<s>
An	O
engine	B-Device
control	I-Device
unit	I-Device
(	O
ECU	O
)	O
,	O
also	O
commonly	O
called	O
an	O
engine	B-Device
control	I-Device
module	I-Device
(	O
ECM	O
)	O
,	O
is	O
a	O
type	O
of	O
electronic	B-Device
control	I-Device
unit	I-Device
that	O
controls	O
a	O
series	O
of	O
actuators	B-Algorithm
on	O
an	O
internal	O
combustion	O
engine	O
to	O
ensure	O
optimal	O
engine	O
performance	O
.	O
</s>
<s>
It	O
does	O
this	O
by	O
reading	O
values	O
from	O
a	O
multitude	O
of	O
sensors	O
within	O
the	O
engine	O
bay	O
,	O
interpreting	O
the	O
data	O
using	O
multidimensional	O
performance	O
maps	O
(	O
called	O
lookup	B-Data_Structure
tables	I-Data_Structure
)	O
,	O
and	O
adjusting	O
the	O
engine	O
actuators	B-Algorithm
.	O
</s>
<s>
If	O
the	O
ECU	O
has	O
control	O
over	O
the	O
fuel	O
lines	O
,	O
then	O
it	O
is	O
referred	O
to	O
as	O
an	O
electronic	B-Device
engine	I-Device
management	I-Device
system	I-Device
(	O
EEMS	O
)	O
.	O
</s>
<s>
The	O
whole	O
mechanism	O
of	O
the	O
EEMS	O
is	O
controlled	O
by	O
a	O
stack	O
of	O
sensors	O
and	O
actuators	B-Algorithm
.	O
</s>
<s>
The	O
throttle	B-Algorithm
position	I-Algorithm
sensor	I-Algorithm
tells	O
the	O
ECU	O
how	O
far	O
the	O
throttle	O
plate	O
is	O
opened	O
when	O
the	O
accelerator	O
(	O
gas	O
pedal	O
)	O
is	O
pressed	O
down	O
.	O
</s>
<s>
Air	O
–	O
fuel	O
mixture	O
control	O
of	O
carburettors	O
with	O
computers	O
is	O
designed	O
with	O
a	O
similar	O
principle	O
,	O
but	O
a	O
mixture	O
control	O
solenoid	O
or	O
stepper	B-Algorithm
motor	I-Algorithm
is	O
incorporated	O
in	O
the	O
float	O
bowl	O
of	O
the	O
carburettor	O
.	O
</s>
<s>
The	O
engine	O
RPM	O
is	O
monitored	O
by	O
the	O
crankshaft	B-Algorithm
position	I-Algorithm
sensor	I-Algorithm
,	O
which	O
plays	O
a	O
primary	O
role	O
in	O
the	O
engine	O
timing	O
functions	O
for	O
fuel	O
injection	O
,	O
spark	O
events	O
,	O
and	O
valve	O
timing	O
.	O
</s>
<s>
Idle	O
speed	O
is	O
controlled	O
by	O
a	O
programmable	O
throttle	O
stop	O
or	O
an	O
idle	O
air	O
bypass	O
control	O
stepper	B-Algorithm
motor	I-Algorithm
.	O
</s>
<s>
Early	O
throttle	O
body	O
injection	O
(	O
TBI	O
)	O
systems	O
used	O
an	O
idle	O
air	O
control	O
stepper	B-Algorithm
motor	I-Algorithm
.	O
</s>
<s>
Such	O
a	O
static-start	O
engine	O
would	O
provide	O
the	O
efficiency	O
and	O
pollution-reduction	O
improvements	O
of	O
a	O
mild	O
hybrid-electric	O
drive	O
,	O
but	O
without	O
the	O
expense	O
and	O
complexity	O
of	O
an	O
oversized	O
starter	O
motor	O
.	O
</s>
<s>
Programming	O
an	O
ECU	O
typically	O
requires	O
interfacing	O
the	O
unit	O
with	O
a	O
desktop	O
or	O
laptop	O
computer	O
;	O
this	O
interfacing	O
is	O
required	O
so	O
the	O
programming	O
computer	O
can	O
send	O
complete	O
engine	O
tunings	O
to	O
the	O
engine	B-Device
control	I-Device
unit	I-Device
as	O
well	O
as	O
monitor	O
the	O
conditions	O
of	O
the	O
engine	O
in	O
realtime	O
.	O
</s>
<s>
Connection	O
typically	O
used	O
