1998 BMW M3 spark plugs

116-
6



CYLINDER
HEAD
AND
VALVETRAIN

9
.
Camshaft
installation
is
reverse
of
removal,noting
the

following
:

"
Prior
to
installation,
check
al¡
components
for
wear
as
described
below
under
Cylinder
Head
and
Val-

vetrain
Reconditioning
.

"
Crankshaft
must
be
at
least
45°
away
from
MC
before

installing
camshafts
to
cylinder
head
.

"
Lubricate
camshafts
prior
to
installation
.
"
Insta¡¡
camshafts
into
cylinder
head
with
lobes
for
cyl-
inder
no
.
1
pointing
up
and
towards
each
other
.
See
Fig
.
8
.

"
After
installing
camshaft(s),
observe
specified
waiting

time
for
hydraulic
cam
followers
to
fully
compress
be-

fore
bringing
crankshaft
back
to
TDC
.

Fig
.
8
.



Camshaft
correctly
positioned
for
reassembly
so
thatcylinder
no
.
1
lobes
(arrows)
face
each
other
.

Tightening
Torques

"
Camshaft
bearing
caps
to
cylinder
head
(M7)
.
..
...
..
.
....
15
Nm
(11
ft-Ib)
"
Cylinder
head
cover
to
cylinder
head
(M6)
..
.
..........
10
Nm
(89
in-lb)

"
Primary
timing
chaintensioner
to
cylinder
head-see
117
Camshaft
Timing
Chain
"
Spark
plugs
(M12)
.............
.
.
23
Nm
(17
ft-Ib)

"
Timing
chain
sprocket
to
camshaft
flange
(M6)-see
117
Camshaft
Timing
Chain

CYLINDER
HEAD,
DISASSEMBLYAND
ASSEMBLY

Valves,
removing
and
installing

1
.
Remove
cylinder
head
as
described
in
113
Cylinder

HeadRemoval
and
Installation
.
Remove
exhaust

manifold(s)
.

2
.
Remove
camshafts
using
special
tools
as
descríbed

earlier
.

3
.
On
M42
and
al¡
6-cylinder
engines
:
Remove
camshaft

carriers
by
pulling
them
straight
up
off
mounting
studs
.

CAUTION-

"
Do
not
let
the
hydraulic
cam
followers
fa¡¡
out
as
the
camshaft
carrier
is
removed
.
Special
suction
cupsare
available
from
BMW
to
hold
the
hydrau-
lic
cam
followers
in
place
during
carrier
removal
.
Camshaft
installation
waiting
times

"
at
or
above
68°F
(20
0
C)
....
..
.
..
......
10
minutes

"
50-68°F
(10-20°C)
...
.
..
....
.
..
......
30
minutes

"
32-50°F
(0-10°C)
....
.
..
....
.
..
......
75
minutes
4
.
On
M44
engines
:
Remove
all
hydraulic
valve
adjusters
.
See
Hydraulicvalve
adjusters,
checking
and
re-
"
Reinstall
timing
chainsprockets
and
tensioner
as
spe-



placing
(M44
engine),
later
in
this
section
.
cifically
described
in
117
Camshaft
Timing
Chain
.
"
Waít
at
least
10
minutes
before
cranking
engine
over



CAUTION-
withstarter
motor
for
the
first
time
.



Hydraulic
valve
adjusters
should
be
stored
in
an
upright
position
.
lf
necessary,
use
amagnetic
tool
to
aid
in
removal
of
the
adjusters
.

"
Hydraulic
cam
followers
shouldbe
stored
in
an
upright
position
.

5
.
Remove
valves
using
a
valve
spring
compressor
.

NOTE-

"
The
M44
cylinder
head
has
recessed
valve
stems
.
This
requires
the
use
of
a
special
valve
spring
com-
pressor
tool
.

"
Label
each
valve
assembly
as
it
is
removed
so
it
can
be
installed
in
its
original
position
.

6
.
Remove
and
discard
valve
stem
oil
seals
from
valve
guides
.
See
Valve
stem
oil
seals
later
in
this
section
.

7
.
Valve
installation
is
reverse
of
removal
.

"
Reinstall
exhaust
manifold(s)
with
new
gaskets
.
Use
Molycote
HSC'
5
or
equivalent
anti-seize
thread
com-
pound
on
fasteners
.

