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

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

E. C. C. S. DESCRIPTION
Deceleration from @
Deceleration from @
Deceleration from 0 or @
Fuel Injection
2) Fuel shut-off
Fuel shut-off is accomplished under the follow-
ing conditions.
a During deceleration
@ and @ 62
0 (E9
- -
- -.. . . . ._ '. .
VG30ET (MITI
VG30E
_-- VGXIET IA/Tl
-20 0 20 40 60 SO 100
(-41 1321 (681 11041 (1401 (1761 12121
Cvlinder head IemPerature "C 1°F)
SEF638B
b High engine speed
When engine speed is more than 6,500 rpm,
fuel
is shut-off for safety reasons
High vehicle speed
(VG30ET engine only)
When vehicle speed
is more than 220 km/h
(137 MPH), fuel is shut-off for safety reasons
c
mtrol (Cont'd)
3) Mixture ratio feedback control
Mixture ratio feedback system is designed to
control the mixture ratio precisely to the
*stoichiometric point
so that the three-way
!catalyst can minimize
CO, HC and NOx emis-
';ions simultaneously This system
uses exhaust
gas senwr located in the exhaust manifold to
give an indication of whether the air-fuel ratio
is richer or leaner than the 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 the stoichiometric
air fuel
ratio
eontroi
Injector
0
Combustm
Engme
However, this system will open under the
following conditions
When starting engine.
When engine and exhaust
gas sensor is cold
When driving
at high speeds or under heavy
load.
At idle
When exhaust
gas sensor monitors a too lean
condition for more than
10 seconds.
When fuel shut-off
is in omration
EF & EC-21

E.C.C.S. DESCRIPTION
-Fuel injection Control (Cont'd)-
4) Simultaneous injection and group injection
On the VG30ET engines, two types of fuel
injection systems
are used - simultaneous
injection and group injection. In the former,
fuel is injected into all six cylinders simulta-
neously twice each engine cycle
In other words, pulse signals
of the same width
are simultaneously transmitted from the
E C.C.S. control unit to the six injectors two
times for each engine cycle
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 engine
cycle
Group injection
NO 1 cylmder u
No 5 cylinder n
No 6cylinder _n
No 1 cylinder u
NO 2 cylinder -
u
u
u
u
NO 2 cylinder-
No 3 cylinder -
No 4 cylmdern
L- 1 engine cvcle4
. Slrnultaneous ln,ect,On
No 3 cylinder
No 4 cylinder
No 5 cylinder
No 6 cylinder
I 1 engm cycle I
SEF640B
When any of the following conditions are met, fuel
injection shifts to simultaneous injection from
group injection.
Engine speed is more than 3,000 rpm
Injection pulse duration is more than 6.5ms
Cylinder head temperature IS below 60°C
(1 40" F)
EF & EC-22