in	O
this	O
interface	O
are	O
either	O
USB	B-Protocol
or	O
serial	O
.	O
</s>
<s>
By	O
modifying	O
these	O
values	O
while	O
monitoring	O
the	O
exhausts	O
using	O
a	O
wide	O
band	O
lambda	O
probe	O
,	O
engine	O
tuning	O
specialists	O
can	O
determine	O
the	O
optimal	O
fuel	O
flow	O
specific	O
to	O
the	O
engine	O
speed	O
's	O
and	O
throttle	B-Algorithm
position	I-Algorithm
.	O
</s>
<s>
These	O
data	O
stacks	O
,	O
which	O
are	O
almost	O
always	O
digital	B-General_Concept
,	O
talk	O
to	O
the	O
ECU	O
using	O
one	O
of	O
several	O
protocols	O
including	O
RS-232	O
or	O
CANbus	B-Protocol
.	O
</s>
<s>
MAP	O
:	O
Manifold	B-Algorithm
Absolute	I-Algorithm
pressure	I-Algorithm
.	O
</s>
<s>
CKP	O
:	O
Crank	B-Algorithm
Shaft	I-Algorithm
Position	I-Algorithm
.	O
</s>
<s>
TP	O
:	O
throttle	B-Algorithm
position	I-Algorithm
.	O
</s>
<s>
The	O
development	O
of	O
integrated	O
circuits	O
and	O
microprocessors	B-Architecture
made	O
engine	O
control	O
economically	O
feasible	O
in	O
the	O
1970s	O
.	O
</s>
<s>
In	O
the	O
early	O
1970s	O
,	O
the	O
Japanese	O
electronics	O
industry	O
began	O
producing	O
integrated	O
circuits	O
and	O
microcontrollers	B-Architecture
for	O
engine	O
control	O
in	O
Japanese	O
automobiles	O
.	O
</s>
<s>
The	O
Ford	O
EEC	O
(	O
Electronic	O
Engine	O
Control	O
)	O
system	O
,	O
which	O
utilized	O
the	O
Toshiba	O
TLCS-12	O
microprocessor	B-Architecture
,	O
went	O
into	O
mass	O
production	O
in	O
1975	O
.	O
</s>
<s>
Hybrid	B-Device
digital	B-General_Concept
or	O
analog	O
designs	O
were	O
popular	O
in	O
the	O
mid-1980s	O
.	O
</s>
<s>
This	O
used	O
analog	O
techniques	O
to	O
measure	O
and	O
process	O
input	O
parameters	O
from	O
the	O
engine	O
,	O
then	O
used	O
a	O
lookup	B-Data_Structure
table	I-Data_Structure
stored	O
in	O
a	O
digital	B-General_Concept
ROM	B-Device
chip	I-Device
to	O
yield	O
precomputed	O
output	O
values	O
.	O
</s>
<s>
The	O
ROM	B-Device
type	O
of	O
system	O
is	O
amenable	O
to	O
tuning	O
if	O
one	O
knows	O
the	O
system	O
well	O
.	O
</s>
<s>
Modern	O
ECUs	O
use	O
a	O
microprocessor	B-Architecture
which	O
can	O
process	O
the	O
inputs	O
from	O
the	O
engine	O
sensors	O
in	O
real-time	B-General_Concept
.	O
</s>
<s>
An	O
electronic	B-Device
control	I-Device
unit	I-Device
contains	O
the	O
hardware	O
and	O
software	O
(	O
firmware	B-Application
)	O
.	O
</s>
<s>
The	O
main	O
component	O
on	O
this	O
circuit	O
board	O
is	O
a	O
microcontroller	B-Architecture
chip	I-Architecture
(	O
MCU	O
)	O
.	O
</s>
<s>
The	O
software	O
is	O
stored	O
in	O
the	O
microcontroller	B-Architecture
or	O
other	O
chips	O
on	O
the	O
PCB.	O
,	O
typically	O
in	O
EPROMs	B-General_Concept
or	O
flash	B-Device
memory	I-Device
so	O
the	O
CPU	O
can	O
be	O
re-programmed	O
by	O
uploading	O
updated	O
code	O
or	O
replacing	O
chips	O
.	O
</s>
<s>
This	O
is	O
also	O
referred	O
to	O
as	O
an	O
(	O
electronic	O
)	O
Engine	B-Device
Management	I-Device
System	I-Device
(	O
EMS	O
)	O
