1994 BMW M3 fuel cap

110-2



ENGINE
REMOVAL
AND
INSTALLATION

8
.
Drain
engine
coolant
andremove
coolant
hoses
at-



10
.
Remove
radiator
cooling
fan
and
radiator
as
described

tached
to
cylinder
head
.



in
170
Radiator
and
Cooling
System
.

"
Drain
radiator
and
engine
block
.
See
170
Radiator

and
Cooling
System
.



NOTE-

"
Disconnect
hoses
from
thermostat
housing
at
front
of



Some
late
4-cylinder
modelsuse
an
electric
prímary
cylinder
head
.



cooling
fan
.
"
Disconnect
heater
hoses
at
rear
of
engine
.
See
Fig
.
2
.

CAUTION-

NOTE-



On
cars
with
viscous-type
cooling
fans,
the
radia-

"
The
block
drain
plug
is
located
on
the
exhaust
side
to-



tor
fan
has
left
hand
threads
.

wards
rear
of
engine
.

"
Remove
small
plastic
lock
clíp
to
pull
radiator
drain



11
.
Remove
upper
intake
manifold,
unfasten
cable
duct

plug
out
completely
.



from
lower
intake
manifold,
crankcase
vent
valve
hose

(M44
engine
only)

0012687

Fig
.
2
.



Coolant
hoses
at
heater
valve
and
heatercore
to
be
discon-
nected
(arrows)
.

9
.
Remove
air
shroud
from
top
of
radiator
.
See
Fig
.
3
.

ENGINE
REMOVAL
AND
INSTALLATION

12
.
Disconnect
fuel
supply
and
fuel
return
lines,
main
en-

gine
electrical
connectors,
and
lower
intake
manifold
as

described
in
113
Cylinder
HeadRemoval
and
Instal-

lation
.
See
Fig
.
4
.

0012504

Fig
.
4
.



Crankcase
ventvalve
(A)
on
top
of
lower
intake
manifoldof
M44
engine
.
Fueldelivery
and
retum
lines
shown
at
B
.
Engine
harness
and
sensor
connectors
shown
at
C
.

WARNING
-

"
Fuel
may
be
expelled
under
pressure
.
Do
not
smoke
orworknear
heaters
or
other
fire
haz-
ards
.
Keep
a
fire
extinguisher
handy
.
Before
dis-
connecting
fuel
hoses,
wrap
a
cloth
around
fuel
hoses
to
absorb
any
leaking
fuel
.
Plug
all
open
fuel
lines
.

"
Always
unscrew
the
fuel
tank
cap
to
release
pres-
sure
in
the
tank
before
working
on
the
tank
or
lines
.

CAUTION-
0013137



I
Stuff
clean
rags
into
the
open
intake
ports
topre-
Fig
.
3
.



Front
air
shroud
mounting
screws
(arrows)
.



vent
any
parts
from
falling
into
the
engine
intake
.

13
.
Disconnect
vacuum
hose
from
brake
booster
on
bulk-
head
.
Cover
bothhole
in
booster
and
plug
hose
end
.

11
.
Draín
engine
coolant
and
Rmove
coolant
hoses
at-
tached
to
cylinder
head
.

"
Drain
engine
block
byremoving
block
drain
.
"
Disconnect
hoses
from
thermostat
housing
in
front
of
cylinder
head
.

"
Disconnect
heater
hoses
at
rear
of
engine
.
See
Fig
.
9
.
"
Drain
radiator
by
removingthreaded
plastic
plug
from
lower
left
comer
.

NOTE-

"
The
block
drain
plug
is
located
oh
the
exhaust
side
to-
wards
rear
ofengine
.

"
Remove
small
plastic
lock
clipto
pulíradiator
draín
plug
out
completely
.

NOTE-

CAUTION-

Radiatorfan
has
left
hand
threads
.

ENGINE
REMOVAL
AND
INSTALLATION



110-
5

Fig
.
9
.



Coolant
hoses
at
heater
valve
and
heater
core
to
be
discon-
nected
(arrows)
.

12
.
Remove
radiator
cooling
fan
and
radiator
as
described
in
170
Radiator
and
Cooling
System
.

13
.
Label
and
disconnectcoolant
hoses,
cables,
and
har-
ness
connectors
from
throttle
housing
.
See
Fig
.
10
.

