Sun Microsystems MCS 2000 SL - Page 69

the Air/Fuel ratio
at
which
the fuel
burns
most efficiently,
is
called
"Stoichiometric"
point.
This is
also the
point
at
which HC
and CO emissions
are
lowest
and
CO2
is
highest.
t
F nEx
ltu
<
c
.9
o
o
E3
aa
cO
o-
;.9
E
U
t
6
2
O2
o
Ai./Frl Rrlb
SloadrldrrtrE
hnt
As
shown
CO,
high
Figure
35, Ajr Fuel
Ratio
above, the
point
at which
most
efficient
combustion
(low
HC
and
COz) occurs is
approx'imately
14,7
: 1
air/fuel ratio
Note
This
point
may
vary
slightly
because of the
difference in fuel
composition.
Testing
of
vehicles
today,
and tomorrow,
on
vehicles
fitted
with
catalytic
converters
and
engine management
systems,
has made
fuel
system
adjustments
more
difficult than
before. The
new
computer
engine
management
will maintain
correct
air/fuel ratios
with very
little
error,
but
only if
the system
inputs
are operating
correctly.
Carbon
Dioxide
Co2
and
oxygen
02 are the
keys to
proper
adjustment
of
today's
electronic
carburettors
and fuel injection
systems.
There
is
no
compromise
on
modern
engines
for
the
correct settings. We
are
now
jn
the
era when
all carburettion,
injection
system settings
are
critical.
It
is
only
by us'ing
the four
gas
method
of
ana'lysis
that
problems
can
be
accurately
diagnosed
Page
63
THE KEY
-
AIR/FUEL
RATIO
I
t
L