.	O
</s>
<s>
Sophisticated	O
engine	B-Device
management	I-Device
systems	I-Device
receive	O
inputs	O
from	O
other	O
sources	O
,	O
and	O
control	O
other	O
parts	O
of	O
the	O
engine	O
;	O
for	O
instance	O
,	O
some	O
variable	O
valve	O
timing	O
systems	O
are	O
electronically	O
controlled	O
,	O
and	O
turbocharger	O
waste	O
gates	O
can	O
also	O
be	O
managed	O
.	O
</s>
<s>
The	O
Controller	B-Protocol
Area	I-Protocol
Network	I-Protocol
or	O
CAN	B-Protocol
bus	I-Protocol
automotive	O
network	O
is	O
often	O
used	O
to	O
achieve	O
communication	O
between	O
these	O
devices	O
.	O
</s>
<s>
General	O
Motors	O
 '	O
(	O
GM	O
)	O
first	O
ECUs	O
had	O
a	O
small	O
application	O
of	O
hybrid	B-Device
digital	B-General_Concept
ECUs	O
as	O
a	O
pilot	O
program	O
in	O
1979	O
,	O
but	O
by	O
1980	O
,	O
all	O
active	O
programs	O
were	O
using	O
microprocessor	B-Architecture
based	O
systems	O
.	O
</s>
<s>
The	O
high	O
volume	O
ECU	O
that	O
was	O
installed	O
in	O
GM	O
vehicles	O
from	O
the	O
first	O
high	O
volume	O
year	O
,	O
1981	O
,	O
onward	O
was	O
a	O
modern	O
microprocessor	B-Architecture
based	O
system	O
.	O
</s>
<s>
This	O
process	O
first	O
saw	O
fruition	O
in	O
1980	O
with	O
fuel	O
injected	O
Cadillac	B-Application
engines	O
,	O
followed	O
by	O
the	O
Pontiac	O
2.5L	O
I4	O
"	O
Iron	O
Duke	O
"	O
and	O
the	O
Chevrolet	O
5.7L	O
V8	O
L83	O
"	O
Cross-Fire	O
"	O
engine	O
powering	O
the	O
Chevrolet	O
Corvette	O
in	O
1982	O
.	O
</s>
<s>
The	O
1990	O
Cadillac	B-Application
Brougham	O
powered	O
by	O
the	O
Oldsmobile	O
5.0L	O
V8	O
LV2	O
engine	O
was	O
the	O
last	O
carbureted	O
passenger	O
car	O
manufactured	O
for	O
sale	O
in	O
the	O
North	O
American	O
market	O
(	O
a	O
1992	O
Volkswagen	O
Beetle	O
model	O
powered	O
by	O
a	O
carbureted	O
engine	O
was	O
available	O
for	O
purchase	O
in	O
Mexico	O
but	O
not	O
offered	O
for	O
sale	O
in	O
the	O
United	O
States	O
or	O
Canada	O
)	O
and	O
by	O
1991	O
GM	O
was	O
the	O
last	O
of	O
the	O
major	O
US	O
and	O
Japanese	O
automakers	O
to	O
abandon	O
carburetion	O
and	O
manufacture	O
all	O
of	O
its	O
passenger	O
cars	O
exclusively	O
with	O
fuel	O
injected	O
engines	O
.	O
</s>
<s>
In	O
1988	O
Delco	O
(	O
GM	O
's	O
electronics	O
division	O
)	O
,	O
had	O
produced	O
more	O
than	O
28,000	O
ECUs	O
per	O
day	O
,	O
making	O
it	O
the	O
world	O
's	O
largest	O
producer	O
of	O
on-board	O
digital	B-General_Concept
control	O
computers	O
at	O
the	O
time	O
.	O
</s>
<s>
In	O
aeronautical	O
applications	O
,	O
the	O
systems	O
are	O
known	O
as	O
"	O
FADECs	O
"	O
(	O
Full	O
Authority	O
Digital	B-General_Concept
Engine	O
Controls	O
)	O
.	O
</s>
<s>
This	O
is	O
due	O
to	O
the	O
common	O
configuration	O
of	O
a	O
carbureted	O
engine	O
with	O
a	O
magneto	B-Algorithm
ignition	I-Algorithm
system	O
that	O
does	O
not	O
require	O
electrical	O
power	O
generated	O
by	O
an	O
alternator	B-Algorithm
to	O
run	O
,	O
which	O
is	O
considered	O
a	O
safety	O
advantage	O
.	O
</s>