14
.
Working
atrearof
intake
manifold,
label
and
then
re-
move
fuel
supply
and
fuel
retum
lines
.
Disconnect
fuel
lines
from
support
bracket
on
manifold
.
See
Fig
.
11
.

uu12ivu
Fig
.
10
.
Throttle
housing
assemblyon
M52
engine
.
Disconnect
hos-
es,
cables
and
harness
connectors
at
and
around
housing
.

0012699

Fig
.
11
.
Special
fuelline
fitting
at
fuel
rail
on
M52/S52US
engine
.
Use
BMW
special
tool
16
1
050
to
releaselocking
fittings
at
ends
offuel
lines
.

WARNING
-

"
Fuel
may
be
expelled
under
pressure
.
Do
not
smoke
or
work
near
heaters
or
other
fire
haz-ards
.
Keep
a
fire
extinguísher
handy
.
Before
dis-
connecting
fuel
hoses,
wrapa
cloth
around
fuel
hoses
to
absorb
any
leaking
fuel
.
Plug
all
oyen
fuel
fines
.

"
Always
unscrew
the
fuel
tank
cap
to
release
pres-
sure
ín
the
tank
before
working
on
the
tank
or
lines
.

OnM52
and
S52US
engines,
special
fittings
are
used
to
retain
the
fuel
lines
to
the
fuel
rail
.
Use
BMW
special



16
.
Remove
intake
manifold
from
engine
byremoving
sev-
tool
no
.
161050
to
compress
the
locking
clip
insidethe



en
mounting
nuts
from
above
andtwo
mounting
bracket
end
of
the
fuel
line
fittings
to
release
the
fine
.



boits
from
below
.
See
Fig
.
12
.

15
.
Unbolt
power
steering
fluid
reservoir
from
its
mounting



CAllTION-
bracket
.
Use
stiff
wire
to
hang
reservoir
to
one
side
.
Do



Stuff
clean
rags
into
the
open
intake
ports
to
pre-
not
disconnect
fluid
fines
.



vent
any
parts
from
falling
into
the
engine
intake
.

ENGINE
REMOVAL
AND
INSTALLATION

11
.
Detach
wiring
harness
duct
at
rear
bulkhead
panel
and
pull
complete
duct
forward
and
up
to
allow
access
to
rear
of
cylinder
head
cover
.

12
.
Remove
spark
plugs
and
spark
plugwire
loom
.

"
Remove
plastic
cover
from
top
of
cylinder
head
.

"
Disconnect
spark
plug
wires
fromspark
plugs
and
re-

move
spark
plugs
.
"
Unbolt
spark
plug
cable
harness
and
heat
shield
from
right
side
of
cylinder
head
cover
and
set
aside
.

13
.
Unscrew
andremove
cylinder
head
cover
cap
screws

and
remove
cover
.
See
Fig
.
5
.

CAUTION-

Two
of
the
cover
hold-down
screws
are
under
the
spark
plug
cable
duct
.

NOTE-

Make
note
of
the
arrangement
of
cap
screws,
washers
and
rubber
grommets
holding
the
cylinder
head
cover
in
place
.

Fig
.
5
.



Cylinder
head
cover
mounting
points
(arrows)
.

Fig
.
7
.



M44
fuel
rail
air
connection
(A)
and
fuel
supply
and
return
lines
Intake
manifold,
removing



(B)
.

14
.
On
late
engines,
disconnect
injector
air
shrouding
hose

from
fitting
at
center
of
upper
intake
manifold
.



18
.
Disconnect
fuel
supply
and
return
lines
from
fuel
rail
.

15
.
Remove
upper
section
of
intake
manifold
.

"
Disconnect
ali
cables
harness
connectors
from
throttle

housing
and
intake
manifold
.

"
Disconnect
fuel
tank
vent
hose
fromvent
valve
on
low-

er
sitie
of
manifold
.

"
Remove
manifold
support
brackets
.
See
Fig
.
6
.

"
Remove
upper-to-lower
manifold
fasteners
(1
bolt,
2

nuts)
and
separate
upper
manifold
from
lowermani-

fold
.

Note
locating
dowei
sleeves
on
lower
to
upper
manifold
mounting
studs
.
Remove
dowels
and
set
aside
.
See
Fig
.
8
.

CYLINDER
HEAD
REMOVAL
AND
INSTALLATION



113-3

0012686

Fig
.
6
.



Intake
manifold
support
brackets
and
mountinghardware
.
Manifold
for
M44
engine
shows
.