Tightening
Torque

"
Exhaust
manifold
to
cylinder
head
M7
............
..
...
....
.
...
..
20
Nm
(15
ft-Ib)

116-
8



CYLINDER
HEAD
AND
VALVETRAIN

0012502

Fig
.
10
.
Location
of
camshaft
oil
sprayer
tube
sea¡
in
M44
cylinder
head
(arrow)
.

Hydraulic
valve
adjusters,

checking
and
replacing
(M44
engine)

The
M44
engine
uses
hydraulic
valveadjusters
(HVA)
to
keep
valve
clearances
within
a
limited
working
range
.
See
Fig
.
11
.
HVAs
are
sealed
units
and
require
no
maintenance
.

1
.
Camshafts
2
.
Rocker
arms
3
.
Hydraulic
valve
adjusters
(HVA)
4
.
Valve
and
conical
valve
spring

Fig
.
11
.
Cutaway
view
of
M44
cylinder
head
.

Under
some
circumstances,
such
as
a
cold
start,
thehy-
draulic
units
may
become
noisy
.
Hydraulic
valve
adjusternoise
is
usually
ahigh-pitched
tapping
or
chattering
noise
.
In
most
instances,
this
is
consídered
normal
aslong
as
the
noise
goes
away
in
a
few
minutes
(maximum20
minutes)
.
If
thenoise
does
not
go
away,
either
the
hydraulic
unit
is
faulty
orthe
oil
pressure
tothe
adjuster(s)
is
low
.

CYLINDER
HEAD
AND
VALVETRAIN,
RECONDITIONING

NOTE-

8efore
checking
valveadjusters,
make
sure
engine
oil
is
fresh
and
at
proper
level
.

1
.
Run
engine
until
it
reaches
normal
operating
tempera-

ture
.

2
.
Turn
engine
off
and
remove
top
engine
cover,
spark

plugs,
and
cylinder
head
cover
.
See
113
Cylinder
Head
Removal
and
Installation
.

3
.
Use
a
plastic
or
wooden
stick
to
press
down
on
top
of

rocker
armend
(side
away
from
camshaft)
.
If
any
play
can
be
detected,the
HVA
is
faulty
and
should
be
re-

placed
.

NOTE-

When
checking
the
HVA,
make
sure
the
camshaft
lobe
is
facing
upso
that
there
is
no
valve
spring
pressure
on
the
adjuster
.

4
.
To
remove
an
HVA,
turn
engine
over
until
camshaft
lobe

points
straight
up
.
Using
BMW
special
tool
no
.
11
5
130,
depress
valvespring
and
remove
rocker
arm
from
under
camshaft
.
See
Fig
.
12
.

Fig
.
12
.
BMW
special
tool
no
.
115
130
(arrow)
being
used
to
depress
valve
stem
to
remove
rocker
arm
.

WARNING
-

Removed
rocker
armsmustbe
reinstalled
in
the
same
locations
.

Valves

Valve
specifications
are
listed
in
Table
d
.
Remove
carbon

deposits
from
thevalves
using
a
wire
brush
or
wire
wheel
.

Specification



M42
engine



M42IM44
engines



M50
engine



M50,
M52
engines



S50
USIS52
US
(1992)



(1993-1998)



(1992)



(1993-1998)



I
engine
(1995-1998)

Valve
head
dia
.
Intake



133
.0
mm
(1
.299
in)



133
.0
mm
(1
.299
in)



33
.0
mm
(1
.299
in)



33
.0
mm
(1
.299
in)



130
.0
mm
(1
.181
in)
Exhaust



30
.5
mm
(1
.201
in)



30
.5
mm
(1
.201
in)



30
.5
mm
(1
.201
in)



~
30
.5
mm
(1
.201
in)



27
.0
mm
(1
.063
in)

Valve
stem
dia
.
Standard
Intake



6
.975-0
.015
mm



5
.975-0
.015
mm



6
.975-0
.015
mm



5
.975-0
.015
mm



5
.975-0015
mm
(0
.2746-00006
in)



(0
.2352-00006
in)



(0
.2746-00006
in)



(0
.2352-00006
in)



