Land Rover Fuel Injection System Manual

							
LAND ROVER 
 
Mounting ECU and main + fuel relays
A metal structure was constructed from sections of narrow gauge steel an\
d angle iron to form a 
base in which the injection control box could tightly sit. This was scre\
wed to mounting positions in 
the battery box under the passenger seat. The 14CUX frame clears the pos\
itive terminal of the 
battery by roughly 2 inches. Both main and fuel relays are mounted to th\
e box frame using thin 
strip aluminium. 
 
Fitting the wiring loom
The fitting process took just under a day to complete. The wiring requir\
ed some clamps and 
supports to be fabricated, and copper ties were used in the exposed area\
s under the chassis. With 
the 14CUX mounted under the passenger seat, the loom wiring exits the ba\
ttery box via a 
grommet lined large diameter hole. It then passes over the top of the ge\
ar box and on to the 
driver side of the vehicle where it turns sharp left to head towards the\
 engine. As it passes under 
the chassis before the firewall it is clamped via two copper ties until \
it reaches the firewall. At that 
point it heads directly upwards while being tied tightly to the wall (i\
n order to avoid the exhaust 
components). At the top of the firewall at roughly the same height as t\
he rear of the drivers side 
engine rocker cover, the loom splits into three sub parts. The first is \
the wiring used to drive the 
even bank of injectors and which runs straight down the plenum side. The\
 second is the even bank 
lambda sensor connector which hangs at that point with roughly 10 inches\
 of cable slack, and the 
third is the wiring used to pass over the transmission tunnel. 
 
That third section of the wiring extends for about 12” as one solid l\
oom as it passes over the 
transmission tunnel before itself splitting into two further sub parts. \
The first is the odd bank 
lambda sensor connector which again hangs at that point with roughly 10 \
inches of cable slack, 
and the second is the section of wiring used to drive the odd bank of in\
jectors. 
 
The arrangement of the cabling round the injectors and various sensors i\
s cable tied where 
appropriate.
 
 
 
 
Fitting the 14CUX diagnostic reader
The 14CUX does have a limited diagnostic capability. It is capable of dr\
iving a two digit display in 
order to announce fault codes. If the display is empty – the system i\
s running correctly. 
 
The 14CUX system on the donor vehicle did not include a fault display an\
d unfortunately, Land 
Rover no longer manufacture these units. However, a company called Steve\
 Heath Engineering Ltd 
does manufacture very good quality readers which saved the time required\
 to analyse and 
interface to the serial communications link from the 14CUX control unit.\
 
 
The Heath Engineering display is shipped with a cable employing an inlin\
e connector which breaks 
out to four push fit pins designed to insert directly into the standard \
14CUX diagnostics plug as 
follows:-
 
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LAND ROVER 
Figure 61 – Wiring the diagnostic display into the loom plug
 
 
Using the diagnostic reader
First the reader must be used in “connect” mode by pushing the swi\
tch away from you. Turn on the 
ignition, at which point the status LED (the DP on the seven segment di\
splay) will illuminate. If any 
error code is stored by the 14CUX it will be displayed now.
 
You can easily simulate a code 15 error by disconnecting the fuel temper\
ature sensor. 
 
Clearing error codes can be done in two ways. The ECU can be powered off\
 by disconnecting the 
main harness connector. This will reset the ECU and clear all fault info\
rmation. A second method 
will clear the current fault and then display the next one (when there \
are multiple faults). The 
procedure is repeated until no more codes are displayed. The procedure i\
s as follows:-
 1.  Disable the immobiliser
2.  Switch the ignition on
3.  Disconnect the fault code reader by throwing the switch on the box. \
The status LED and any  code will go out. Wait 5 seconds, and then reconnect the box by throwing\
 the switch into the 
connect position. 
4.  Switch the ignition off and wait for the main relay to drop out (a \
good 5-10 seconds). 
5.  Disable the immobiliser
6.  Switch the ignition on
7.  The display will either display the next fault code, OR will be blan\
k (when all fault codes have  been shown). Repeat steps 3 to 6 until all codes have been seen. 
 
If a fault causing a code isn’t rectified, then the code will continu\
e to be seen. On first sight it may 
seem that the code isn’t being cleared – whereas it actually is be\
ing cleared but the 14CUX is 
continuing to see and report the same fault code. 
 
It is also worth understanding that some codes can’t be cleared by an\
ything other than a full power 
down (removal of the main harness plug). 
 
