Range-Rover-Manual-Fuel-Injection, Land Rover(2)
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;;^d;‘;r; 1987
FUEL INJECTION SYSTEM 119 1
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RR1752E
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FUEL INJECTION - Circuit Diagram
1. 40 way connector to Electronic Control Unit
(ECU).
2. Lambda sensor (left side - bank A).
3. Lambda sensor (right side - bank 8).
4. By-pass air valve (stepper motor) (fast idle).
5. Lambda sensor screened ground.
6. Fuse 18 - main fuse panel.
7. Inertia switch.
8. Fuel pump.
9. Ignition switch.
10. Speed transducer (road speed input).
7 1. Neutral
switch (automatic gearbox) (load
input).
12. Pick-up point-air conditioning circuit (load
input).
13. Battery.
14. Diagnostic plug.
15. In-line resistor.
16. Coil/-ve (engine RPM input).
17. Coolant
temperature
thermistor (sensor)
(input).
18. Fuel temperature thermistor (sensor) (input).
19. Throttle potentiometer.
20. Air flow sensor.
21. Fuel pump relay.
22. Main relay.
23. Injectors-l to 8.
24. Pick-up point E.F.I. warninasymbol (instrument
binnacle).
= = =
Denotes screened ground.
NOTE: Reference to left and right side is made when viewing vehicle from rear.
Cable colour code
B
Black
G
Green
R
Red
S
Crey
U
Blue
0
Orange
M’
White
K
Pink
N
Brown
P
Purple
Y
Yellow
LG
Light green
The last letter of a colour code denotes the tracer.
REVISED: JULY 88
1
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19 FUEL INJECTION SYSTEM
1987 rot;;
ECU AND RELAY8
1
L
FWL RCOULATOR
41 RCA1 OF ENOINE
UNDER RIGHT FRONTOEAT
F
:lJEL FILTER ON CHAlllll#
FUEL WYP
111 FUEL TANA
a lNJcc10ns
FOR ENONE
ROAO OFEED WUt
TIIANOOUCER
I
ON CNAIOW
FUEL TEYFEIIATURE
EN10R
liNOiNE FULL RAIL
A-
A1111 IV’cA1I VALVE
REAR
OF ENOWE
BAV
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P
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COOLANT tEYPERATU(IE
LNIOR FRONT OF ENOM
TWROTTLE FOTENTIOYETE
FRONT OF
THROTTLE VALVE
HOT WIG ARFLOW
8ENaoR FRONT LEFT
EIE OF LNONE
AV
lONRlON COL
LEFT IDE OF
EN[IE
AV
RR2178E
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REVISED: JULY 88
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ggf;i 1987
FUEL INJECTION SYSTEM 119 1
INTRODUCTION
ENGINE COOLANT TEMPERATURE THERMISTOR
(SENSOR)
The Electronic Fuel injection system provides a
reliable and efficient microprocessor controlled fuel
management system.
The coolant thermistor (sensor) is located by the
front left hand branch of the intake manifold. The
thermistor provides engine coolant information to
the E.C.U. The E.C.U. on receiving the signal from
the thermistor will lengthen slightly the time that
the injectors are open, and reducing this time as
the engine reaches normal operating temperature.
The function of the system is to supply the exact
amount of fuel directly into the inlet manifold
according to the prevailing engine operating
conditions.
To monitor these conditions, various sensors are
fitted to the engine to measure engine parameters.
Data from the sensors is received by the Electronic
Control Unit (E.C.U.), the E.C.U. will then
determine the exact amount of fuel required at any
condition.
FUEL TEMPERATURE THERMISTOR (SENSOR)
The fuel temperature thermistor (sensor) is located
in the fuel rail forward of the ram housing. The
thermistor sends fuel temperature data to the
E.C.U, the E.C.U on receiving the data will adjust
the injector open time accordingly to produce
good hot starting in high ambient temperatures.
The E.C.U. having received data from the sensors
produces pulses, the length of which will determine
the simultaneous open time of each bank of
injectors in turn, which will govern the amount of
fuel injected.
BYPASS AIR VALVE (STEPPER MOTOR)
The bypass valve is screwed into a housing attached
to the rear of the plenum chamber, between the
plenum chamber and bulkhead. The bypass valve
has two windings which enable the motor to be
energised in both directions thus opening or
closing the air valve as required by the E.C.U.
The bypass valve will open and allow extra air into
the plenum chamber to maintain engine idle speed
when the engine is under increased (Electrical and
Mechanical) loads.
The bypass valve will control engine idle speed
when the vehicle is stationary.
DESCRIPTION
ELECTRONIC CONTROL UNIT-ECU
The Electronic Fuel Injection system is controlled by
the E.C.U. which is located under the front right
hand seat. The control unit is a microprocessor with
integrated circuits and components mounted on
printed circuit boards. The E.C.U. is connected to
the main harness by a 40 pin plug.