(0
.2352
-
00006
in)
Exhaust



6
.960-0015
mm



5
.960-0
.015
mm



6
.960
--0
.015
mm



5
.960
-0
.015
mm



5
.960-0
.015
mm
(0
.2740-00006
in)



(0
.2345-0
.0006
in)



(0
.2740--0
.0006
in)



(0
.2345-0
.0006
in)



(0
.2345-0
.0006
in)

Intake



7
.075-0
.015
mm



6
.075-0
.015
mm



7
.075-0
.015
mm



6
.075-0
.015
mm



6
.075-0
.015
mm
(0
.2785-00006
in)



(0
.2392-0
.0006
in)



(0
.2785-00006
in)



(0
.2392
-
00006
in)



(0
.2392-00006
in)
Exhaust



7
.060-0015
mm



6
.060-0015
mm



7
.060-0
.015
mm



6
.060-0015
mm



6
.060-0015
mm
(0
.
2779-0
.0006
in)



(0
.2386-00006
in)



(0
.2779-00006
in)



(0
.2386-00006
in)



(0
.2386-00006
in)

Oversize
2
Intake



7
.175-0
.015
mm



6
.175-0
.015
mm



7
.175-0
.015
mm



6
.175-0
.015
mm



6
.175-0
.015
mm
(0
.2825-00006
in)



(0
.2431-00006
in)



(0
.2825-00006
in)



(0
.2431--0
.0006
in)



(0
.2431-00006
in)
Exhaust



7
.160-0015
mm



6
.160-0015
mm



7
.160-0
.015
mm



6
.160-0015
mm



6
.160-0-015
mm
(0
.2819
-
00006
i
n
)



(0
.2425-00006
in)



(0
.2819-00006
in)



(0
.2425-00006
in)



(0
.2425-00006
in)

Valves,
leak
test
NOTE-

BMW
speclal
tools
are
available
to
remove
the
valve
To
test
thevalves
for
leakage,
the
camshafts
and
camshaft



stem
oil
seals
.
As
an
alternative,
standard
valvesea¡

carriers
(where
applicable)
should
first
be
removed
.
Instali
the



removal
tools
are
available
from
most
automotive
parts

valve
assemblies
and
the
spark
plugs
in
each
cylinder
.
Place



stores
.
See
Flg
.
17
.

the
cylinder
head
on
a
workbench
with
the
combustion
cham-

ber
facing
upward
.
Fill
each
combustion
chamber
with
a
thin

non-flammable
liquid,
suchas
a
parts
cleaning
fluid
.
After
fif-

teenminutes,
check
the
leve¡
of
the
fluid
.
If
the
fluid
level
in
any

cylinder
drops,
thatcylinder
is
not
sealing
properly
.

Valve
Stem
Oil
Seals

The
purpose
of
the
valve
stem
oil
sea¡
is
to
prevent
excess

oil
from
entering
the
combustion
chamber
.
The
sign
offautty

valve
stem
oil
seals
is
excessive
oil
consumption
and
smoke

from
the
exhaust
immediately
after
starting
and
during
decel-

erat¡on

NOTE-

Valve
stem
oil
seals
should
not
be
reused
.
ff
valves
are

removed,
new
valve
stem
oil
seals
should
be
installed
.

Valve
stem
oil
sea¡
replacement
requires
that
the
cylinder

head
be
disassembled
and
thevalves
removed
as
described

above
under
Valves,
removing
and
installing
.

CYLINDER
HEAD
AND
VALVETRAIN



116-
11

Table
d
.
Valve
Specifications

Fig
.
17
.
Valve
stem
oil
sea¡
being
removed
from
valve
guide
.

Lubricate
the
new
seals
and
insta¡]
them
using
hand
pres-

sure
only
.
Be
sure
to
install
the
valve
spring
seat(s)
before
in-

stalling
the
sea¡
.

CYLINDER
HEAD
AND
VALVETRAIN,
RECONDITIONING

117-2



CAMSHAFT
TIMING
CHAIN

CAMSHAFT
TIMING
CHAIN,

4-CYLINDER

Special
BMW
service
tools
are
needed
for
timing
chain
re-
moval
and
installation
procedures
.
The
special
tools
assure

proper
timing
of
the
valvetrain
.
Precíse
marks
to
setthe
timing

on
the
camshafts
are
not
provided
for
reassembly
.
Read
the

procedures
through
before
beginning
the
job
.

