Triumph TR7 User manual

TR7
TRB
ROVER 3500
III
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TRIUMPH FUEL INJECTION _
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NORTH AMERICAN SPECIFICATION -1980 MODELYEAR
EMISSION AND EVAPORATIVE LOSS CONTROL EQUIPMENT
AND
MAINTENANCE INFORMATION
.JAGUAR ROVER TRIUMPH INC
6OOWlLLOWTREE ROAD. lEONIA
NEWJERSEY07605
Publication Part No. AKM 8072/80 U.S.A.

THIS HANDBDDK IS TD BE USED IN CONJUNCTiON
WITH THE DRIVERS/OWNERS HANDBOOK FOR
COMPLETE
VEHICLE OPERATION.
INTRODUCTION
VehIcles manufactured to the North American specification satIsfy the requirements of the vanous Federal. California State and
other Regulations.
This publication describes the function
of the emission and evaporative loss control systems. together with instructions for the
maintenance required
to keep the vehicle in good running order
The Manufacturers reserve the right to vary their specifications WIth or Without nollce, and al such times and In such manner as
they think fit. Major as well as mmor changes may be involved in accordance With the Manufacturer's policy of constant product
Improvement
The replacement or repair of the emission control devices
and systems may be performed by any automotive repair
establishment or individual using any automotive part which
has been certified by
the part manufacturer.
2

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
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Fig. 2Rover 3500 Fuel Instructions
3
Fuel
CAUTION: It is essential that unleaded fuels are used in
these vehicles otherwise serious damage can be caused to
the catalytic converter and the oxygen sensor(s) fitted in the
exhaust system,
Emission Control Systems -Servicing
The importance of servicing at the correCllntervals cannot be
over-stressed, as improvements in design and manufacturing
techniques count for nothing if the servicing standards are
not upheld.
Routine servicing. carried
out at the mileage intervals quoted
in the 'Maintenance Summary', helps
to prevent deterioration
of the systems
It is recommended that all servicing. particularly of the
emission and evaporative loss control systems, be carried
out
by skilled and competent personnel.
After any attention to these systems, or after achange to the
engine settings, it is essential that the exhaust emission
levels are checked using proper equipment.
EMISSION AND EVAPORATIVE LOSS
CONTROL SYSTEMS
All Rover-Triumph models entering the North American
markets incorporate efficient emission control systems,
These systems enable the vehicles to conform with all
current Regulations governing the emission of hydrocarbons,
carbon monoxide. nitric oxide and the emission of fuel,
by
evaporation, from the fuel delivery system.

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
4
Fig. 3 Main electronic fuel injection system compommu
Electronic Fuel Injection
In convenltonal carburener luel system engines. fuel mixes
with the aIr stream entering the engine combustIOn
chambers by means of fixed and/or vanable Jets In the
carburetter(sJ Despite advances
In desIgn. the carburetter IS
not atotally efficient means 01 dispensing fuel lor all the
many and varIed engine operating conditions. parllcularly
when stringent e::o:haust emiSSion levels must be met For this
reason an electrOniC fuel Injection system IS fitted to these
models and carburetters are nOt used.
An electrOniC fuel Injection system comprises. as the name
suggests. 01 two parts:-
Afuel injection system and an electronic control for the fuel
injection system.
Key to Fig. 3
(AI Fuel Injector
(8) Fuel pressure regulator
(e) Extra AIr Valve
(D) Fuel
pump
(E) Air Flow Meter
IF) Electronic control Unit
Should it be necessary to remove or exchange an injector, a
new sealing ring must be fined.

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Fuel Injection System Components
Fuel is drawn from atank al the rear of the vehicle and
pressurised to approximately 2,5 kgf/cm2(36 Ibl/in2) by an
electric fuel pump located benea~h the car floor. The fuel
pump will only operate when the ignition and/or the starter
motor circuits are energised, From this pump fuel passes
through fuel filters located in the engine compartment (Rover
3500) or beneath the car floor (TR models} to apressure
regulator, the spring chamber of which is connected to the
engine intake manifold. As aresult, the difference between
the intake manifold pressure and the fuel pressure is held
constant, excess fuel being returned to the fuel tank via an
anti-surge pot
Afuel rail links the pressure regulator with the fuel injectors,
one injector being fitted into each inlet manifold spur. The
injectors may
be either ·open' or 'closed· and are solenoid
operated, The
injector solenoids are energised through a
relay actuated by the ignition circuit and are pulsed to ·open·
by the electronic control unit (LeU.) completing the circuit
to 'ground:' When 'open'the injectors spray fuel into the Inlet
manifold to be drawn into the engine cylinders at the next
induction stroke of the working cycle.
Therefore there needs to
be no fixed relationship between the
injector timing and the engine ignition or valve timing.
The injectors are programmed to ·open' in banks of four.
in
unison, twice per engine operating cycle (two revolutions).
On eight cylinder engines the two banks of four injectors
operate alternately, The time that the injectors are ·open'
governs the amount of fuel supplied to the engine and this
open' time is computed by the electronic control unit from
the input it receives from various sensors
Fig,4 TR7 Fuel injection system components
Key to Fig, 4
(1) Cold start injector
(2) Injectors
(3) Fuel rail
(4) Cold start injector -fuel feed pipe
(5) Fuel pressure regulator
(6) Return line to fuel tank
(7) Pipe to plenum chamber
(8) Thermo time switch 5

