Service Manuals, User Guides, Schematic Diagrams or docs for : . Car Manuals Nissan 300ZX 1984-1985,1988,1990,1994-1996 Approved 1988 Engine Fuel & Emission

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EMISSION CONTROL SYSTEM

SECTION EFaEC
CONTENTS
PRECAUTIONS ...................................................... EF & EC- 3
ENGINE AND EMISSION CONTROL PARTS LOCATION .................. EF & EC- 4
E.C.C.S. DIAGRAM .................................................. EF & EC- 5
E.C.C.S. CHART ..................................................... EF&EC- 7
FUEL FLOW SYSTEM DESCRIPTION .................................. EF & EC- 9
AIR FLOW SYSTEM DESCRIPTION .................................... EF & EC- 10
E.C.C.S. CIRCUIT DIAGRAM .......................................... EF & EC- 11
E.C.C.S. WIRING DIAGRAM .......................................... EF & EC- 12
E.C.C.S. DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EF & EC- 14
DIAGNOSTIC PROCEDURE ........................................... EF & EC- 31
SELF.DIAGNOSIS .................................................... EF & EC- 61
ELECTRONIC CONTROL SYSTEM INSPECTION ......................... EF & EC- 82
CRANK ANGLE SENSOR ......................................... EF & EC- 84
AIR FLOW METER .............................................. EF & EC- 86
CYLINDER HEAD TEMPERATURE SENSOR ........................ EF & EC- 88
VEHICLE SPEED SENSOR ........................................ EF & EC- 90
IGNITION SIGNAL .............................................. EF & EC- 92
FUEL PUMP .................................................... EF & EC- 94
IDLE SWITCH .................................................. EF & EC- 96
ENGINE CONTROL UNIT ........................................ EF & EC- 98
...............................................
E.G.R. FUNCTION EF & EC-100
EXHAUST GAS SENSOR ......................................... EF & EC-104
DETONATION SENSOR .......................................... EF & EC-106
EXHAUST GAS TEMPERATURE SENSOR .......................... EF & EC-108
FUEL TEMPERATURE SENSOR ................................... EF & EC-112
THROTTLE SENSOR ............................................. EF & EC-114
INJECTOR LEAK ................................................ EF & EC-116
START SIGNAL ................................................ EF & EC-118
INJECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E F & E C.120
POWER SOURCE & GROUND CIRCUIT FOR E.C.U. . . . . . . . . . . . . . . . . . EF&EC-122
Contents (Cont'd)
A.I.V. CONTROL SOLENOID VALVE ............................... EF & EC-124
E.G.R. CONTROL SOLENOID VALVE .............................. EF & EC-126
IDLE-UP SOLENOID VALVE ...................................... EF & EC-128
A.A.C. VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EF & EC-130
NEUTRAL/INHIBITOR SWITCH .................................... EF & EC-132
P.R. CONTROL SOLENOID VALVE ................................ EF & EC-134
AIR REGULATOR ............................................... EF & EC-136
E.C.U. INPUT/OUTPUT SIGNAL INSPECTION ........................... EF & EC-138
MIXTURE RATIO FEEDBACK SYSTEM INSPECTION .................... EF & EC-143
FUEL SYSTEM INSPECTION .......................................... EF & EC-148
TURBOCHARGER INSPECTION ....................................... EF & EC-151
EVAPORATIVE EMISSION CONTROL SYSTEM .......................... EF & EC-153
E.G.R. SYSTEM INSPECTION ......................................... EF & EC-155
CRANKCASE EMISSION CONTROL SYSTEM ............................ EF & EC-156
A.I.V. SYSTEM INSPECTION .......................................... EF & EC-157
SERVICE DATA AND SPECIFICATIONS (S.D.S.) ......................... EF & EC-159

When you read wiring diagrams:
Read GI section. "HOW TO READ WIRING DIAGRAMS .
See EL section. "POWER SUPPLY R0UTING"for power distribution circuit .