 
Fuel cut off – inertia switch
The injection system relies on a constant fuel pressure feed rated at ap\
proximately 3 bar. In terms 
of open flow rate, that equates to 135 litres of fuel flowing per hour, \
or 2.25 litres per minute. The 
risk of an accident rupturing the fuel lines but leaving the fuel pump p\
owered represents an 
obvious threat. As a result Range Rovers were fitted with inertia switch\
es mounted inside the 
vehicle, on a solid part of the frame.  In the event of an accident exhi\
biting sufficient levels of 
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LAND ROVER 
stopping G force, the inertia switch activated and disconnected the fuel\
 pump. 
 
If the inertia switch false triggers, it is a simple matter to push in t\
he activation button in order to 
reset it. This switch is wired directly in line with the fuel pump. 
 
The target vehicle employs the same precaution using an inertia switch s\
pecified for the donor 
vehicle.  
 
A range rover inertia switch has been bolted to the B pillar directly be\
hind the front passenger seat 
back rest. It is mounted button up with its back surface parallel to the\
 side of the vehicle. It is 
wired in line with the supply feed to the fuel pump and interrupts that \
connection if a sufficiently 
violent impact occurs.
 
 
Appendix A – 14CUX Fault Codes
 Code Meaning Comments
02 Live +12v supply to ECU has 
been disconnected Normal code that appears whenever the ECU 
is first reconnected. Code 02 will clear when 
ignition is switched off, the main relay is 
allowed to release and the ignition is switched 
on again.
03 Stored data corrupted since last 
trip No useful information available. Test drive and 
try again
13 Air flow meter out of range Possible air leak or wiring fault
14 Coolant thermistor out of range Faulty sensor or wiring
15 Fuel thermistor out of range Faulty sensor or wiring
17 Throttle sensor out of range Sensor needs adjustment, is faulty, or has 
wiring fault. This can cause low speed misfires 
and can also prevent the system setting low 
idle speed. 
18 Throttle sensor output too high 
when air flow low Large air leak between throttle butterfly and A/
F meter or faulty throttle sensor or A/F meter
19 Throttle sensor output too low 
when air flow high Faulty A/F meter or throttle sensor
21 Tune resistor out of range Check tune resistor and wiring
23 Low fuel pressure Blocked fuel filter or faulty pump or pressure 
regulator. Valid for cat cars only
25 Misfire at full load Faulty plugs, leads, electronic ignition unit, 
distributor or coil, low fuel pressure or valve or 
head gasket leak. Valid for cat cars only. 
 
The lambda sensors have detected an 
emission fault which could be caused by 
almost anything in the ignition and injection 
system. 
 
If this is code 40 or 50 it will indicate which 
side of the engine the fault is (but be aware 
this can be misleading if the lambda sensors 
are faulty).
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26Very lean mixture Lean or misfire condition. Probable causes are 
a faulty low or out of range lambda sensor or 
an ignition fault causing a misfire. This code is 
generally only used on the jaguar 
implementation of the 14CUX and is generally 
not listed under the Range Rover fault codes. 
28 Air leak Check for air leaks in the following areas
l     Hose, air flow meter to plenum
l     PCV
l     Brake servo hose
l     Distributor advance/retard pipe
l     Injector seals
l     Any other joints and seals
29 Checksum error ECU has failed its internal self test. If 
detected, any other codes are unreliable. Try 
powering the ECU off. If the fault continues, 
then the ECU must be replaced. 
34 Fueling fault in nearside injector 
bank Injector or lambda sensor wiring fault, faulty 
injectors, air leak at injector seals or intake 
manifold, blocked injectors. Valid for cat cars 
only on cylinders 1,3,5 and 7
36 Fueling fault in offside injector 
bank Injector or lambda sensor wiring fault, faulty 
injectors, air leak at injector seals or intake 
manifold, blocked injectors. Valid for cat cars 
only for cylinders 2,4,6 and 8
40 Misfire on nearside bank Misfire has occurred on cylinders 1,3,5 and 7. 
Valid for cat cars only (see code 25 for more 
details and suggestions)
44 Nearside lambda sensor out of 
range Faulty or lead-poisoned lambda sensor. Valid 
for cat cars only. If codes 45 and 45 appear 
then the likely cause is the heater wiring for 
both lambda sensors. 
45 Offside lambda sensor out of 
range Faulty or lead-poisoned lambda sensor. Valid 
for cat cars only. If codes 45 and 45 appear 
then the likely cause is the heater wiring for 
both lambda sensors. 
48 Stepper motor (bypass air 
valve) fully open below 500RPM 
or fully closed above 750 RPM Sticking stepper motor valve, incorrect base 
idle speed adjustment, air leak on non cat 
cars, incorrect stepper motor adjustment, 
incorrect throttle butterfly adjustment, rough 
running (due to fuel, ignition or mechanical 
faults) and finally a faulty road speed 
transducer can cause this problem. 
 
