ON-BOARD
DIAGNOSTICS
1
PC
INTERFACE
SOFTWARE
Pressure
(k.Pa)
-
This
is
the
pressure that exists
in
the
intake
manifold.
At
no-load
the
kPa
will
be
lower
than
at
full
load.
The
wider
the
throttle
plate
is
open,
the
closer it
gets
to
atmosphere
which
is
about
100
kPa.
Typically a genset
running
at
no-load
will
see
a kPa
value
around
30,
while
at
full
load
it
would
be
around
90
kPa.
If the kPa
is
stuck
at
70
and
never
moves
then
there
is
a problem
with
either
the
MAP
sensor
or the
wiring
to
the
MAP
sensor,
as
70
is
a
default
value
that
is
in
the
code.
WB
Heater Set-point -
This
is
the
set-point
in
millivolts of
the
heater
temperature
in
the
Wideband
02
Sensor.
Curently
in
all
the
units
that
do
not
have
an
idle
mode,
the
set
point
is
893.
In
other
units
the
set-point
will
vary
but
wll
be
displayed
in
this
box.
WB
Current Temp -
This
is
the
actual
value
in
millivolts of ·
the
heater
temperature
in
the
Wideband
02
Sensor.
If
the
heater
is
working
properly,
you
will
typically see values
stay
within
20
millivolts
of
the
set-point. The higher
the
number
is,
the
colder
the
heater
is.
1)rpically a reading
in
the
4000
area
means
that
the
heater
is
not
working
at
all.
If
the
value
is
swinging
dramatically
above and below
the
set-point,
the
sensor
is
probably
failing.
The
sensor should be
replaced.
Lambda -
Lambda
represents the
ratio
of
the
amount present
in
a
combustion
chamber
compared
to
the
amount that
should
have
been present in order to obtain "prefect"
combustion.
Thus,
when
a mixture contains exactly
the
amount
of
oxygen
required
to
bum
the
amount of fuel
present
the
ratio
will
be
one
to
one
and
lamba
will
equal
1,000.
If
the
mixture
contains
too
much
oxygen
for
the
amount
of
fuel
(a
lean
mixture), larnba
will
be greater
then
1,000.
If a
mixture
contains
too
little oxygen for
the
amount
of
fuel
(a
rich
mixture),
Iamba
will be less than
1,000.
Perfect
combustion
requires
an
air/fuel ratio of approximately
14.7:1
(by
weight)
under
normal
condtions. Thus a
lean
air/fuel
ratio
of,
say,
16:
1
would
translate to a lambda
value
of
1.088.
(To
calculate, divide
16
by
14.7.)
A lamba of
.97
would
indicate
an
air/fuel
ratio of
14.259:1
(derived
by
multiplying
.97
by
14.7).
In
our
applications
we
want
to
see
lambda reading
around
1,000.
Because
of
the
combustion involved this number
will
constantly
be
changing,
ideally you should see the value of
lamba
fluctuating
slightly
above
and
below the
1,000
target.
Immediately
after a startup it
is
typical
to
see
a rich
readings
for
lambda.
This
is
part of the startup process
and
usually
takes
a
couple
of
minutes
for sensors
to
warm
up
and
take
control
of
the
air
fuel
mixture.
If
you
see
a
problem
in
this
area
first
check
the
Wideband
heater
value
to
make
sure
that the heater
is
working.
Remember
that
it
takes
about
three
minutes after starting
an
engine
for
it
to
be
totally
in
control. Physically
remove
the
sensor
and
check
it
for
corrosion
and
build up of
deposits.
from
the
water
being
injected through the exhaust. Salt
water
deposited
on
the
senor
will
be
very
damaging.
If
there
is
any
evidence
of build
up,
replace the
sensor.
65
After
checking
the
senor
and
the
genset
is
running
too
rich,
ch!!ck
the
air
intake screens
and
spark plugs
to
make
sure
.
they
are
clean
and
functioning
properly.
If
the genset
is
running
too
lean, check the fuel
)evel_s
and
the
quality
of
the
fuel.
Water
in
the
gas
will
cause
the
genset
to
run
Jean.
Lambda
PW
Trim -
Is
the fueling
trim
precentage
that
the
wideband
oxygen sensor
is
contributing.
In
most
cases
15%
is
the
maximum.
"'
Wideband
P,
I & D Term - These values
are
the
lambda
value
controlling
terms.
Their job is
to
keep
the
lambda
reading at 1,000
by
enriching or enleaning
the
fueling.
Lambda P & I Term - These values are the
lambda
value
controlling
terms.
Their job is
to
keep the lambda
reading
at
1,000
enriching or enleaning
the
fueling.
NB
SIT
- (Narrowband Short
Term
Trim)
If
you
genset
is
equipped with a narrowband oxygen
sensor,
this
will
be
the
value
of
its
contribution. Max contribustion
is
1 %.
Stepper Pos (steps) - The throttle shaft
is
controlled
by
a
stepper
motor.
The value displayed
is
in
steps.
Zero
steps
being
the
closed
position.-
Most units
will
run
at
no
load
in
the
20
to
30 steps range. These
values
will
vary
from
engine
to
engine.
Pulse Width -
Is
the fueling duration
in
milliseconds
(ms).
The
value
will
be lower
at
no
load
than
at
full
load.
lp
Current -
Is
the
electrical'value equivalent of
the
Lambda
reading.
There
is
not
much
to
learn
from
this
number.
Main Fuel Comp
(%)
-
Is
the
fueling compensation
that
is
derived
from
a value
in
the
fuel
table,
which
is
based
on
the
engine
rpm
and
the MAP pressure.
Air Temp and Engine Temp Comp
(%)
-
Is
the
fueling
compensation based
on
the
air
temperature
and
engine
temperature. This value can be both positive
and
negative.
This
value
is
added or subtracted
from
the main
fuel
compensation value.
Frequency
Option - Tis
the
value
of
the
speed selector
on
the
ECU,
whether it
is
50 or
60
Hz.
Some interfaces
may
not
show
this
column but
will
display
the
Frequency
Option
in
the
Title
area
at
the
top
of the data
log.
The Generator Frequency -
Is
a
function
of engine
speed.
For most applications,
50
Hz operation
is
with
an
engine
speed
of
1500
rpm,
while
60
Hz
operation is
with
an
engine
speed
of
1800
rpm.
Note: Belt drive applications will be
different, check your
owners
manual
for
engine speed.
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