SAAB 9000. Instruction - page 24

4A•6 Fuel and exhaust systems
to the speed of the vehicle. This has the
effect of transferring torque to the wheel
with most traction.
d) System switches: a pressure switch in
the TCS actuator is activated at a pressure
of 6.0 bars, and this illuminates a TCS
function light on the instrument panel,
informing the driver that the TCS system is
operating and attempting to counteract
wheelspin. If the system develops a fault,
the "TCS CTRL" warning light will be
illuminated permanently. However, if the
TCS system has been in operation for a
long time, the "TCS CTRL" warning light
will flash, to inform the driver that the TCS
system is temporarily inoperative, in order
to prevent overheating of the brakes.
e) Main control switch: the main control
switch is located on the facia panel.
2 In the event of a fault in the traction control
system, first check all relevant wiring for
security. If a fault arises on the road, a back-
up mode can be engaged by fully releasing the
accelerator pedal, then depressing it again. In
this mode, the throttle is operated by a cable.
In back-up mode, engine performance will be
limited, the accelerator pedal will be stiffer,
and the cruise control and air conditioning
systems will be inoperative. Further testing of
the system is best left to a Saab dealer, who
will have the necessary diagnostic equipment
to find the fault quickly. It is not possible to
make any adjustment to the system.
Component renewal
Accelerator pedal potentiometer
3 Working inside the car, disconnect the
wiring plug from the potentiometer (see
illustration).
4 Disconnect the potentiometer arm from the
accelerator pedal.
5 Unbolt and remove the unit.
6 Refitting is a reversal of removal.
Throttle potentiometer/motor
7 Disconnect the wiring plug from the throttle
potentiometer/motor (see illustration).
8 Disconnect the throttle lever.
9 Unbolt and remove the unit.
10 Refitting is a reversal of removal.
6.7 ETS Throttle potentiometer/motor
ETS control module
Warning: If a new control module
is to be fitted, note that it must be
programmed (manual or
automatic transmission) by a
Saab dealer before connecting the wiring
plug (new modules are supplied
unprogrammed). Also note that the module
is extremely sensitive to static electricity,
and it is important to "earth" yourself
before (and while) working on it.
11 Move the left-hand front seat as far
forwards as possible.
12 Lift the carpet, then unbolt and remove the
cover.
13 Disconnect the wiring plug, and remove
the control module from inside the car. On
automatic transmission models, remove the
ASR module from the top of the ETS control
module.
14 Refitting is a reversal of removal.
Warning light
15 Remove the automatic climate control
panel, with reference to Chapter 3.
16 Press out the warning light, and
disconnect the wiring plug.
17 Refitting is a reversal of removal.
Note: The information given in this Chapter is
correct at the time of writing, and applies only
to petrols currently available in the UK. If
updated information is thought to be required,
check with a Saab dealer. If travelling abroad,
consult one of the motoring organisations (or a
similar authority) for advice on the petrols
available, and their suitability for your vehicle.
1 The fuel recommended by Saab is given in
the Specifications at the start of this Chapter,
followed by the equivalent petrol currently on
sale in the UK.
2 RON and MON are different testing
standards; RON stands for Research Octane
Number (also written as RM), while MON
stands for Motor Octane Number (also written
as
MM).
3 All Saab 9000 models are designed to run on
fuel with a minimum octane rating of 91 (RON),
but are more efficient with the higher octane
fuels listed in the specifications.
LH-Jetronic fuel injection
system
The LH-Jetronic fuel injection system is a
microprocessor-controlled fuel management
system, which continuously monitors the
engine using various sensors, and provides
the correct amount of fuel necessary for
complete combustion under all engine
conditions (see illustration). Data from the
sensors is processed in the fuel system
electronic control unit (ECU) in order to
determine the opening period of the
injectors for the exact amount of fuel to be
injected into the inlet manifold. The
system is of the simultaneous type, which
means that all injectors open and close at the
same time. They open once for each
revolution of the crankshaft, except during
cold starting, when they open twice for each
revolution. On Turbo models manufactured up
to 1989, a separate ECU is used to control the
turbocharging function; from this date
onwards, however, the function is
incorporated in the Direct Ignition ECU. Where
a catalytic converter is fitted (later models), a
lambda sensor is incorporated in the LH-
Jetronic system.
