Group 28 Ignition systems
Design and function
Compensation
functions
101
Knock-controlled fuel enrichment
Knock-contro
l
led
fuel
enrichment
means
that the injector opening period
is
extended to
enrich
the fuel/air mixture,
reducing
th
e combustion
temperature and br
in
ging the uncontrolled
combustion under control.
The function
i
s
acti-
vated if the
igni
t
ion
system
control
unit detects
that
knock
is occurring in
all
cylinders
above a certain threshold
value.
On
re
ceiving a
signal from the knock sensor
(2) and
having
established
that knock
present in
all cylinders,
the
con-
trol
unit
connects a terminal
on
the fuel
injection
system
contro
l
unit
to ground,
causing
the latter to transmit
a
signa
l
to
the
injectors
to
extend
the
opening
period.
Kno
c
k
-con
trolled
fuel enrichment
is
a feature
of
EZ
-
117K
o
n
the B230FT
engine,
and
of
all variants
of
EZ-11SK and
EZ
-1
1
6K.
* The function
is
activated
only
w
i
th
in
a certain speed
and
load
range,
i
n
addition
to which a
c
ertain
average
knock
-con
trolled
retar-
dation
must already have been applied in all cylinders.
The following
conditions are
requ
i
r
ed
for
the
intervention of
the knock
-
controlled
fuel enrichment
function
on
the various
ignition systems/engines:
-
EZ
-
l17K on B230FT:
retardation
in
all
c
ylinders
in
response
to
knock
detector signals.
-
EZ
-
115K
on
B280E
/F:
Retardation
of at least 10
°
in
all
cylinders in
response to knock detector
signals
at
engine speeds above
3800 r
/m
in and
above a certain minimum load.
-
EZ
-
1
16K on
8
234 F:
Retardation
of at least
3--4
0
in
cylinders in
response to knock
detector signals at eng
ine
speeds above 3800
r
/min
and
above a certain minimum
lo
ad
.
39