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Fig. 5 TR8 Fuel injection system (:omponents
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(1) Fuel feed Plpe from tank
(3) Fuel rail
(6) Manifold depreSSion to pressure regulator Pipe
(8) Injectors
(9) Cold start injector fuel feed pipS
(10) Cold starl Injector
6

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Fig. 6Rover 3600 Fuel injection system componenta
(1) Fuel feed pipe from tank
(2) Fuel fllter/s)
(3) Fuel rail
(4) Pressure regulator
(5) Fuel inlet to pressure regulator
(6)
Manifold depression to pressure regulator pipe
(7) Excess fuel return to tank from pressure regulator
(8) Injectors
(9) Cold start injector fuel feed pipe
(10) Cold start injector 7

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
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Electric Fuel Pump Operation
The fuel pump IS energIsed, .ndependant of the electrOniC
control Unit, from an output terminal on the combined relay
The combined relay IS the component that prOVIdes an
interface between the main vehIcle electrical harness and
those ,tems that are spec,f,cally related to the electrOniC fuel
injectIOn system. An inertia SWItch .s Included In the CirCUit to
Isolate the fuel pump and prevent
II from operattng In the
event of an Impact type
accident The CIrCUit is also routed
through the electrOniC control system Air Flow Meter where a
simple contact
SWitch ensures that the fuel pump cannot
operate when
no air IS flOWing mto the engine i,e the engine
is no! running. ThiS contact SWitch IS by-passed when the
starter motor
CirCUit IS energised
Once the engine
IS runnmg a ClrCUlt from the Ignl\lon SWitch
passes througharelay ,aground,viatheelectroniC control Unit
on TAl models When energised th.s relay permIts a CIrCUIt
to be made to the AIr Flow Meter contact SWItch ProvIding
the contact switch
IS closed a CirCUit IS completed through a
second relay, again
to ground. When energised thiS second
relay completes the
CirCUIt to operate the fuel pump
Under engme starting conditions the Air Flow Meter contact
switch would normally Isolate the fuel
pump as no air IS
flowing through the engine. To overcome thiS an Input IS
taken direct from the starter motor CirCUit to energise the
second relay and thus permit the fuel pump
to operate during
the engine starting operation
8Fig. 8Circuit
principles of fuel pump operation

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Cold Starting Fuel Injection System Components
To assist cold starting, aseparate cold start injector sprays a
fine jet of fuel against the air stream entering the plenum
chamber before fuel
is added to il by the main inJeclors. The
cold start injector is energised from the engine starter motor
circuit and has
In series with it athermotime switch This
switch
is dual activated by the engine coolant temperature
(heat) and aheater coil around abi-metal strip (time), the coil
being again energised from the starter motor
CIrCUit. The
purpose of the
thermotime switch is to ensure that the cold
start Injector will not be energised when the engine is at
normal operating temperature or should the starter motor be
used for prolonged periods when the engine is below normal
operating termperature. Thus the switch prevents extra fuel
being supplied
to the engine when it is not reqUired. The
switch will Isolate the cold start injector after approximately 8
to 12 seconds at
-20°C (_4°F) decreasing this lime as the
engine approaches its normal operating temperature,
Although the
cold start injector and thermotlme sWitch
operate independantly
of the electronic control unit, an Input
to the E.C U. is taken from the starter motor CIrCUlI. This input
causes the
E.C.U to slightly lengthen the time that the main
injectors are ·open· thus allOWing more fuel to be supplied to
the engine whenever the starter motor
IS operated, This takes
place irrespective
of the mlormation supplied to the E.C.U by
the other sensors or any operation
01 the cold start Injector
Maintenance of Fuel Injection System Components
Apart from attention to the fuel filters alter 80.000 km
(50 000 milesL the, remaining components of the fuel
injection system reqUire no routme maintenance.
2157
Fig. 9Cold starting injector
2158
Fig. 11 Thermotime switch
9