Note that low fuel pressure can cause this 
problem especially if it causes the engine to 
stumble at idle or very low speed. 
50 Misfire on offside bank Misfire has occurred on cylinders 2,4,6 and 8. 
Valid for cat cars only (see code 25 for more 
details and suggestions)
58 ECU unable to distinguish 
between faults 23 and 28 Fault occurred for an insufficient time for ECU 
to correctly diagnose. 
59 Fuel thermistor our of range Fuel thermistor fault – but be aware that in 
some documentation code 59 is described as 
code 58. 
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LAND ROVER 
68Road speed sensor output too 
low at medium RPM and high air 
flow Possible sensor or wiring fault. Valid for cat 
cars only
88 Power up check Two interpretations for this. For non cat cars, 
the code is shown on power up but isn’t a 
code. For cat cars it is used to show that there 
is a purge valve fault with the evaporative 
emissions carbon canister system. 
 
 
Appendix B – Final notes, comments and links
 
l     Engine thermostat must be a 74 degrees C part with no joggle hole
 
l     Engine air filter is standard range rover 1992 part number RTC 4683
 
l     Bypass air valve is standard 1992 range rover part
 
l     Throttle potentiometer is standard 1992 range rover ETC 8495 part
 
l     As described above the PCV system connects to the plenum vacuum source v\
ia a 2mm 
drilled orifice. This is additional to the plastic PCV T piece supplied \
by land rover which has a 
3mm restriction orifice. 
 
l     14CUX workshop manual link: www.conehead.org/landrover/14cux_fuel_injection.pdf
 
 
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							;;^d;‘;r; 1987
FUEL INJECTION SYSTEM 119 1r
U.
w
Ui I““IRR1752EFUEL 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. Neutralswitch (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. Coolanttemperaturethermistor (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
BBlackGGreenRRedUBlue0
OrangeM’White
NBrownPPurpleYYellow
The last letter of a colour code denotes the tracer.
REVISED: JULY 88
SCrey
KPink
LGLight green
1 
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							l-l19 FUEL INJECTION SYSTEM1987 rot;;
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2REVISED: JULY 88 
						

							ggf;i 1987
FUEL INJECTION SYSTEM 119 1INTRODUCTION
The Electronic Fuel injection system provides a
reliable and efficient microprocessor controlled fuel
management system.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 ElectronicControl Unit (E.C.U.), the E.C.U. will then
determine the exact amount of fuel required at any
condition.The E.C.U. having received data from the sensors
produces pulses, the length of which will determinethe simultaneous open time of each bank of
injectors in turn, which will govern the amount of
fuel injected.DESCRIPTION
ELECTRONIC CONTROL UNIT-ECU
The Electronic Fuel Injection system is controlled bythe E.C.U. which is located under the front right
hand seat. The control unit is a microprocessor withintegrated circuits and components mounted on
printed circuit boards. The E.C.U. is connected to
the main harness by a 40 pin plug.INJECTORS
The eight fuel injectors are fitted between the
pressurized fuel rail and inlet manifold. Each injectorcomprises 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.ENGINE COOLANT TEMPERATURE THERMISTOR
(SENSOR)
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.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.BYPASS AIR VALVE (STEPPER MOTOR)
The bypass valve is screwed into a housing attachedto 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.LAMBDA SENSORS 
(0, SENSORS)
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 heatedby an electrical element to improve its response
time when the ignition is switched on.
ContinuedREVISED: APR. 87
3 
						

							FUEL INJECTION SYSTEM1987 rGv;;
FUEL PRESSURE REGULATORTHROlTLE POTENTIOMETERThe 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.
FUEL PUMPThe 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 SENSORThe 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.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,
thusrotating
thewiper
armwithin
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
changeinoutputvoltage (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
percentageandisindependent 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.
ROAD SPEED TRANSDUCERThe 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.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.
J
:.....
j
4REVISED: APR. 87 
						

							: ..
‘.’ :
., .’
.,
‘. ,‘,‘.‘. :::, ..i.’
FOE; 1987
FUEL INJECTION SYSTEM b ii\INERTIA SWITCH
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.
RELAYSThe 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.Uwhen 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.‘:.,.*aAir flow sensor.
Lambda sensor.
-Water temperature thermistor. (sensor)
Throttle potentiometer.
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.
..:
.‘.,.2: :_‘. ‘*. . .. .REVISED: JULY 88