Emission Control System User Guide

AIR FLOW SYSTEM DESCRIPTION
Air cleaner
VG30E engine (Without turbocharger) up roleno,,, FlCD
r
Valve
0 Intake air flow
C Exhaust gar flow
VGJOET engine (With turbocharger)
Vacuum control valve
Emergency relief valve
0 Intake air flow
Exhaust gar flow
cleaner
Turbbne
Turbocharger - unit- \Compresor SE F 608 B
EF & EC-11

AIR FLOW SYSTEM DESCRIPTION
TURBOCHARGER
The turbocharger is installed on the exhaust mani-
fold This system utilizes exhaust gas energy to
spin the turbine wheel which
is directly connected
to the compressor wheel The compressor supplies
pressurized air through the throttle chamber into
the intake manifold Thus, the turbocharger in-
creases charging efficiency and thereby increases
power and torque.
To prevent an excessive rise in the supercharging
pressure, the turbine speed
is maintained within a
safe range by controlling the amount of exhaust
gas that passes through the turbine This system
consists of
a by-pass valve which allows some of
the exhaust gas to by-pass the turbine and to flow
directly into the exhaust tube
Engine speed
From b==iF exhausi man2fold 0 Superchargang pressure 41 hqh
To intake
From air flo meter
h
To intake
From air flo meter
2 Bygars valve controller
3 Compressor
4 Turbine
SEF609B
EMERGENCY RELIEF VALVE
To prevent an abnormal rise in supercharging
pressure, and possible engine damage, in case
the
by-pass valve fails to open properly, an emergency
relief valve
is provided as a safety device on the
intake manifold
When the prwre in the Intake mandold IS below 52 0 kPa 1390 mmHg. 15 35 inHgl
Upper cover
When the prerrura tn the intake mandold IS above 520 kPa 1390 mrnHg, 15 35 mHg)
Atmosphere
Charged air pressure Charged air pressure
SEF6lOB
EF & EC-12

E.C.C.S. DESCRIPTION
E.C.C.S.
E C C.S. CONTROL UNIT
The E C C S control unit consists of a micro-
computer, connectors for signal input and output
and power supply, inspection lamps and diagnostic
mode selector The control unit controls the
amount
of fuel that is injected, ignition timing, idle
speed,
E G R , fuel pump operation, and feedback
of the mixture ratio
SEF611 B
CRANK ANGLE SENSOR
Crank angle sensor is a basic signal sensor for the
entire
E C C S It monitors engine speed and piston
position, and
it sends signals to the E C C S con-
trol unit for control of
fuel injection, ignition
timing, idle speed, fuel pump operation and
E G R
operation.
rnponents
Crank angle sensor has rotor plate and wave form-
ing circuit Rotor plate has
360 slits for 1" signal
(engine speed signal) and
6 slits for 120" signal
(crank angle signal) Light Emitting Diodes
(L
E D ) and Photo Diodes are built into wave
forming circuit
When
signal rotor plate passes the space between
the
L E D and Photo Diode, the slit of the signal
rotor plate alternately cuts the light which
is sent
to
the photo diode from the L E D This causes an
alternative voltage and
it is then converted into an
on-otf pulse by the wave forming circuit, which IS
sent to the control unit
Sealed mwr
Rotor head
.-- ? Lighremitring -. - diode 'I- 1- . ;-- , -
. A. -7. l.lll- i:--, .J
- I -, _,- I- ..
. ir- .I
4,,
Phatodlodel fi-. h- 1 ,h
Wave forming-' circurt '-Rotor piate
SEFBlJB
Rotor plate
SEF614B
EF & EC-13

E.C.C.S. DESCRIPTION
E.C.C.S. Components (Cont'd)
A
Air flow meter 0.
C
AIR FLOW METER
The air flow meter measures the mass flowrate of
intake air. Measurements are made in such
a man-
ner
that the control circuit emits an electrical out-
put signal
in relation to the amount of heat dissi-
pated from the hot wire placed
in the stream of
intake
air.
E F I relay
Battery source
Output voltage
Variable resistor
25 unit Ground
Self-cleaning ignition switch
Ground
El -
-
6- 31 27 35 1
w30 ECCS 6 comroi
F- 12 34 -
-
I SEF615B
SEFSlSB
The air flowing around the hot wire removes the
heat from
the hot wire The temperature of the hot
wire
is very sensitive to the mass flowrate of the
air.
The higher the temperature of the hot wire, the
higher
its resistance value This change in the
temperature (or. resistance)
IS determined by the
mass flowrate of the air. The control circuit
ac-
curately regulates current (I) in relation to the
varying resistance value
(RH) so that VA always
equals VB The air flow meter transmits an output
for voltage
VA to the control unit where the
output
is convened into an intake air signal.
I
Temperature compensation resistor
twire
Hot wore reststance
Temperature campenration resistance RA. RB Constant reSiiIanCe
RH RK
SEFS17B
I
EF & EC-14

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. Corn
FUEL TEMPERATURE SENSOR
The fuel temperature sensor is built into the pres-
sure regulator, and senses fuel temperature When
the fuel temperature
IS higher than the specified
level, the
E C C S control unit enriches fuel inject-
ed
Pressure regulator
Fuel temprature $ens
SEF625B
Do not remove fuel temperature sensor from pres-
sure regulator. Always replace as
an assembly.
DETONATION SENSOR (VG30ET engine only)
The detonation sensor
is attached to the cylinder
block and senses engine knocking conditions
A knocking vibration from the cylinder block is
applied as pressure to the piezoelectric element
This vibrational pressure
IS then converted into a
voltage signal which is delivered as output
Reed plate ,, ,-Weight
rTerminal
-.
Piezoelectric element
SEFSZSB
/-
FUEL INJECTOR
The
fuel injector is a small, precision solenoid
valve As the
E C C S control unit outputs an in-
lnents (Cont’d)
jection signal to each fuel injector, the coil built
into the injector pulls the needle valve back, and
fuel
is injected through the nozzle to intake mani-
fold The amount of fuel injected
is controlled by
the
E C C S control unit as an injection pulse
duration
<-Nozzle

LNeedle valve
SEF627B
POWER TRANSISTOR
The ignition signal from the
E C C S control unit
is amplified by the power transistor, which con-
nects and disconnects the coil primary circuit to
induce the proper high voltage in the secondary
circuit
SEFSZBB
IGNITION COIL
The ignition coil
IS a mold type
EF & EC-17

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
Fuel Injection Control
Temperature of engine Cylinder head temperature sensor
Density of oxygen in exhaust gas Exhaust gas sensor
Throttle valve idle position ' Throttle valve switch
Engine speed and piston position
Amount of intake air Air flow meter
ECCS
I I
I
control
Gear position unit NeutraVPark switch (VG30ET) I I
Vehicle speed
Start signal
Temperature of fuel
Battery voltage Battery
The E.C C S control unit calculates basic injection
pulse
width by processing signals from crank angle
sensor and air flow meter Receiving signals from
each sensor which detects various engine condi-
tions,
E C.C S control unit adds various enrich-
ments, which are pre-programmed
in the control
unit, to the basic injection amount. Thus, the op-
timum amount of fuel is injected through the
injectors.
1 ) Fuel enrichment
In the following each conditions, fuel is
enriched
e During warm-up
When starting
After idle
e When accelerating
e With heavy load
e When fuel temperature is high
.I Injector
Rlch
' \/ .-Warm-u~ enrichment
Cylmder head temperature (or fuel temperature1 SE F637 0
Enrichment rates for "when accelerating" and
"with heavy load" are pre-programmed for engine
speed and basic injection pulse
width
EF & EC-20