16
.
Disconnect
oil
dipstick
tube
bracket
from
lower
manifold
section
.

17
.
On
M44
engine,
relieve
fuel
pressure
using
com-

pressed
air
(maximum
3
bar
pressure)
at
schroeder

valve
on
fuel
rail
.
Briefly
apply
air
pressure
to
force
fuel

back
intofuel
tank
.
See
Fig
.
7
.

WARNING
-

"
The
fuel
system
retains
fuel
pressure
when
the
engine
is
off
(up
to
75
psi)
.
Use
care
when
dis-
connecting
fuel
lines
.
Unscrew
the
fuel
tank
cap
to
retease
pressure
in
the
tank
.
Wrap
a
clean
shop
towel
around
the
fitting
when
loosening
.

"
Fuel
is
highly
flammable
.
When
working
around
fuel,
do
not
disconnect
any
wires
that
could
cause
electrical
sparks
.
Do
not
smoke
or
worknear
heaters
or
other
tire
hazards
.
Placea
tire
extin-
guisher
in
the
vicinity
of
the
work
area
.

19
.
Disconnect
coolant
hoses
from
vent
valve
on
lower
intake

manifold
.
Remove
crankcase
vent
valve
from
manifold
.

CYLINDER
HEAD,
4-CYLINDER

113-12



CYLINDER
HEAD
REMOVAL
AND
INSTALLATION

18
.
Working
from
underside
of
intake
manifold,
disconnect



21
.
Detach
oil
dipstick
guide
tube
from
manifold
.
Disconharness
connectors,
vent
hoses,
and
air
bypass



nectvent
hose
at
base
of
dipstick
.
hoses)
.

22
.
Remove
intake
manifold
from
engine
byremoving
sev-19
.
Working
at
rear
of
intake
manifold,
label
and
disconnect



en
mounting
nuts
from
above
andtwo
support
bracket
fuel
supply
and
fuel
return
lines
.
Remove
fuelline
hold



bolts
from
below
.
See
Fig
.
32
.
down
bracket
to
free
lines
.
See
Fig
.
31
.

NOTE-

On
M52IS52US
engines,
a
special
fitting
is
used
to
re-tain
the
fuel
fines
to
the
fuel
rail
.
Use
BMW
special
tool
no
.
16
1
050
to
expand
the
locking
clip
inside
the
end
of
the
fuellíne
fittings
.

WARNING
-

"
The
fuel
system
is
desígned
to
retan
pressure
even
wheh
the
ignition
is
off
.
When
working
with
the
fuel
system,
loosen
the
fuel
lines
slowly
toal-
low
residual
fuel
pressure
to
dissipate
gradually
.
Avoid
spraying
fuel
.

"
Fuel
is
highly
flammable
.
When
working
around
fuel,
do
not
disconnect
any
wires
that
could
cause
electrfcal
sparks
.
Do
not
smoke
orwork
near
heaters
or
other
fire
hazards
.

"
Always
unscrew
the
fuel
tank
cap
to
release
pres-
sure
in
the
tank
before
working
on
the
tank
or
lines
.

20
.
Remove
mountingscrews
and
release
wiring
harness
duct
at
rear
bulkhead
and
move
aside
.
Remove
wiring
harness
brackets
frombulkhead
.

CYLINDER
HEAD,
6-CYLINDER

Fig
.
32
.
Intake
manifoldnuts
and
support
bracket
bolts
(arrows)
.

CAUTION-

Stuff
clean
rags
into
the
open
intake
ports
topre-
001269s



vent
any
ports
from
falfing
into
the
engine
.
Fig
.
31
.
Fuel
lines
at
intake
manifold
on
M52/S52
engine
.
Use
BMW
special
tool
16
1
050
to
release
locking
fittings
at
ends
of
fuel
enes
.



1



Timing
chains,
uncoupling

23
.
Remove
VANOS
unit
from
frontof
cylinder
head
.
See
VANOS
section
in
117
Camshaft
Timing
Chain
.

24
.
Setengine
to
approximate
TDC
by
rotating
in
normal
operating
direction
until
camshaft
lobes
at
cylinder
no
.
1
are
facing
each
other
.
Arrows
on
camshaft
sprockets
should
be
pointing
up
.

NOTE-

To
confirm
that
the
crankshaft
is
set
to
the
TDC
posi-
tion,
check
that
the
OIT
mark
(0°
TDC)on
the
front
low-
er
timing
chain
cover
ís
aligned
with
the
víbration
damperSee
Fig
.
33
.