CAUTION-

lf
the
camshaftsare
not
properly
timed,
the
pis-
tons
can
contact
thevalves
.

Camshaft
timing
chain,
removing

(4-cylinder
engines)
U0119-

Fig
.
3
.



Upper
timing
chain
covermounting
bolts(arrows)
.
Thermo-
1
.
Disconnect
negative
(-)cablefrom
battery
.



stat
housing
shown
removed
.
Cylinder
ídentification
sensor
(A)
also
shown
.

CAUTION-

Prior
to
disconnecting
the
battery,
read
the
battery
disconnection
cautions
given
at
the
front
of
this
manual
on
page
viii
.

2
.
Drain
engine
coolant
.
Drain
engine
block
byremoving
block
drain
.
Remove
radiator
cooling
fan
shroud
and
cooling
fan
.
See
170
Radiator
and
Cooling
System
..

WARNING
-

Allow
the
engine
to
cool
before
openingor
draining
the
cooling
system
.

CA
UTION-

On
cars
with
viscous-type
fan
clutch,
fan
has
left
hand
threads
.

NOTE-

The
block
drain
plug
is
located
on
the
exhaust
sideof
the
engine,
below
cylinder
no
.
4
.

3
.
Remove
cylinder
head
cover
.
See
113
Cylinder
HeadRemoval
and
Installation
.

NOTE-

Make
note
of
the
arrangement
of
the
rubber
insulators
when
removing
the
cylinder
head
cover
mounting
belts
.

4
.
Loosen
sparkplugs
.
See
120
Ignition
System
.

5
.
Disconnect
coolant
hoses
from
thermostat
housingon
front
of
cylinder
head
.
Unbolt
thermostat
housing
from
cylinder
head
.

6
.
Remove
cylinder
identification
sensor
from
upper
tim-
ing
chain
cover
.
Remove
upper
timing
chain
cover
.
See
Fig
.
3
.

CAMSHAFT
TIMING
CHAIN,
4-CYLINDER

7
.
Set
engine
to
approximate
TDC
by
rotating
in
normal
operating
direction
until
camshaft
lobes
at
cylinder
no
.

1
are
facing
up
and
toward
each
other
.
See
Fig
.
4
.

0011998
Fig
.
4
.



Engine
set
to
approximate
TDC
.
Cylinder
no
.
1
camshaft
lobes
face
in
and
sprocket
arrows
point
up
(arrows)
.

8
.
Remove
air
conditioning
drive
belt
.
Loosenand
push
aside
air
conditioning
compressor
.
Remove
air
condi-
tioning
compressor
mounting
bracket
.
See
640
Heat-
ing
and
Air
Conditioning
.

9
.
Remove
engine
drive
belts
and
coolant
pump
pulley
.
See
020
Maintenance
Program
.

10
.
Secure
crankshaft
vibration
damper
to
prevent
crank-
shaft
from
turning
.
Using
a
socket,
loosen
vibration
damper
hub
center
bolt
.

Camshaft
timing
chains,
removing

(6-cylinder
engines)

1
.
Disconnect
negative
(-)
cable
from
battery
.

CA
UTION-

Disconnecting
the
battery
may
erase
fault
codes)
stored
in
control
module
memory
.
Check
for
fault
codes
using
special
BMW
diagnostic
equipment
.

2
.
Drain
engine
coolant
.
Drain
engine
block
by
removing

block
drain
.
Remove
radiator
cooling
fan
shroud
and

cooling
fan
.
See170
Radiator
and
Cooling
System
.
.

WARNING
-

Allow
the
engine
to
cool
before
openingor
draining
the
system
.

CAUTION-

Radiator
fan
has
left
hand
threads
.

NOTE-

The
block
drain
plug
is
located
on
the
exhaust
side
of
the
engine,
below
cylinder
no
.
4
.

3
.
Drain
engine
oíl
andremove
oil
pan
.
See
119
Lubrica-

tion
System
.

4
.
Remove
alternator
cooling
duct
.

5
.
Remove
two
large
coolant
hoses
from
thermostat

housing
.
Remove
engine
lifting
bracket
and
thermostat

housing
from
front
of
cylinder
head
.

