Page 321
STARTER PINION
(Starter removed from car)
Dismanting
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Disconnect the feeder cable from the solenoid.
Undo the solenoid retaining screws.
Unhook the solenoid and remove it.
Undo the engaging lever arm locating screw.
Remove the commutator bearing housing screws ( 1).
Pull off the drive housing. Save the rubber and steel
washer (15-16).
Push down the stop ring towards the pinion.
Remove the lock ring with lock ring pliers.
Remove the stop ring and the pinion.
Check the spiral splines on the rotor shaft for burrs.
If there are any, file them off.
,
5"4\B
L
331-5
Page 323
IGNITION SYSTEM
BREAKERLESS IGNITION SYSTEM
Two types of ignition system are used: a conventional
version and a breakerless version.
A conventional ignition system with mechanical breaker
contacts (points) in the distributor is installed in cars
for the European markets (excluding Turbo cars).
J) J) J)
-0
3
This system differs from conventional ignition system as
follows.
The breaker points in the distributor have been replaced
by a transmission unit comprising an impulse transmitter,
an induction coil and a rotor disc. The impulse transmitter
is connected to an electronic control unit in which the
signal from the distributor is converted and amplified.
The electronic control unit is connected to the ignition
coil which is a high-11o(tagecoil that has been specially
adapted to the system.
The breaker function of the electronic control unit is
therefore of the same character as that performed by the
mechanical points in a conventional ignition system.
Thus, the advantage of the breakerless system is that,
thanks to the pulse generator, there is not mechanical
wear affecting the setting of the timing.
S 6461
· CONVENTIONAL
IGNITION
SYSTEM
The breakerless ignition system with an electromagnetic
pulse generator in the distributor and an electronic control unit performing the task of conventional points
is installed in cars for the USA market and in Turbo cars.
BREAKER LESS IGNITION
S 6245
SYSTEM
SAAB
340-1
Page 324
7
8
S 6306
BREAKER LESS IGNITION
1. Battery
2. Ignition switch
3. Electronic control unit
4. Compensating resistor
5. Distributor
6. Ignition coil
ELECTRONIC
340-2
CONTROL
UNIT
SYSTEM
7. Screened cable
8. To fuel pump relay, tachometer and TSI socket
9. To relay terminal 87a (connected at start)
COMPENSATING
SA.Ml
RESISTOR
Page 325
the coil (when the rotor poles are in line with the stator
poles).
This corresponds to the breaking of the points in a conventional ignition system.
Operating principle
A sinusoidal control voltage is present in the induction coil,
which alternates rapidly between positive and negative polarity. This alternation in polarity is utilized to transmit
pulses. The pulse transmitted is governed by the engine
speed and varies between 0.3 V and 100 V. The signal is
then converted and amplified in the electronic control
unit. When the sinusoidal voltage passes through zero,
the ignition voltage is induced in the secondary circuit of
Spanning lr6n
lmpulsgenerator
Signal from
Impulse generator
Primllrstrom
Primary current
I
I
Sluten
Closed
Bruten
Open
o'
9Cf
25°
115°
--
Rotationsviri<el
Rotation deg'ees
S 6464
Ti
To relay, terminal 87 a
Compensating
resistor
I
cb
1·
-
\
~
-7
-
-
-
Ignition coil
Sta bi Iization
~) _J
I
I
Impulse transmitter
in distributor
l
-
I
I
<e>ri
'
Compensating
resistor
I
I
-
-
..
I
I--=::=T i
I
-
~
To distributor
-
Trigger
Dwell angle
control
Dr iv.er
-
l-
I
-
------
-
-
-
I
Darlington
output
stage
I
-
-
-
__j
S 5902
BLOCK DIAGRAM
340-3
Page 326
speed, thereby providing a high ignition voltage even at
high engine speed. At the driver, the signal is amplified
once again and proceeds to the Darlington output stage.
Current now flows through the primary circuit of the
ignition coil.
At the moment of ignition, which occurs when the sinusoidal signal passes through zero, the ignition voltage is induced in the secondary circuit of the coil.