25
.
Lock
crankshaft
at
TDC
.

"
Insert
BMW
special
tool
no
.
11
2
300
through
transmis-
sion
bellhousing
and
finto
hole
in
flywheelor
drive
plate
.
See
Fig
.
34
.

GENERAL
.
........
.
...........
.
.
.
.
.
.
.
120-1



Camshaft
Position
(CMP)
Sensor
....
.
.
.
...
120-6

Disabling
Ignition
System
.
.
.
.
.....
.
.
.
.
.
.
.
120-2



Camshaft
position
(CMP)
sensor,
replacing

Warnings
and
Cautions
.
.
.
.
.
.
.....
.
.
.
.
.
.
.
120-2



(4-cylinder
engine)
..
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
...
120-6

Camshaft
position
(CMP)
sensor,
replacing

IGNITION
SYSTEM
DIAGNOSTICS
.
.
.
.
.
.
120-3



(6-cylinder
engine)
..
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
120-7
Basic
Troubleshooting
Principles
...
.
.
.
.
.
.
.
120-3



Knock
sensors,
replacing
.
.
...
.
.
.
.
.
.
.
.
.
.
.
.
120-7

Ignition
Firing
Order
.....
.
...
.
.
.
.....
.
.
.
.120-7

IGNITION
SYSTEM
SERVICE
.
.........
.
120-3

Checking
for
Spark
..
.
.
.
.
.
.
.
.
.
.......
.
.
.
120-3

Ignition
coil,
testing
and
replacing

(4-cylinder
engine)
.
.
.
.
.
.
.
.
.
.
.........
.
120-3

Ignition
coil,
testing
and
replacing

(6-cylinder
engine)
.........
.
..........
120-4

Crankshaft
Positionlrpm
Sensor
.......
.
...
120-5

Crankshaft
position/rpm
sensor,
testing
and

replacing
(front
mounted)
.........
.
.
.
.
.
.
120-6

Crankshaft
position/rpm
sensor,replacing

(rear
mounted)
.....
.
.....
.
.....
.
.
.
.
.
.
120-6

GENERAL



Troubleshooting
and
testing
of
the
engine
management

system
should
be
carried
out
using
the
BMW
specialized
ser

This
repair
group
covers
repair
andcomponent
replace-



vice
tester
(scan
tool)
.

ment
information
for
the
ignition
system
.
All
engines
use
a
distributorless
ignition
system
with
indívid-

ual
ignitioncoils
for
each
cylinder
.
There
is
no
distributor
cap

NOTE-



or
ignition
rotor
.
Each
coil
can
be
selectively
controlled
by
the

"
Spark
plug
replacement
is
covered
in
020
Mainte-



engine
control
module
on
a
cylinder-by-cylinder
basis
.
On
later

nance
Program
.



systems,
knock
sensors
are
used
to
monitor
and
control
igni-

"
For
fuel
related
troubleshooting
and
testing,
see
130



tion
knock
(ping)
and
adjusttiming
accordingly
.

Fuel
lnjection
.
Ignition
timing
is
electronically
controlled
and
not
adjust-

All
engines
covered
by
this
manual
use
an
advanced
en-



able
.
The
engine
control
module
(ECM)
usesengine
load,
en-

gine
management
system
.
The
engine
management
system



gine
speed,
coolant
temperature,
and
intake
air
temperature

incorporates
on-board
diagnostics,
fuel
injection,
ignition
and



as
the
basic
inputs
for
timing
control
.
Knock
detection
is
also

other
advanced
engine
control
functions
.



an
input
to
the
control
module,
where
applicable
.

Table
a
.
Engine
Management
System
Variants

Engine
code



1
System

4-cylinder
M42
(1.8
I)



Bosch
DME
Ml
.7
M44
(1
.9
I)



Bosch
DME
M5
.2
(OBD
II)

6-cylinder
M50
1992
(2.5
I)



Bosch
DME
M8
.1
1993-1995
(2
.5
I)



Bosch
DME
M33
.1
M52
1996-1998
(2.8
I)



Siemens
MS
41
.1
(OBD
II)

1998
(2
.5
I)



Siemens
MS
41
.1
(013D
11)
S50US
(3.0
I)



Bosch
DME
M3
.3.1
S52US
(3.2
I)



Siemens
MS
41
.1
(OBD
II)