EF & EC-2
PRECAUTIONS

E.C.U. WIRELESS EQUIPMENT
a Do not disassemble E.C.C.S. control When installing C.B. ham radio or a
unit. mobile phone, be sure to observe the
a Do not turn diagnosis mode selector following as it may adversely affect
forcibly. electronic control systems depending
a Do not disassemble the E.C.U. on i t s installation location.
BATTERY (the E.C.C.S. control unit). 1) Keep the antenna as far as possible
* Always use a 12 volt battery as Ifa battery terminal i s disconnect- away from the electronic control
power source. ad, the memory will return t o the units.
Do not attempt t o disconnect ROM value. The E.C.C.S. will now 2) Keep the antenna feeder line more
battery cables while engine is start to self-control at its initial than 20 em (7.9 in) away from the
running. value. Engine operation can vary harness of electronic controls.
slightly when the terminal is discon- Do not let them run parallel for a
nected. However, this is not an long distance.
indication of a problem. Do not 3) Adjust the antenna and feeder line
replace parts because of a slight so that the standing-wave ratio can
be kept smaller.
4) Be sure to ground the radio to vehicle
INJECTOR
Do not disconnect injector
harness connectors with
engine running.
Do not apply battery power
directly t o injectors.

FUEL PUMP
a Do not operate fuel pump when
there is no fuel in lines.
a Tighten fuel hose clamps t o the
specified toque.
E.C.C.S. PARTS HANDLING
Handle air flow meter care-
fully to avoid damage. E.C.C.S. PARTS HANDLING
Do not disassemble air flow a Securely connect E.C.C.S. harness
WHEN STARTING
meter. a Do not depress accelerator pedal connectors.
Do not clean air flow meter A poor connection can cause an ex-
when starting.
with any type of detergent. tremely high (surge) voltage to
a Immediately after starting, do
Do not disassemble auxiliary not rev up enigne unneces- develop in coil and condenser, thus
air control valve (VG30ET sarily. resulting in damage t o ICs.
engine). a Do not rev up engine just prior Keep E.C.C.S. harness a t least 10
Even a slight leak in the air in- cm (3.9 in\ away from adjacent
t o shutdown.
take system can cause serious harnesses, to prevent an E.C.C.S.
problems. system malfunction due to receiving
Do not shock or jar the crank external noise, degraded operation
angle sensor. of ICs. etc.
a Keep E.C.C.S. parts and harnesses
dry.
Before removing parts, turn off
ignition switch and then disconnect
battery ground cable. SEF179F

EF 8t EC-3
ENGINE AND EMISSION CONTROL PARTS LOCATION

A.I.V. unit A.I.V. control
solenoid valve
SEF3570

EF % EC-4
I
E.C.C.S. DIAGRAM

VG30E engine (Without turbochargar)

SEF358G

EF %t EC-5
E.C.C.S. DIAGRAM

VG30ET engine (With turbocharger)

SEF359G

EF & EC-6
E.C.C.S. CHART

VG30E Engine (Without turbocharger)
Crank angle sensor b
Fuel injection &
Injectors
mixture ratio control

Air flow meter P

Ignition timing control Power transistor

b
A.I.V. control A.I.V. control solenoid valve

Throttle valve sensor
(Except nonCalifornia M K ' E.C.C.S.
model1 control Fuel pressure regulator
Fuel pressure control
(Non-CaliforniaA K model: Only control unit control solenoid valve
for automatic transmission1 V L 1

Fuel temperature sensor
1 b

Fuel pump control Fuel pump
~

Headlamp switch
Cooling fan switch b
Power steering oil pressure switch
Air regulator control Air regulator

1Battery voltage

b
Exhaust gas sensor
heater control
" I
Exhaust gas sensor

Air flow meter wire
Air flow meter
Exhaust gas temperature sensor cleaning control
f Y I I
(California model only1

Exhaust gas sensor Inspection lamps
nonitor & self-diagnosis (On the control unit)

EF % EC-7
I
-Crank angle sensor

Air flow meter

Ignition switch

Idle switch

Throttle valve sensor

Throttle valve sensor
(Except nonCalifor
(Non-California A i l model: Only control
for automatic transmission)