The main components of the system are as
follows:
a) ECU: the electronic control unit controls
the entire operation of the fuel injection
system.
b) Injectors: each fuel injector consists of a
solenoid-operated needle valve, which
opens under the commands from the
ECU. Fuel from the fuel rail is then
delivered through the injector nozzle into
the inlet manifold.
c) Airflow meter: the airflow meter
measures the amount of air entering the
engine by means of a hot wire.
d) Temperature sensor: the coolant
temperature sensor monitors the engine
temperature.
e) Auxiliary air valve: the auxiliary air valve
provides additional air when the
engine is cold. It is only fitted to 1985
models.
f) Idle air control valve: the idle air control
valve controls the volume of air bypassing
the throttle butterfly. It is fitted to 1986-on
models.
g) Throttle position switch: the throttle
position switch informs the ECU of the
throttle butterfly position.
h) Fuel pump: the fuel pump is housed in
the fuel tank. The pump housing
6.3 ETS accelerator pedal potentiometer

Fuel and exhaust systems 4A•7
8.1 LH-Jetronic fuel injection system layout
1 Fuel tank
2 Fuel pump
3 Feedpump
4 Fuel filter
5 Fuel injection manifold
6 Fuel pressure regulator
7 Electronic control unit
8 Distributor
9 Ignition coil
10 Temperature sensor
11 Injection valve
12 Vacuum line
13 Inlet manifold
14 Throttle position sensor
15 Idle speed control valve
16 Airflow meter
17 Lambda sensor (catalytic
converter models)
18 Pressure switch (Turbo
models)
19 System relay
20 Fuel pump relay
21 Battery
22 Ignition switch
incorporates a separate feed pump which
supplies the main fuel pump with
pressurised fuel, free of air bubbles.
i) Fuel filter the fuel filter is located behind
the battery in the engine compartment,
j) Lambda sensor: the lambda sensor
provides the ECU with constant feedback
on the oxygen content of the exhaust
gases. The lambda sensor is fitted to later
models with a catalytic converter.
k) Cold start injector a cold start injector is
fitted to certain models, and it injects
additional fuel into the inlet manifold for a
limited period during starting.
Trionic engine management
system
The Saab Trionic engine management
system controls three functions of the engine
from a single electronic control unit (ECU). The
three functions comprise the fuel injection
system, ignition system, and (where
applicable) the turbocharging system. Details
of the ignition function are given in Chapter
5B. The system is microprocessor-controlled,
and the fuel system provides the correct
amount of fuel necessary for complete
combustion under all engine conditions. Data
from various sensors is processed in the ECU,
in order to determine the opening period of the
injectors for the exact amount of fuel to be
injected into the inlet manifold. The system is
of sequential type, where fuel is injected
according to the engine's firing order. When
the ignition is initially switched on and after the
fuel pump is operating, all the injectors
operate for a short period, in order to supply a
small amount of fuel in the vicinity of the inlet
valves. This helps the engine to start quickly.
The main components of the system are as
follows:
a) ECU: the electronic control unit controls
the entire operation of the fuel injection
system, ignition system and turbocharging
system.
b) Crankshaft position sensor: the
crankshaft position sensor provides a
datum for the ECU to calculate the
position of the crankshaft in relation to
TDC.
c) Manifold absolute pressure (MAP)
sensor: the MAP sensor provides a
voltage to the ECU, proportional to the
pressure in the inlet manifold.
d) Inlet air temperature sensor: the inlet air
temperature sensor provides the ECU with
signals which enable it to calculate the
density of the air entering the engine.
e) Engine coolant temperature sensor: the
engine coolant temperature sensor
informs the ECU of the engine
temperature.
f) Throttle position switch: the throttle
position switch informs the ECU of the
throttle butterfly position.
g) Lambda sensor the lambda sensor
provides the ECU with constant feedback
on the oxygen content of the exhaust
gases. The lambda sensor is of Bosch
manufacture.
h) Ignition discharge module: the ignition
discharge module (or cartridge) contains
four HT coils connected directly to the
spark plugs.