120
Ignition
System

IGNITION
SYSTEM



120-1

IGNITION
SYSTEM
SCHEMATICS
...
.
.
.
.120-7

TABLES

a
.
Engine
Management
System
Variants
......
120-1

b
.
Ignition
Coil
Resistance
(M42
engine)
......
120-4

c
.
Ignition
Coil
Resistance
(M44
engine)
......
120-4

d
.
Ignition
Coil
Resistance

(6-cylinder
engine)
..
.
.
.
.
.
.
.
.
.
.
.
.....
.
..
120-5

NOTE-

All
engines
coveredby
this
manual,
with
theexception

of
the
1992
M50,
incorporate
knocksensors
as
part
of

the
engine
management
system
.

The
initial
ignition
point
is
determined
by
the
crankshaft
po-

sition/rpm
sensor
during
cranking
.
Once
the
engine
is
run-

ning,
timing
is
continually
adjusted
based
on
operating

conditions
.
A
characteristic
ignition
map
is
shown
in
Fig
.
1
.
A

map
similar
to
the
one
shown
is
digitally
stored
in
the
engine

control
module
.

GENERAL

130-2



FUEL
INJECTION

GENERAL

This
repair
group
covers
fuel
injection
system
component

testing
and
repair
.
Special
equipment
is
necessary
for
some

of
the
procedures
given
in
this
repair
group
.
If
you
do
not
have

the
equipment
required
to
do
the
job,
it
is
recommended
that

these
repairs
be
left
to
an
authorized
BMW
dealer
.
The
BMW

dealer
is
equipped
with
sophisticated
diagnostic
test
equip-

ment
that
is
capable
of
quicklypinpointing
hard-to-find
fuel
in-

jection
problems
.

NOTE-

"
Wiring
diagrams
for
the
engine
management
system,

can
be
found
at
the
rear
of
the
manual
under
Electri-
cal
Wiring
Diagrams
.

"
For
ignition
system
repairinformation,
see120
Igni-

tion
System
.

"
For
fuel
supply
system
testing
and
repair,
see160



The
engine
control
module
(ECM)
uses
electrical
signals

Fuel
Tank
and
Fuel
Pump
.



from
the
mass
air
flow
sensor,
the
air
and
coolant
temperature

sensors,
the
crankshaft
position/rpm
sensor,
the
knock
sen

Principies
Of
Operation



sors
and
the
oxygen
sensorsas
the
primary
inputs
to
electron-

ically
control
fuel
delivery
and
ignition
timing
.

There
are
five
versions
of
engine
management
systems

usedon
the
E36
cars
.
Each
has
the
same
basic
components

and
operating
principles
.
The
most
notable
difference
is
that

1996
and
later
cars
use
a
sophisticated
OBD
II-compliant
sys-

tem
.
See
Table
a
.

Table
a
.
Engine
Management
System
Variants

Engine
code/year



1
System

4-cy1inder
M42
(1
.8
I)
1992-1995



Bosch
DME
Ml
.7
M44
(1
.91)
1996-1998



~
Bosch
DME
M5
.2
(OBD
II)

6-cylinder
M50
1992
(2.5
I)



Bosch
DME
M3
.1
1993-1995
(2.5
I)



Bosch
DME
M3
.3.1
(VANOS)
M52
1996-1998
(3281-
2
.8
I)



Siemens
MS
41
.1
(OBD
II)
1998
(3231
-
2
.5
I)



Siemens
MS
41
.1
(OBD
II)
M-Power
S50US
(M3
-
3
.01)
1995



Bosch
DME
M3
.3
.1
S52US
(M3
-
3
.21)
1997-1998



Siemens
MS
41
.1
(0131)
11)

NOTE-

-
Descriptions
and
procedures
in
the
first
partof
this
re-

pairgroup
refer
to
all
the
various
engine
management
systems
.

"
Particulars
of
each
fuel
injection
system
are
treated
in
separate
sections
in
the
second
part
of
this
repair
group
.

GENERAL

Fig
.1
.



OBD
II
diagnostic
connector
locatíon
.

The
fuel
injection
system
is
completely
electronic
in
opera-

tion
.
Air
flow
is
measured
electronically
via
a
mass
air
flow

sensor
and
additional
sensors
supply
information
about
en-

gine
operating
conditions
.
The
ECM
calculates
the
amount
of
fuel
needed
for
the
correct
air-fuel
ratio
and
actuates
the
fuel

injectors
accordingly
.
The
amount
offuel
metered
to
theen-

gine
is
determined
by
how
long
the
injectors
are
open
.