Air conditioner switch

Fuel temperature sensor
E.C.C.S. CHART

,E.C.C.S.

b
control
unit
\
-
Fuel injection &
mixture ratio control

--
Ignition timing control

Idle speed control

E.G.R. control

A.I.V. control

A
Fuel pressure control

Fuel pump control

Air regulator control
L

I
Injectors

Power transistor

Auxiliary air cone01
(A.A.C.) valve

E.G.R. control solenoid valve

A.I.V. control solenoid valve

Fuel pressure regulator
control solenoid valve

Fuel pump

Air regulator
I
I

Detonation sensor
I
Exhaust gas sensor Exhaust gas sensor
heater control

Air flow meter wire
Air flow meter
cleaning control
Exhaust gas temperature sensor
(California model only)

Exhaust gas sensor Inspection lamps
monitor & self-diagnosi (On the control unit)
I

EF & EC-8
FUEL FLOW SYSTEM DESCRIPTION

VG30E engine (Without turbocharger)
Prerwre regulator
control ralenoid valve

-Fuel filler cap
with vacuum
relief valve

SEF937F

EF & EC-9
AIR FLOW SYSTEM DESCRIPTIQN

Vacuum control valve

Throttle valve1
I
-A.I.V. control solenoid valve

Air cleaner

0: Intakeairflow
: Exhaust gas flow
SEF1861

VG30ET engine (With turbocharger) F,I.C,D, valve, r A A . C . valva

Vacuum control valve

Emergency relief valve

B y g a s vdlw controller

ro1 solenoid valw

a : Intake air flow
: Exhaustgasflow
SEF1871

EF & EC-10
E.C.C.S. CIRCUIT DIAGRAM

E.C.C.S. CONTROL UNIT

SEF155G

EF & EC-11
E.C.C.S. WIRING DIAGRAM

EF 81 EC-12
E.C.C.S. WIRING DIAGRAM

I E.C.C.S. CONTROLVNlT
I

GROUND

SEF156G
E.C.C.S. DESCRIPTION

Components
E.C.U. (E.C.C.S. control unit)
The E.C.U. consists of a microcomputer, inspection lamps,
a diagnostic mode selector, and connectors for signal input and
output, and for power supply. The unit has control of the engine.

SEF6ll8

CRANK ANGLE SENSOR
The crank angle sensor is a basic component of the entire
E.C.C.S. It monitors engine speed and piston position, and sends
t o the E.C.U. signals on which the controls of fuel injection,
ignition timing and other functions are based.
The crank angle sensor has a rotor plate and a wave forming cir-
cuit. The rotor plate has 360 slits for 1" signal (crank angle sig-
nal) and 6 slits for 120" signal (engine speed signal). Light
Emitting Diodes (L.E.D.) and Photo Diodes are built in the wave
forming circuit Rotor plate
SEF613B forming circuit.
When the rotor plate passes the space between the L.E.D. and
the Photo Diode, the slits of the rotor plate continually cut the
light which is sent t o the photo diode from the L.E.D. This
causes generating rough-shaped pulses. They are then converted
into on-off pulses by the wave forming circuit, which are sent t o
the E.C.U.

Rotor plate SEFE148

AIR FLOW METER
+ The air flow meter measures the mass flow rate of intake air.
emery
sourcd Measurements are made i n such a manner that the control circuit

Airflw
E-

" Ground
Ovtput MltaQe
Variable resistor
-
-30
31

E.C.C.S.
emits an electrical output signal i n relation to the amount of heat
dissipated from the hot wire placed in the stream of intake air.
control

- The air flowing around the hot wire removes the heat from the
meter D 26

Selfcleaning unit
12 hot wire. The temperature of the hot wire is very sensitive to the
Ground
C mass flow rate of the air. The higher the temperature of the hot
-1 1
- I wire, the higher i t s resistance value. This change in the tempera-
I 'SEF646E ture (or: resistance) is determined by the mass flow rate of the
Temperature I air. The control circuit accurately regulates current (I)in relation
mmpensation resist t o the varying resistance value (RH ) so that V always equals
,
V B .The air flow meter transmits an output for voltage V, to the
ot wire
Air flow control unit where the output is converted into an intake air
signal.
Also, this air flow meter has self-burning off system in order t o
make hot wire clean.
RH : Hot wire red
RK : Temperature mmpensation
resistance
RA. R s : Constant resistance SEF617B.