INJECTORS
LAMBDA SENSORS (0, SENSORS)
The eight fuel injectors are fitted between the
pressurized fuel rail and inlet manifold. Each injector
comprises a solenoid operated needle valve with a
movable plunger rigidly attached to the nozzle
valve. When the solenoid is energized the plunger
is attracted off its seat and allows pressurized fuel
into the intake manifold.
The two Lambda sensors are located fonvard of the
catalysts mounted in the exhaust downpipes.
The sensors monitor the oxygen content of the
exhaust gases and provide feedback information of
the air/fuel ratio to the E.C.U. Each sensor is heated
by an electrical element to improve its response
time when the ignition is switched on.
Continued
REVISED: APR. 87
3
FUEL INJECTION SYSTEM
1987 rGv;;
FUEL PRESSURE REGULATOR
THROlTLE POTENTIOMETER
The fuel pressure regulator is mounted in the fuel
rail
at the rear of the plenum chamber. The
regulator is a mechanical device controlled by
plenum chamber vacuum, it ensures that fuel rail
pressure is maintained at a constant pressure
difference of 2.5 bar above that of the manifold.
When pressure exceeds the regulator setting excess
fuel is returned to the fuel tank.
The throttle potentiometer is mounted on the side
of the plenum chamber inlet neck and is directly
coupled to the throttle valve shaft.
The potentiometer is a resistive device supplied
with a voltage from the E.C.U. Movement of the
throttle pedal causes the throttle valve to open,
thus rotating the wiper arm within the
potentiometer which in turn varies the resistance in
proportion to the valve position. The E.C.U.
lengthens the injector open time when it detects a
change in output voltage (rising) from the
potentiometer.
In addition the E.C.U. will weaken the mixture
when it detects the potentiometer output voltage is
decreasing under deceleration and will shorten the
length of time the injectors are open.
When the throttle is fully open, the E.C.U. will
detect the corresponding throttle potentiometer
voltage and will apply full load enrichment. This is a
fixed
percentage and is
independent of
temperature. Full load enrichment is also achieved
by adjusting the length of the injector open time.
When the throttle is closed, overrun fuel cut off or
idle speed control may be facilitated dependant on
other inputs to the E.C.U.
FUEL PUMP
The electric fuel pump is located in the fuel tank,
and is a self priming ‘wet’ pump, the motor is
immersed in the fuel within the tank.
AIR FLOW SENSOR
The hot-wire air flow sensor is mounted on a
bracket attached to the left hand valance, rigidly
connected to the air cleaner and by hose to the
plenum chamber inlet neck.
The air flow sensor consists of a cast alloy body
through which air flows. A proportion of this air
flows through a bypass in which two wire elements
are situated: one is a sensing wire and the other is
a compensating wire. Under the control of an
electronic module which is mounted on the air flow
sensor body, a small current is passed through the
sensing wire to produce a heating effect. The
compensating wire is also connected to the module
but is not heated, but reacts to the temperature of
the air taken in, as engine intake air passes over the
wires a cooling effect takes place.
ROAD SPEED TRANSDUCER
The road speed transducer is fitted between the
upper and lower speedometer cables. It is mounted
on a bracket located on the left hand chassis side
member adjacent to the rear engine mounting. The
transducer provides road speed data to the ECU.
The ECU in turn detects vehicle movement from
the road speed input and ensures that idle speed
control mode is disengaged. Should the speed
transducer fail in service the ECU idle speed control
would become erratic.
The electronic module monitors the reaction of the
wires in proportion to the air stream and provides
output signals in proportion to the air mass flow
rate which are compatible with the requirements of
the E.C.U.
J
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4
REVISED: APR. 87
FOE; 1987
FUEL INJECTION SYSTEM b ii\
INERTIA SWITCH
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The inertia switch is a mechanically operated switch
located under the left hand front seat attached to
the seat base rear cross-member.
The switch is normally closed and is in the ignition
feed (fuse to fuel pump). In the event of a sudden
impact the switch opens, and disconnects the
electrical feed to the fuel pump. The switch is reset
by pressing down the button.
RELAYS
The two electronic fuel injection relays are located
under the front right hand seat mounted forward of
the E.C.U. The main relay is energized via the E.C.U
when the ignition is switched on and supplies
current to the fuel injection system. The fuel pump
relay is energized by the E.C.U. which in turn
operates the fuel pump to pressurize the fuel
system.
E.F.I. WARNING SYMBOL (Instrument binnacle)
An E.F.I. warning symbol incorporated into the
instrument binnacle will illuminate when the E.C.U.
detects that it cannot maintain correct air/fuel ratio
due to a fault in one of the follolOring fuel injection
system components.
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Air flow sensor.
Lambda sensor.
-
Water temperature thermistor. (sensor)
Throttle potentiometer.
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The symbol will illuminate on initial turn of the
ignition key as part of the bulb check feature, and
will go out after a few seconds.
If the symbol illuminates when the engine is idling
or the vehicle is being driven it indicates a failure of
one of the four functions, the vehicle should be
driven with care, and the cause rectified, refer to
test procedure for the particular functions. Should
one of the functions fail, the vehicle can still be
driven due to a limp home feature incorporated
into the fuel injection system.
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REVISED: JULY 88
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