Group
28
Ignition systems
Design and function
-
System descriptions
2
24
EZ
-
117K
EZ-117K
B230FIFT
(740
:
B 230
F
/
FT
;
760
:
B 230
The
control
unit
(1 computes
th
e op
timu
m
timing based
on signals
from the
various
sensors and
tran
smits
ignition
pulses
t
o
the power stage
(
2) at
exactly
the right
ins
tant
.
At this point
,
the power stage interrupts the current
in
the
primary winding of the ignition
coil
(3)
.
The high
-
tension
cu
r
rent induced in
th
e
secondary is delivered to
the
appro-
priate spark plug
by the distributor
(4).
The timing
is computed
by the
contro
l
un
i
t
on
the basis
of
th
e
following
information
:
-
The
engine load signal
is
supplied
by the fuel in
j
ection system
(lH
·
2.21 control
unit (12) wh
ic
h
,
in
turn
,
is
supplied
with
load signals by
the
mass meter
.
- A Hall
generator in
the distributor
(4) supplies
an
engine speed and crankshaft
pos
i
tion
signaL
-
Knock
is
indicated by
the knock
sensor
(2
4)
.
Closure of
the thrott
le
is
in
d
ica
ted
by
the
throttle switch
(
19
).
- Any tendency
of
the
engine
t
o
overheat is
i
ndicated by
a therm
os
tat
(20).
In th
is
event
,
the
con
trol
advances
the timing
by
if
the throttle
is
closed
. (
Th
i
s applies only
t
o
B
230
FT
variants.!
49