Airintake
.
Air
entering
the
engine
passes
through
a
pleat-

ed
paper
air
filter
in
the
air
cleaner
.
Intake
air
volume
or
mass

is
then
measured
bya
mass
air
flow
(MAF)
sensor
.
In
al¡
ex-

cept
the
vane
type
sensor
(DME
M1
.7),
a
reference
current
is

used
to
heat
a
thin
wireor
film
in
the
sensor
when
the
engine

is
running
.
The
current
used
to
heat
the
wire/film
is
electroni-

cally
converted
into
a
voltage
measurement
corresponding
to

the
mass
of
the
intake
air
.

Table
b
.
Mass
Air
Flow
Sensor
Variants

System



Al
r
flow
sensor
type

Bosch
DME
M1
.7



Vane
(volume
sensor)

Bosch
DME
M3
.1



Hot
wire
(mass
sensor)

Bosch
DME
M3
.3
.1



Hot
film
(mass
sensor)

Bosch
DME
M5
.2



Hot
film
(mass
sensor)

Siemens
MS
41
.1



Hot
film
(mass
sensor)

"
The
16-pin
OBD
11
diagnostic
connector
is
located
on



NOTE-

the
lower
left
dashpanel
.
See
Fig
.
1
.



On
cars
equipped
wíth
tractioncontrol,
an
additional
throttle
valve
is
controlled
by
an
electronic
throttle
actu-
ator
(motor)
.
This
valve
is
used
for
engine
speed
inter
vention
.
Repair
information
forthis
system
is
notcovered
here
due
to
the
special
electrical
testing
equip-
ment
required
to
service
it
.

The
fuel
injection
systems
used
on
the
1996
and
later
cars
covered
bythis
manual
are
OBD
II
compliant
.
This
system
is
in-
corporated
into
both
the
Bosch
M5
.2
(M44
engine)
and
the
Si-
emens
MS
41
.1
(M52/S52US
engine)
engine
management
systems
.
OBD
II
systems
use
sophisticateddiagnostic
soft-
ware
capable
of
recognizing
and
electronically
storing
hun-
dreds
of
DTCs
in
the
system
ECM
.
DTCs
can
only
be
accessed
using
special
scan
tooltest
equipment
.
The
BMW
dealer
is
equipped
with
the
specialized
OBD
II
scan
toolto
quickly
and
efficiently
locate
engine
management
problems
.
Alternately,
a
"generic"
scan
tool
can
be
used
to
access
OBD
II
fault
informa-
tion
.

NOTE-

"
At
the
time
this
manual
went
to
press,
generic
scan
tools
were
notwidely
available
for
BMW
vehicles
.
The
generic
sean
tool
is
a
specialized
toolthat
plugs
into
a
standardized
OBD
11
connector
on
1996
and
later
pas-senger
vehícles
built
for
sale
in
the
US
.

"
The
OBD
11
fault
memory
(including
an
illuminated
Check
Engine
light)
can
only
be
reset
using
the
spe-
cial
scan
tool
.
Removing
the
connector
trom
the
ECM
or
disconnecting
the
battery
will
not
erase
the
fault
memory
.

"
The
16-pin
OBD
11
diagnostic
connector
is
located
on
the
lower
left
dash
panel
.
Refer
to
Fig
.
1
.

6

1
.
Secondary
air
pump
2
.
Electric
solenoid
valve
3
.
One-way
check
valve
4
.
Intake
manifold
5
.
Exhaust
manifolds
6
.
Secondary
air
check-valve

®
G~



i

o
o



0
0
G
0000
o



,-
00

~

1111111
in

,,
0
1--

a

Fig
.
5
.



Components
of
6-cylinder
secondary
air
injection
system
.
4-
cylinder
system
is
similar
.

Secondary
AirInjection

FUEL
INJECTION



130-
5

All
OBD
II
6-cylinder
engines
are
equípped
with
asecond-
ary
air
injection
system
.
In
addition,
beginning
in
January
1997,
the
M44
engine
was
classified
as
a
TLEV
(Transitional
Low
Emission
Vehicle)
engine
and
is
also
equipped
with
sec-
ondary
air
injection
.

Typical
components
of
the
secondary
air
injection
system

are
depicted
in
Fig
.
5
.