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
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diegram for main and cold start injectors -TR7

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
111 EJII!OT I" R
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Fig.12 Wiring diagram for main and cold start injectors -Rover 3500
(The function of the power resistors 1$ to ensure that the correct current passes through the injector solenoidsl
11

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Electronic Control of the Fuel Injection System
At the heart of the electronic control system is the Electronic
Control Unit (E.C.U.) which
is abox approximately 23 x 18 x
5ems (9 x7x2Inches) located beneath a plate on the Iront
passenger footwell (Rover 3500) or under the glove box (TR
models), The E.C.U. receives input signals from various
sensors and computes from these an output signal to the fuel
injector solenoid circuits. When activated the solenoids
'open' the injectors to spray fuel into the engine inlet
manifold, the injectors remaining 'open' for between 1.5 and
10 milliseconds depending on engine running conditions.
The electronic control unit
is sealed, it requires no
maintenance and should
not be opened or tampered with.
Engine Speed
One of the first inputs required by the EG.U. is that of engine
speed and this input
is very simply obtained by taking a
tapping from the ignition coil
low tension circuit output
(negative terminal), Thus the ignition
low tenSion circuit
pulses are passed to the
E.C,U. to be computed into an
engine speed input.
Air Flow Meter
In addition to fuel. the most important input to the engine is
air and the ratio of air to fuel affects both the performance of
the engine and the emission levels of the exhaust gases,
Electronically controlled fuel injection systems
can 'measure'
the air used
by the engine In one of two ways. by air pressure
or
by air flow. The air flow alternative IS used on these
models.
12 Fig.
13 Electronic control unit
Continued

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
To measure the air flow Into the engine an Air Flow Meter is
fitted
In the engine compartment between the air cleaner and
a
plenum chamber above the engine. The plenum chamber
acts
as a collecting bOil: for the mgolng air and helps to
smooth out any rapId fluctuations in air flow that might upset
the Air Flow Meter signals.
The AIr Flow Meter Iiself IS basically ashort tube In which
there is apivoted measUring flap that IS moved by air flowing
past It Into the engine To reduce excessive fluttering of this
flap, such as would be caused by sudden changes or pulses
in the air flow. acompensating flap IS fllted as part of the
same casting as the measuring
Ilap_ The position of the
measunng flap IS controlled by the alf drawn into the engme
and the action of acoil return spring The mass of air drawn
Into the engine at any time IS Indlcatrve of the engine load
and aSIgnal. proportional
to the flap position. is passed to
the EC.U
However. the air mass IS related to air denSItY which In turn IS
dependant upon aIr temperature Therefore an AIr
Temperature Sensor IS Incorporated Into the Air Flow Meter
and this sends aseparate electrical Signal to the EC U
Due to the action of the COil return spring. the Air Flow Meter
measuring flap IS almost closed when the engine IS Idling
and an Idle aIr by-pass channel IS provIded to assIst the
engine to breathe at this low speed Air passing through the
by-pass channel
IS not registered by the Air Flow Meter
measuring flap
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Fig.14 Air flow m.t ....
13

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
14
Fig. 15 Contact type throttle switch
Fig. 16 Potentiometer type throttle switch
2163
Throttle Switches
Throttle switches form 'part of the electronic control for the
fuel injection system and provide the E.C.U. with information
on throttle operating conditions, Two types of switches can
be used dependant upon the type of information required by
the E.C.U. to perform its function.
Acontact type switch
is fitted to TA? models and is located
on the throttle body in the engine compartment. The sWitch
contacts close when the accelerator pedal is fully depressed.
signalling to the EC.U. to lengthen the
time that the main
injectors are 'open', thus supplying extra fuel for the
acceleration required.
Apotentiometer type switch
is fitted to TRB and Rover 3500
models on the engine plenum chamber In Ime With the
throttle input spindle, This switch is asimple electrical
potentiometer (variable resistance) whose electrical signal to
the
ECU depends upon the position of the throttle spindle
and hence the accelerator pedal. The E.C.U will detect
changes in throttle position
by the voltage output from the
potentiometer. Using this together With information from the
other sensors it
will adjust the fuel Input accordingly. either
for degrees of acceleration and deceleration or for constant
engine speed, When avery sudden acceleration
IS Signalled
to the E,C.U. by the throttle potentiometer. all Injectors are
pulsed to operate once simultaneously to ensure adequate
engine response.

