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

PRECAUTIONS
Always use 12 volt batteries as * Do not disassemble E C C S When installing large capacity wire-
Do not attempt to disconnect Do not turn diagnosis mode sure to obsetve the following as it power source
battery cables while engine
IS
control unit
selector less equipment or a vehicle phone, be
may adversely affect electronic con-

operating
Do not apply battery power
directly to injectors
Do not remove the fuel tem-
perature sensor from
the T

pressure regulator
Replace as an assembly
trol systems depending on its installa-
tion location
1) Keep the antenna as far as possible
away from the electronic control
units
2) Also keep the antenna feeder line
more than
20 cm (7 9 in) away from
the harness of electronic controls
Do not let them run parallel for a
long distance
3) Adjust the antenna and feeder line so
that the standing-wave ratio can be
keot smaller
J
Handle air flow meter care-
fully to avoid damage * Do not disassemble auxiliary
Do not disassemble air flow air control valve (VG30ET
meter engine)
Do not clean air flow meter
with any type of detergent
0 Even a slight leak in the air in- /
&&%$$?&
take system can cause serious
problems
Do not depress accelerator Do not shock or jar the crank
angle sensor
Immediately after starting, do
pedal when starting
not rev
up engine unneces-
sarily
Do not rev up engine just prioi
to shutdown
Do not operate fuel pump when
there is no fuel in lines Do not use anti-freeze agents in fuel
0 Do not reuse fuel hose clamps
0 Tighten fuel hose clamps sufficiently
Securely connect E C C S harness
connectors
A poor connection can cause an ex-
tremely
high (surge) voltage to
develop in coil and condenser, thus
resulting in damage to IC circuit
Keep
E C C S harness at least 10 cm
(3 9 in) away from adjacent
harnesses, to prevent an
E C C S
system malfunction due to reception
of external noise, degraded operation
of
IC circuit. etc
Keep E C C S parts and harnesses
Before removing parts, turn off igni-
tion switch and then disconnect
battery ground cable dry
SEF6008
EF & EC-2

E. C. C.S. CHART
VG30ET Engine (With turbocharger)
Air flow meter c
Cylinder head temperature sensor b
b
Ignition switch b
Throttle valve switch I b
b
Park/Neutral switch
Air conditioner switch I
b
E C C.S
control
unit
b
Injectors Fuel injection &
mixture ratio control
--I
Ignition timing control Power transistor
-dI Auxiliary air control
(A A
C ) valve Idle speed control
I YL
E G R control E G R control solenoid valve
Fuel pump control Fuel pump
Inspection lamps ixhaust gas sensor
nonitor
& self diagnosis I
EF & EC-7

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
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

ELECTRONIC CONTROL SYSTEM INSPECTION
Check harness ~~
@ Auxiliary
air control (A A.C.) valve or idleup solenoid valve
Repair harness
Disconnect E C C S 20-pin connector, and check
voltage between terminal @and ground when igni-
tion switch
is turned to ON
LEU Battery voltage
I SEF695B
NG I
Replace E F I relay the fuel pump relay. check E F I relay I
OK I
Check A A C valve or idle-up solenoid valve
Replace A A C valve or idle-up
solenoid valve
I
EF & EC-54