i) Injectors: each fuel injector consists of a
solenoid-operated needle valve, which
opens under the commands from the
ECU. Fuel from the fuel rail is then
delivered through the injector nozzle into
the inlet manifold. The injectors are of
Bosch manufacture.
j) Boost pressure control (solenoid) valve:
the boost pressure control valve (also
referred to as the solenoid valve) controls
the operation of the turbocharger. Under
certain conditions (ie in 1st gear), boost
pressure is reduced.
k) Idle air control valve: the idle air control
valve controls the volume of air bypassing
the throttle butterfly. The system maintains
the engine idle speed under all conditions
of load imposed by the alternator, air
conditioning compressor, or when a gear
other than P or N is selected on automatic
transmission models. If there is a break in
the idle air control valve circuit, the valve
opening is set by an internal spring, to
control the engine speed at approximately
1000 rpm.
I) EVAP canister-purge valve: the EVAP
canister-purge valve is operated when the
engine is started, to purge fuel
accumulated in the canister. In order to
allow the lambda sensor to compensate
for the additional fuel, the system is
operated in short phases,
m) Fuel pump: the fuel pump is housed in
the fuel tank. The pump housing
incorporates a separate feed pump which
supplies the main fuel pump with
pressurised fuel, free of air bubbles,
n) Fuel filter: the fuel filter is located
beneath the rear of the car adjacent to the
fuel tank, and filters all fuel from the fuel
pump.
If the system warning light comes on, the
car should be taken to a Saab dealer at the
earliest opportunity. A complete test of the
engine management system can then be
carried out, using a special electronic
diagnostic test unit which is simply plugged
into the system's diagnostic connector.

4A•8 Fuel and exhaust systems
10.6a Use an Allen key to unscrew...
Note: Refer to the warning at the end of
Section 1 before proceeding.
Warning: The following procedure
will merely relieve the pressure in
, the fuel system - remember that
fuel will still be present in the
system components, and to take
precautions accordingly before
disconnecting any of them.
1 The fuel system referred to in this Section is
defined as the tank-mounted fuel pump, the
fuel filter, the fuel injectors, the fuel rail and the
pressure regulator, and the metal pipes and
flexible hoses of the fuel lines between these
components. All these contain fuel, which will
be under pressure while the engine is running
and/or while the ignition is switched on. The
pressure may remain for some time after the
ignition has been switched off, and must be
relieved before any of these components are
disturbed for servicing work.
2 Open the fusebox, and remove fuse 14 (the
fuel pump fuse).
3 Start the engine (if possible) and run it until it
stops. Try to start it twice more, to ensure that
all pressure has been relieved.
4 Disconnect the battery negative terminal,
then refit fuse 14.
10.6b ... and remove the retainers...
5 Place a suitable container beneath the
relevant connection/union to be disconnected,
and have a large rag ready to soak up any
escaping fuel not being caught by the container.
6 Slowly loosen the connection or union nut
(as applicable) to avoid a sudden release of
pressure, and position the rag around the
connection to catch any fuel spray which may
be expelled. Once the pressure is released,
disconnect the fuel line.
Plug or cap the fuel line/union,
to minimise fuel loss and to
prevent the entry of dirt into
the fuel system.
Note: Refer to the warning note at the end of
Section 1 before proceeding. On models with
Trionic engine management, the fuel pump
also incorporates the fuel gauge sender unit;
on models with LH-Jetronic fuel injection, the
fuel pump and sender are separate units (see
Section 12)
Testing
1 To test the fuel pump without removing it,
obtain a graduated container with a capacity
of at least 900 cc. The pump is located in the
fuel tank.
10.13 Remove the light plastic cover
10.14 Disconnecting the wiring plug
10.6c . . . then remove the cover from over
the pump
2 In the engine compartment, disconnect the
return line at the fuel pressure regulator, and
connect a hose between the regulator and the
container.
3 Remove fuses 14 and 22 from the fusebox
with reference to Chapter 12, then connect a
bridging wire between the two terminals to run
the fuel pump. Run the pump for 30 seconds
exactly, then stop it. Check that the pump
delivers a minimum of 900 cc of fuel.