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Coolant Temperature Sensor
This sensor is localed al the top of the engme (TRl) or
between the cylinder heads (TRS and Rover 3500) and
provides coolant temperature mformatlon to the ECU. This
information causes the ECU. to lengthen the time that the
main injectors are 'open' redUCing this lime as the engine
warms up and cutting it off when normal engine operating
temperture is reached. In practice the sensor functions by
modifying an output voltage from the E.CU through an
'earth' return Circuit.
Extra Air Valve
This valve is mounted above awater passage near the Inlet
manifold and registers the same temperature as the engme
coolant. Its purpose
is to provide the additional air required
to maintam asatisfactory engine Idle speed until the engine
reaches normal operating temperature. This air IS taken from
a
point before the throttle butterfly (but after the Air Flow
Meter.
so that the air is registered by the E.CU,) and returned
10 the plenum chamber after the throttle butterfly.
To allow air to pass through the Extra Air Valve. and thus by-
pass the throttle butterfly. an opening in arotatable metal
disc
is aligned with the inlet and outlet tubes on the valve
The position
of this disc is controlled by abi-metal striP
which deflects according 10 the temperature It experiences
As the bi-metal strip heats up it rotates the metal diSC until its
opening no
longer lines up with the air valve tubes and the
extra air source
is reduced and finally terminated as normal
engine
operating temperature is reached. The bi-metal strip
is heated from two sources. the coolant temperature and a
heater coil around the strip. The heater
colliS energised from
the fuel injection system
combined relay while the engine IS
running,
2164
Fig. 17 Coolant tempertute sensor
Fig. 18 Extra air valve 15

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
16
Fig. 1S1 OJlY9'lO Sensor
The Oxygen sensorls) require replacement at the intervals
stated
in the maintenance summary, and areminder lamp
on the fascia
will illuminate at this mileage interval. Please
see your Dealer,
or qualified service outlet, as soon as
convenient after the reminder lamp illuminates.
Overrun Valve
This second air flow control device bleeds air into the engine
inlet manifold, via the piunum chamber, when the manifold
depression is hIgh and thus maintains combustlOn dUring
engine overrun.
The valve operates independantty of the electronIC control
system and on TAJ models
IS mcorporated In the throttle
butterfly connectmg the constant depresslOn region between
the throttle and the Air Flow
Meter measuring flap On ve
models It IS aseparate valve on the sIde of the thrOllle body
Oxygen Sensor
Asmgle sensor IS fitted to TAJ models and two sensors are
fitted to TAe and
Rover 3500 vehicles They are located In
the exhaust system near to the catalyst(s) and. like the
catalyst(sl. reqUire only
UNLEADED fuello be used to prevent
damage to them. These sensors monitor the composition of
exhaust gases leaving the engine
The Internal workmg surfaces of the sensors are coated
wllh
athin platinum layer which IS permeable to gas AspeCial
ceramiC layer protects the electrodes agamst corrOSion and
thiS become conductIVe to
olCyQen atoms at about 600°C
11112°F) If the concentration of oxygen mSlde the sensor
(from the exhaust gasesl differs from that outside the sensor
(atmosphere) avoltage
IS developed between the two
surfaces that changes when the outer electrode has catalytiC
activIty
ThiS voltage IS passed to the ECU which compares
It against areference voltage for Ideal combustion and
adjusts the main injector 'open'
lime accordingly to permit
more or less fuel to be used by the engme
More fuel will use
up the excess oxygen mthe exhaust gas. less fuel Will allow
more oxygen, and so the ideal oxygen content
IS supplied to
permit the catalyst to operate at
ItS best effiCiency
Conunued

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
By usmg oxygen sensor(s) to monitor the eKhausl gases In
this way afeed back closed loop· type of control system can
be Introduced for the fuelln/ecllOn operatIOn
Fig. 20 The general 'closed loop' f.ed back control system
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FUEL IHPtrr IT
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I AIR land I FUEL 1 __ .... 'COMBUSTION I •• ~""I EXHAUST GASES I
2173
FIg. 21 ElectroniC fuel injection ·clo.ed loop' f.ed back control system
17

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
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Fig. 22
Function diagram of electronic fuel injection system components

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
FIg. 23 SchematiC wmng dIagram of electronic fuel injection system components
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