Secondary
air
injection
usesan
electric
pump
to
pump
fresh
air
finto
the
exhaust
systemupstream
of
the
catalytic
converter
during
engine
warm-up
.
By
providing
extra
oxygen
to
the
un-
burned
fuel
in
the
exhaust,
hydrocarbons
oxidize
and
carbon

monoxide
combines
with
oxygen
to
form
carbon
dioxide
andwa-
ter
.
The
air
injection
pump
stops
within
a
specified
timed
intenral
.

4

0013120

GENERAL

130-
6



FUEL
INJECTION

Warnings
and
Cautions

For
personal
safety,
as
well
as
the
protection
of
sensitive

electronic
components,
the
following
warnings
and
cautions

should
be
adhered
to
when
working
on
the
engine
manage-

ment
system
.

GENERAL
WARNING
-

"
The
ignition
system
produces
high
voltages
that

can
be
fatal
.
Avoid
contact
with
exposed
termi-

nals
.
Use
extreme
caution
when
working
onacar
with
the
ignition
switched
on
or
the
engine
run-
ning
.

"
Do
not
touch
or
disconnect
any
high
voltage
ca-

bles
from
the
coils
or
spark
plugs
while
the
engine

is
running
or
beingcranked
by
the
starter
.

"
Connect
and
disconnect
the
DME
system
wiring
and
test
equipment
leads
only
when
the
ignition
is
switched
off
.

"
Gasoline
is
highly
flammable
and
fts
vaporsare

explosive
.
Do
not
smoke
or
work
on
a
car
near
heaters
or
other
fire
hazards
when
diagnosing
and
repalring
fuel
system
problems
.
Have
a
tire
extinguisher
avaílable
in
case
of
an
emergency
.

"
When
working
onan
open
fuel
system,
wear
suit-
able
hand
protection,
asprolonged
contact
wfth
fuel
can
cause
illnesses
and
skin
disorders
.

"
Renew
fuel
system
hoses,
clamps
and
O-rings
any
timethey
are
removed
.

"
Before
makingany
electrical
tests
that
require
the
engine
to
be
cranked
using
the
starter,
disable
the
ignition
system
as
described
in
120
Ignition
System
.

CAUTION-

"
Prior
to
disconnecting
the
battery,
read
the
bat-
tery
disconnectinn
cautions
given
at
the
front
of
this
manual
onpage
vifi
.

"
Do
not
connect
any
test
equipment
that
delivers

a
12-volt
power
supply
to
terminal
15
(+)
of
the
ig-

nitioncoil
.
The
current
flow
may
damage
the

ECM
.
In
general,
connect
test
equipment
only
as

speclfied
by
BMW,
this
manual,
or
the
equipment

maker
.

"
Only
use
a
digital
multlmeter
for
electrical
test
.

"
Only
use
an
LED
test
light
for
quick
tests
.

"
Disconnecting
the
battery
may
erase
fault

code(s)
stored
in
memory
.
Check
for
fault
codes

prior
to
disconnecting
the
battery
cables
.
ff
the

Check
Engine
light
ís
illuminated,
see100En-
gine-General
for
DME
fault
code
information
.
ff
any
other
system
faults
have
been
detected
(indi-
catedbyan
illuminated
warning
light),
see
an
au-
thorized
BMW
dealer
.
Additional
systems
with
self-diagnostic
capabilities
include,
ABS
(Anti-
lock
brakes),
SRS
(Airbags),
EML
and
ASC+T
and
AST
(Traction
Control)
.

"
Do
not
run
the
engine
wfth
any
of
the
spark
plug
wires
dlsconnected
.
Catalytic
converter
damage
may
result
.

"
Always
waitat
least
40
seconds
afterturning
off
the
ignition
before
removing
the
engine
control
module
(ECM)
connector
.
ff
the
connector
isre-
moved
before
this
time,
residual
power
in
the
sys-
tem
relay
may
damage
the
control
module
.

"
Cleanliness
is
essential
when
working
onan
open
fuel
system
.
Thoroughly
clean
fuel
line
con-
nections
and
surroundlng
areas
before
loosen-
ing
.
Avoid
moving
the
car
.
Only
fnstall
cleanparts
.

"
Fuel
system
cleaners
and
other
chemical
addi-
tives
other
than
those
specifically
recommended
by
BMW
may
damage
the
catalytic
converter,
the
oxygensensor
or
other
fuel
supply
components
.