130-18
FUEL
INJECTION
The
engine
coolant
temperature
(ECT)
sensor
sends
con-
tinuous
engine
coolant
temperature
information
to
the
ECM
.
Fig
.
26
.
Mass
air
flow
sensor
terminalidentifcation
on
carswith
DME
As
temperature
increases
sensor
resistance
decreases
.
M3
.1
fuel
injection
.
Mass
air
flow
sensor
(hot
film),
testing
and
replacing
MOTE-
A
burn-off
cycle
is
not
used
on
hot
film
sensors
.
8
.
With
ignition
off,
disconnect
harness
connector
from
air
ECT
Sensor
Location
flow
sensor
.
Using
a
digital
multimeter,
check
resis-
"
M50/S50US
engine
............
left
side
of
cylinder
tance
at
terminals
listed
.
head
under
intake
manifold
Air
Flow
Sensor
Test
Values
(DMEM3
.1)
"
Terminals
5
and
6
.
.
.
.........
..
.
..
....
3-4
ohms
If
any
faults
are
found,
check
wiring
lo
and
from
the
ECM
.
Make
ECM
pinout
test
as
listed
in
See
Table
i
.
Main
power
to
air
flow
sensor
comes
from
DME
main
relay
.
On
cars
with
DME
M3
.3
.1
a
hot
film
mass
air
flow
sensor
is
used
.
When
the
engine
is
running,
a
current
is
used
lo
heat
a
thinfilm
in
the
center
of
the
sensor
.
This
current
is
electroni-
cally
converted
into
a
voltage
measurement
corresponding
to
the
mass
of
intake
air
.
If
thehot
film
breaks
or
if
there
is
no
output
from
the
air
flow
sensor,
the
ECM
automatically
switches
to
a
"limp-home"
mode
and
tucos
on
the
Check
Engine
light
.
The
engine
can
usually
be
started
and
driven
.
The
air
flow
sensor
has
no
inter-
nal
moving
parts
and
cannot
be
senricedor
adjusted
.
CA
UTION-
Use
only
a
digital
multimeter
when
checking
the
mass
air
flow
sensor
.
An
analogmetercan
dam-
age
the
air
flow
sensor
.
BOSCH
DME
M3
.
1
AND
M32
.1
COMPONENT
TESTS
AND
REPAIRS
1
.
Disconnect
harnessconnector
from
air
flow
sensor
.
2
.
Turn
ignition
on
and
check
for
voltage
and
ground
at
connector
.
There
should
beground
at
pin
1
.
There
should
be
positive
(+)
battery
voltage
at
pin
3
.
If
any
faults
are
found,
check
wiring
to
and
from
ECM
.
Make
ECM
pinout
test
.
See
Table
j
.
NOTE-
Positive
(+)
battery
voltage
to
air
flow
sensor
comes
from
DME
main
relay
when
the
ignition
is
switch
on
orengine
running
.
Engine
coolant
temperature
(ECT)
sensor,
testing
and
replacing
0012704
Fig
.
27
.
Engine
coolant
temperature
(ECT)
sensor
(A)
is
located
be-
neath
top
engine
cover
(B)
and
crankcase
vent
hose
(C)
.
M52
engine
shown
.
M50
is
similar
.
1
.
Check
ECM
reference
voltage
to
sensor
:
"
Disconnect
harnessconnector
from
ECT
sensor
.
"
Turn
ignition
keyon
.
"
Check
for
5
volts
between
supply
voltage
wire
(brown/red)
wire
of
harness
connector
and
ground
.
"
Turn
ignition
key
off
.
"
If
voltage
is'
not
present
or
incorrect,
check
wiring
from
ECM
and
check
referencevoltage
output
at
ECM
(pin
78)
.
See
Table
i
(DM
E
3
.1)
or
Table
j
(DME
3
.3
.1)
2
.
Check
ECT
sensor
resistance
:
"
With
harnessconnector
disconnected,
check
resis-
tance
acrosssensor
terminals
.
"
Compare
tests
results
to
values
in
Table
f
.
NOTE-
NOTE-
"
The
Ole
speed
control
valve
signal
can
be
checked
The
intake
manifold
is
held
in
place
with
7
nuts
from
using
a
duty
cycle
meter
(or
dwellmeter)
.
Connect
the
above
and
2
support
bracket
bolts
from
undemeath
.