4 Note that a more comprehensive test may
be carried out to ascertain the actual pressure
of the fuel. This test should be carried out by
your Saab dealer, as it involves the use of a
pressure gauge.
Removal
5 Disconnect the battery negative lead.
6 Remove the rear floor panel, then use an
Allen key to remove the cover from over the
fuel pump (see illustrations).
Models with LH-Jetronic fuel
injection
7 Disconnect the wiring plugs from the fuel
pump, feed pump and fuel gauge sender unit,
then move the cover to one side.
8 Unscrew the banjo union, and disconnect
the fuel delivery pipe from the pump. Recover
the sealing washers.
9 Loosen the clip on the pump rubber collar.
10 Lift out the fuel pump and the suction
reservoir, then disconnect the fuel line from
the reservoir, and pull the wiring from the
rubber grommet in the tank. Remove the
pump from inside the car. Cover the aperture
in the top of the fuel tank.
11 With the pump on the bench, separate the
suction reservoir from the pump, and remove
the strainer. Recover the O-ring.
12 Loosen the clip, and disconnect the pump
from the rubber grommet.
Models with Trionic engine
management
13 Where necessary, remove the light plastic
cover from the wiring plugs (see illustration).
14 Disconnect the wiring plug from the top of
the fuel pump (see illustration).
15 Disconnect the fuel delivery and return

Fuel and exhaust systems 4A•9
10.15 Disconnecting the fuel pipes from the
pump
ppes from the pump (see illustration), noting
which is which.
16 The unit is secured by a screwed ring.
Saab technicians use a special tool to
unscrew the ring, but a large pair of grips
(water pump pliers) inserted between the
serrations inside the ring will achieve the same
result. Unscrew and remove the ring (see
llustration). Note the location arrows on the
top of the pump and tank.
17 Carefully lift the pump from the fuel tank,
taking care not to bend the sender arm (see
llustrations).
18 Remove the sealing O-ring from the neck
of the fuel tank (see illustration).
Refitting
Models with LH-Jetronic fuel injection
19 Locate the pump in the rubber grommet,
so that the lip of the grommet is 50 mm above
the top edge of the pump (see illustration).
tighten the clip.
20 Refit the strainer to the pump, then refit
the suction reservoir, using a new O-ring.
Make sure that the relief valve is positioned at
45
0
from the front-facing mark, as shown (see
illustration). Also check that the overall length
of the assembly is as in illustration 10.19.
21 Insert the fuel pump in the fuel tank, so
that the mark on the rubber collar is 45° to the
right when looking towards the front of the car.
Locate the collar on the fuel tank, then refit
and tighten the clip.
22 Refit the fuel delivery pipe and banjo
10.18 Removing the sealing O-ring from the
neck of the fuel tank
10.16 Using a pair of water pump pliers to
unscrew the retaining ring
union, together with new sealing washers, and
tighten securely.
23 Reconnect the wiring, making sure that
each wire is correctly located.
Models with Trionic engine
management
24 Check the sealing O-ring, and if necessary
renew it. Wipe clean the fuel tank neck, then
locate the O-ring.
25 Carefully lower the fuel pump into the
tank, making sure that the location arrows are
correctly aligned with each other.
26 Refit and tighten the screwed ring. Make sure
it is tight enough, otherwise the joint may leak.
27 Reconnect the fuel delivery and return
pipes.
28 Reconnect the wiring plugs to the top of
the fuel pump in their previously-noted
positions.
29 Reconnect the battery negative lead. Run
tho engine and check for leaks.
30 Refit the light plastic cover.
All models
31 Refit the fuel pump cover and the rear
floor panel.
10.17a Removing the fuel pump from the
fuel tank
10.17b Fuel pump removed from the fuel
tank
LH-Jetronic fuel injection system
1 Disconnect the wiring plugs from the airflow
meter and the ECU.
2 Using a bridging wire, connect terminal 21
(yellow/white) and 17 (violet) on the ECU multi-
plug, then use a voltmeter to check that
battery voltage is present at the blue/red
10.19 Correct fitted position of the rubber
grommet above the top edge of the fuel
pump
10.20 Fuel pump relief valve positioning
Testing