Block diagram to illustrate operating principle
In the input stage, which is designed in the form of a
Schmitt trigger, the sinusoidal signal from the distributor
is amplified and converted to a rectangular pulse. The
regulation of the dwell angle adapts the time of the current flow through the output transistor and the ignition
coil to the engine speed. In contrast to the constant dwell
angle in a conventional ignition system, the electronic
system increases the dwell angle with increasing engine
Primarstrom
Primary current
I
I
Sluten
Closed
Bruten
Open
900
25°
115°
--
Rotationsvinkel
Rotation degrees
S 6660
80
70
\
\
60 .
50
40
Kamvinkel
Dwell
~
"---
so·
~
10·
so·
so·
40"
30"
30"
20·
20·
10·
10·
I
1000
2000
3000
4000
5000
6000
Vevaxelvarv / min
Crankshaft rpm
S 6661
340-4
SA.Ml
Page 327
IGNITION COIL
GENERAL
The ignition coil, manufactured by Bosch is mounted on
the radiator fan housing.
The breakerless ignition system has a special ignition coil
which should not be confused with conventional coils.
This coil provides a voltage roughly 30 per cent higher
than that provided by coils in conventional systems. The
breakerless system also incorporates a compensating resistor designed to Iimit the primary current at low
engine speeds. The compensating resistor is located between the electronic control unit and the side panel.
IGNITION COIL
REMOVING
1. Disconnect the wiring from the coil
2. Undo the clamping screws and withdraw the coil.
INSTALLING
1. Tighten the screw to clamp the coil in position.
2. Connect the wiring. See fig.
INSPECTING
1. Disconnect the wiring.
2. Connect test equipment and check the coil as follows:
a. Measure the primary winding resistance between
terminals 1 and 15. Test value, see Group 0.
b. Measure coil performance in volts or spark lenght.
Note: Check that the breaker gap and closing angle
of the distributor are correct.
NOTE
Faults, if present, can often only be detected when
the coil has warmed up. In case of doubt, leave the
coil connected under load on the test bench for half
an hour; it should still function perfectly at the end
of this time.
341-1
Page 328
,
1
ll
1
Page 329
DISTRIBUTOR
With mechanical breaker points
GENERAL
The distributor is made by Bosch and is mounted on the
front of the engine block, i.e. at the clutch end of the engine. It rotates counter-clockwise and is driven by a worm
gear from the idler shaft. The distributor is designed for
centrifugal- and vacuum regulation; the centrifugal regulator controls the ignition setting relative to the engine
speed, while the vacuum regulating system controls the
ignition setting in relation to the load. The order of firing
(cylinders numbered from rear to front).
is 1-3-4-2
DISTRIBUTOR
1. Distributor cap
2. Rotor
3. V~cuum control unit
4. Breaker points
5. Low-voltage wire
6. Spring clip
7. Drive gear
S4764
REMOVING
1. Disconnect the i_gnition cables.
2. Release the spring clips and take off the distributor
cap.
3. Disconnect the low-voltage wire from the ignition coil.
4. Pull off the vacuum hose.
5. Crank the engine until the flywheel marking is at the
ignition position on cylinder No. 1. (See Group 0, basic ignition advance.)
6. Remo_vethe distributor mounting retaining screw (13
mm across flats).
7. Pull the distributor away from the engine.
342-1
Page 330
INSTALLING
1.
Check the flywheel position, (see Group 0, basic
ignition advance), which shall correspond with the
ignition position on cylinder No. 1.
2.
Rotate the distributor shaft so that the rotor (distributor arm) will point approx. 50° clockwise from
the mark on the edge of the distributor housing
which indicates the firing position for No. 1 cylinder.
3.
Fit the distributor with the mark on the edge of
the distributor housing directed towards the cylinder head.
Engage the gears with each other and rotate the engine slightly forward and backwards until the distributor shaft engages the oil pump. On assembly,
the rotor will be turned approx. 50° anti-clockwise
owing to the pitch of the gear teeth.
4.
5.
6.
7.
8.
9.
342-2
Check that the basic setting mark for the flywheel
coincides with the mark on the flywheel cover (firing position for No. 1 cylinder).
Also check that the rotor can be pointed at the
mark on the edge of the distributor housing, i.e.
the breaker position of the breaker point for No. 1
cylinder.
Tighten the screw slightly (but not so hard that
the distributor cannot be turned).
Connect the low-voltage wire to the ignition coil.
Connect the cam angle meter, switch on, and check
and adjust the cam angle at starter speed.
Put on the distributor cap, secure it with the spring
clips, and connect the ignition cables.