On
meter
to
the
valve
following
the
manufacturer's
in-
DME
3
.1
cars,
carefully
disconnect
the
idleair
hose
from
structions
.
Turn
on
the
WC
or
create
a
larga
air
leak
theintake
manifold
when
lifting
the
manifold
off
.
For
more
and
check
that
the
meter
reading
reacts
while
the
idle
information,
sea
113
Cylinder
HeadRemovaland
In-
speed
remainssteady
.
stallation
.
"
There
are
some
additional
inputs
to
the
control
mod-
ule
that
affect
idle
speed
(Le
.
throttle
position,
AIC-on
5
.
Disconnect
al¡
necessary
hoses
andremove
idle
speed
signals,
andAIT
Drive
position)
.
Check
these
signals
control
valve
.
if
idle
problems
persist
.
See
Tabla
i
orTable
j
.
Idle
speed
control
valva,
replacing
The
idle
speed
control
valve
is
mounted
beneath
the
intake
manifold
.
Accessing
the
valva
is
best
accomplishedby
first
re-
moving
the
intake
manifold
.
NOTE-
¡tis
recommended
that
the
intake
manifold
gaskets
be
replaced
whenever
the
intake
manifold
is
removed
.
1
.
Remove
top
enginecovers
from
engine
.
See
Fig
.
31
.
FUEL
INJECTION
130-21
6
.
Installation
is
reverse
of
Removal
.
Use
new
gaskets
when
installing
intake
manifold
.
NOTE-
Poor
driveability
may
be
noticed
afterinstalling
a
re-
placement
idle
speed
control
valve
.
After
about
10
min-
utes
of
driving,
the
system
will
adapt
the
base
setting
of
the
valva
and
the
idle
speed
should
retum
to
normal
.
Tightening
Torque
"
Intakemanifold
to
cylinder
head
(M7)
........
..
.
15±2
Nm
(11
ti
ft-Ib)
BOSCH
DME
M5
.2
COMPONENT
REPLACEMENT
On-Board
Diagnostics
11
(OBD
II)
is
incorporated
into
the
Bosch
DME
M5
.2
engine
management
systems
used
on
the
M44
engine
.
OBD
II
is
capable
of
detecting
a
full
range
of
faults
.
When
faults
are
detected,
a
Diagnostic
Trouble
Code
(DTC)
is
stored
in
the
system
ECM
.
The
Check
Engine
warn-
ing
light
will
also
come
on
if
an
emissions-relatad
fault
is
de-
tected
.
The
most
efficient
way
to
diagnose
the
Bosch
OBD
II
sys-
tem
is
by
using
a
specialized
scan
tool
.
The
OBD
II
system
is
capable
of
storing
hundreds
of
faults,
making
diagnostics
with
a
scan
tool
the
only
viable
method
.
Therefore,
system
diag-
nostics
is
not
covered
here
.
Fi
31
.
Remove
to
en
ine
covers
b
in
out
caPs
and
removin
NOTE-
nuts
(A)
9
.
P
g
y
Pry
g
g
"
The
OBD
11
fault
memory
(including
an
iiluminated
Note
14
L-te
at
cover
edge
(arrows)
.
Check
Engine
light)
can
only
be
reset
using
the
spe-
cial
scan
tool
.
Removing
the
connector
from
the
ECM
2
.
Remove
two
hold
down
nuts
from
fuel
injector
wiring
or
disconnecting
the
battery
will
not
arase
the
fault
duct
.
Pry
back
injector
connector
retainers
and
lift
off
memory
.
wiring
duct
.
"
The
16-pin
OBD
Il
diagnostic
connector
is
located
on
the
lower
left
dash
panel
.
Refer
to
Fig
.
1
.
3
.
Disconnect
intake
air
bootfrom
throttle
housing
.
Where
applicable
disconnect
accelerator
cable
and
cruise
"
BMW
special
scan
tool
ora
`generic"OBD
II
scan
tool
control
cable
from
their
brackets
.
must
be
used
to
access
DTCs
.
4
.
Unbolt
intake
manifold
and
move
it
out
of
way
enough
to
access
idle
speed
control
valva
.
"
Tablak
lists
engine
control
module
(ECM)
pinouts
for
the
DMEM5
.2
system
BOSCH
DME
M5
.
2
COMPONENT
REPLACEMENT