EF & EC-14
E.C.C.S. DESCRIPTION
Components (Cont'd)
CYLINDER HEAD TEMPERATURE SENSOR
The cylinder head temperature sensor, built into the cylinder
head, moniton changes in cylinder head temperature and trans-
mits a signal to the E.C.U.
The temperature sensing unit employs a thermistor which i s
sensitive to the change in temperature. Electrical resistance of
the thermistor decreases in response to the temperature rise.

I IDLE SWITCH
Idlecontan . The idle switch is attached to the throttle chamber and actuates
in response t o accelerator pedal movement.
This switch has idle contact and full throttle contact. The idle
contact is used for engine control. It closes when the throttle
valve is positioned a t idle, and opens when it is a t any other
position.

SEF903D

FUEL INJECTOR
R The fuel injector is a small, precision solenoid valve. As the
E.C.U. outputs an injection signal to each fuel injector, the coil
built into the injector pulls the needle valve back, and fuel is
a injected through the nozzle to intake manifold. The amount of
fuel injected is controlled by the E.C.U. as an injection pulse
duration.

SEF4840

FUEL TEMPERATURE SENSOR
Pressure regulatol
The fuel temperature sensor i s built into the pressure regulator,
and senses fuel temperature. When the fuel temperature is higher
than the specified level, the E.C.U. enriches fuel injected.
Do not remove fuel temperature sensor from pressure regulator.
Always replace as an assembly.

SEF626U

Outlet FUEL PUMP
0
The fuel pump with a fuel damper is an in-tank type, that is the
pump and damper are located in the fuel tank. The vane rollers
are directly coupled to a motor which i s cooled by fuel.

0
Inlet SEF043C

EF & EC-15
-

E.C.C.S. DESCRIPTION
Components (Cont'd)
I Idle weed adiusring screw1 I IDLE-UP SOLENOID VALVE [VG30E]
The idle-up solenoid valve is attached t o the intake collector.
Idle-up solenoid Y
The solenoid valve actuates t o stabilize idle speed when engine
load is heavy because of electric load, power steering oil pump,
etc.

I
solenoid valve
F.I.C.O. adjusting screw
SEFIOOC

A.A.C. (AUXILIARY AIR CONTROL) VALVE LVG30ETl
The A.A.C. valve is attached to the intake collector. The E.C.U.
.I.C.O. solenoid valw
actuates the A.A.C. valve b y an ON/OFF pulse of approximately
160 Hz. The longer that ON duty is left on, the larger the
le wd
e
juning screw amount of air that will flow through the A.A.C. valve.

DETONATION SENSOR IVG30ETl
The detonation sensor is attached to the cylinder block and
senses engine knocking conditions.
A knocking vibration from the cylinder block is applied as pres-
sure t o the piezoelectric element. This vibrational pressure is
then converted into a voltage signal which is delivered as output.

I SEF626B

AIR REGULATOR
-Slide olate
The air regulator provides an air by-pass when the engine is cold
for the purpose of a fast idle during warm-up.
A bimetal, heater and rotary shutter are built into the air regu-
lator. 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 t o close o f f the
by-pass port. The air passage remains closed until the engine. is
stopped and the bimetal temperature drops.
SEF636B

A.I.V. (AIR INDUCTION VALVE)
The air induction valve sends secondary air to the exhaust mani-
fold, utilizing a vacuum caused b y exhaust pulsation in the
exhaust manifold. When the exhaust pressure is below at-
mospheric pressure (negative pressure), secondary air is sent t o
the exhaust manifold. When the exhaust pressure is above
atmospheric pressure, the reed valves prevent secondary air
from being sent back t o the air cleaner.

EF & EC-16
E.C.C.S. DESCRIPTION
Components (Cont'd)
EXHAUST GAS SENSOR (Titania type) IVG30ETI
The exhaust gas sensor, which is placed in the exhaust tube,
~ %nwr element (Titania)
monitors the amount of oxygen in the exhaust gas.
Lead terminals This sensor is made of ceramic titania which electric resistance
drastically changes a t the ideal air-fuel ratio.
The E.C.U. supplies the sensor with approximately 1V and takes
an output voltage of the sensor depending on i t s resistance. In
order t o activate the sensor element, it is equipped with a heater.

:I I-. fq,"
-
C
I

-
-
c

-r
*
.-
Le
Rich-
~~ SEF716D

ideal ratio + L~~~ RT: Resistanceof titania Rich C Ideal ratio+ Lean
I

Mixture ratio Rc: Comparative the E.C.U.)
[equipped i n resistance Mixture ratio
SE FZBSD

I EXHAUST GAS SENSOR (Zirconia Wpe) [VG30El
~~ ~

The exhaust gas sensor, which is placed into the exhaust mani-
fold, monitors the amount of oxygen in the exhaust gas.
The sensor has a closed-end tube made of ceramic zirconia. The
outer surface of the tube is exposed t o exhaust gas, and the inner
surface t o atmosphere. The zirconia of the tube compares the
Holder oxygen density of exhaust gas with that of atmosphere, and
generates electricity. In order t o improve generating power of
the zirconia, i t s tube is coated with platinum. The voltage is
SEF336A
approximately 1V in a richer condition of the mixture ratio
than the ideal air-fuel ratio, while approximately OV i n leaner
I conditions. The radical change from 1V t o OV occurs a t around
the ideal mixture ratio. In this way, the exhaust gas sensor
detects the amount of oxygen in the exhaust gas and sends the
signal of approximately 1V or OV t o the E.C.U.

Mixture ratio SEF288D

I I POWER TRANSISTOR AND IGNITION COIL
The ignition signal from the E.C.U. is amplified by the power
transistor, which turns the ignition coil primary circuit on and
off, inducing the proper high voltage in the secondary circuit.

EF & EC-17
E.C.C.S. DESCRIPTION
Components (Cont'd)
VEHICLE SPEED SENSOR
The vehicle speed Sensor provides a vehicle speed signal t o the
E.C.U.
Needle type spaadometer models
The speed Sensor consists of a reed switch, which is installed in

0 ;
Field plate
'%

Field plate
', Magnetic
line
the speed meter unit and transforms vehicle speed into a pulse
signal.

Digital type speedometer models
The speed sensor consists of an L.E.D., photo diode, shutter and
wave forming circuit. Its principle is the same as that of the
crank angle sensor.
Oil seal

0
To speedometer cable SEFeBOB

1
TYPE B A.I.V. CONTROL SOLENOID VALVE (TYPE B)
The A.I.V. control solenoid valve cuts intake manifold vacuum
signal for A.I.V. control. The solenoid valve actuates in response
t o the ON/OFF signal from the E.C.U. When the solenoid is off,
the vacuum signal from the intake manifold is cut. As the control
unit outputs an ON signal, the coil pulls the plunger downward,
and feeds the vacuum signal t o the A.I.V. control valve.

E.G.R. CONTROL SOLENOID VALVE (TYPE A)
SEFBlZE The E.G.R. syStem is controlled only by the E.C.U. A t both low
- and high speed revolution of engine, the solenoid valve turns on
TYPE A
TPlunger I

1
and accordingly the E.G.R. valve cuts the exhaust as leading
t o the intake manifold.

P.R. (PRESSURE REGULATOR) CONTROL SOLENOID
VALVE (VG30E: TYPE A, VG30ET: TYPE B)
The solenoid valve actuates in response t o the ON/OFF signal
from the E.C.U. When it is off, a vacuum signal from the intake
manifold is fed into the pressure regulator. As the control unit
SEF613E outputs an ON signal, the coil pulls the plunger downward, and
cuts the vacuum signal.

SAFETY RELAY
Safety relay, which is located behind the right side of hoodledge,
prevents any damage t o the E.C.U. and injectors when battery
terminals are connected in reverse.

EF & EC-18
E.C.C.S. DESCRIPTION
Components (Cont'd)
EXHAUST GAS TEMPERATURE SENSOR
[Carifornia model]
The exhaust gas temperature sensor is located near E.G.R. valve,
detects exhaust gas temperature and emits signals to the E.C.U.
This part employs a thermistor which is sensitive to changes in
temperature. The electric resistance of a thermistor decreases in
response to a temperature rise.

SEF072G

Fuel Injection Control
Engine speed and piston position
Crank angle sensor

Air flow meter
7 Amount of intake air
1
Engine temperature
b

Density of oxygen in exhaust gas
Exhaust gas sensor

Throttle valve idle position
' E.C.C.S.

NeutraI/lnhibitorrvvItch(VG30;;;] Gear position
control
unit
Injector
1
I I

Vehicle speed
b

Start signal
b

Fuel temperature
+
Battery voltage

EF & EC-19
E.C.C.S. DESCRIPTION
Fuel Injection Control (Cont'd)
The E.C.U. calculates the basic injection pulse width by process-
Rich ing signals from crank angle sensor and air flow meter. Receiving
A signals from each sensor which detects various engine conditions,
the E.C.U. adds various enrichments, which are pre-programmed
in the control unit, t o the basic injection amount. Thus, the
optimum amount o f fuel i s injected through the injectors.
1) Fuel enrichment
In each of the following conditions, fuel is enriched.
enrichment
During warm-up
When starting
enrichment After idle
With heavy load
When cylinder head temperature is high.
The enrichment rate for "when accelerating" and "with heavy
load" are pre-programmed for engine speed and basic injection
pulse width.
cylinder head temperature

SEF4860

2) Mixture ratio feedback control
I CLOSEOLOOP
CONTROL
'E.C.C.Sj
l f d I The mixture ratio feedback system is designed t o control

n
the mixture ratio precisely t o the stoichiometric point so
Feedback signal
that the three-way catalyst can minimize CO, HC and NOx
A emissions simultaneously. This system uses an exhaust gas
injector
sensor located in the exhaust manifold to give an indication
of whether the air-fuel ratio is richer or leaner than the
I injection
I stoichiometric point. The control unit adjusts the injection
pulse width according to the sensor voltage so the mixture
ratio will be within the narrow window around thestoichio-
metric air fuel ratio.
However, this system will open under the following con-
ditions:
When starting.
When engine and exhaust gas sensor is cold.
When driving a t high speeds or under heavy load.
A t idle
When exhaust gas sensor monitors a too lean condition for
more than 10 seconds.
When fuel shut-off is in operation.
When exhaust gas sensor is malfunctioning.
When pressure regulator control system is in operation.

EF & EC-20
Group injection 3) Injection timing
Two types of fuel injection systems are used - simultaneous
No. 1 cylinder
No. Znyd-l
n
tc
u injection and group injection. In the former, fuel is injected
into all six cylinders simultaneously twice each engine cycle.
No. n
3r.
iy
d
-cl In other words, pulse signals of the same width are simul-
NO. d
4nl
er
ic
-y
taneously transmitted from the E.C.U. t o the six injectors
No. 5 c y l i n d e r b
No. 6 c y l i n d e r b two times for each engine cycle.
C 1 engine c y c l e 4 In the group injection system, six injectors are divided into
two groups - No. 1, No. 2, No. 3 and No. 4, No. 5, No. 6.
And fuel is injected into each group separately once each
e Simultaneous iniection
engine cycle.
No. cylinder n n n When any of the following conditions are met, fuel injection
shifts t o simultaneous injection from group injection.
No. znl
d
-c
e
iy
r
e
d
-c
No. 3nliy
r Engine speed is more than 3,000 rpm.
No.4cy1inderu Cylinder head temperature is below 60

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