6
.
Loosen
bolts
for
coolant
pump
pulley
.
Then
remove

drive
belts
for
alternator
andA/C
compressor
.
See
020

Maintenance
Program
.
Remove
coolant
pump
pulley
.

Fig
.
16
.

NOTE-

OnM50
engines
with
a
two-roller
drive
belt
tensioner,

remove
the
upper
rollerto
access
thetensioner
mount-
ing
bolts
.

NOTE-

Make
note
of
the
arrangement
of
the
rubber
insulators

when
removing
the
cylinder
head
cover
mounting
bolts
.

CAMSHAFT
TIMING
CHAIN



117-
7

Fig
.
16
.
Drive
belt
tensioner
mounting
bolts
(arrows)
.

B11055

7
.
Remove
drive
belt
tensioner
from
front
of
engine
.
See



Fig
.
17
.
1992-1995
M50
engine
speed
sensor
on
timing
cover
(ar-
row)
.

10
.
Unclip
andremove
baffle
cover
from
above
intake
cam-

shaft
.
See
Fig
.
18
.

11
.
On
1992
engines
:
Remove
upper
timing
chain
cover

from
front
of
cylinder
head
.
See
Fig
.
19
.

8
.
Remove
engine
speed
sensor
from
lower
timing
chain



12
.
Loosen
spark
plugs
.
See
120
Ignition
System
.

cover,
if
applicable
.
See
Fig
.
17
.

13
.
Set
engine
to
approximate
TDC
by
rotating
in
normal

9
.
Remove
cylinder
head
cover
.
See
113
Cylinder
Head



operating
direction
until
camshaft
lobes
at
cylinder
no
.

Removal
and
Installatíon
.



1
are
facing
each
other
.
See
Fig
.
20
.

14
.
Set
engine
to
TDC
by
aligning
"0/T'
mark
(0°TDC)on

front
vibration
damper
with
cast
bosson
lower
timing

chain
cover
.
See
Fig
.
21
.

15
.
Remove
vibration
damper
mounting
bolts
and
remove

vibration
damper
and
pulley
.
See
Fig
.
22
.

CAMSHAFT
TIMING
CHAINS,
6-CYLINDER

120-2



IGNITION
SYSTEM

Fig
.1
.



Ignition
characteristic
map
.

Disabling
Ignition
System

WARNING
-

The
ignition
system
is
a
high-energy
system
operat-
ing
in
a
dangerous
voltage
range
that
couldprove
to
be
fatal
if
exposed
terminals
or
live
parts
are
con-
tacted
.
Use
extreme
caution
when
working
on
a
car
with
the
ignition
on
or
the
engine
running
.

The
ignition
system
operates
in
a
lethal
voltage
range
and
should
therefore
be
disabied
any
time
senrice
or
repair
work
is
being
doneon
the
engine
that
requires
the
ignition
to
be
switched
on
.

The
engine
management
system
can
be
disabled
byremov-
ingthe
main
relay
.
The
relay
is
located
in
the
power
distribution
box
in
the
left
rear
of
the
engine
compartment
.
See
Fig
.
2
.

0013134
Fig
.
2
.



Maínsystem
relay
(arrow)
in
power
distribution
box
(left
rear
of
engine
compartment)
.

GENERAL

WARNING
-

"
Do
not
touch
or
disconnect
any
of
the
high
ten-
sion
cables
at
the
cotls
orspark
plugs
while
the
engine
ts
running
orbeingcranked
by
the
starter
.
Fatalvoltages
are
present
.

"
Before
operating
the
starter
without
starting
the
engine
(for
example
when
making
a
compression
test)
always
disable
the
ignition
.

CAUTION-

"
Prior
to
disconnecting
the
battery,
read
the
bat-tery
disconnection
cautions
gtven
at
the
front
of
thts
manual
on
page
viti
.

"
Do
not
attempt
to
disable
the
ignition
by
either
re-
moving
the
cotl
from
the
spark
plugs
(6-cylinder
engines)
or
disconnecting
the
coll
wires
from
the
plugs
(4-cylinder
engines)
.

"
Connect
or
disconnect
ignition
system
wires,
multiple
connectors,
and
ignition
test
equipment
leads
only
while
the
ignitionis
off
.
Switch
multtm-
eter
functions
or
measurement
ranges
onty
with
the
test
probes
disconnected
.

"
Do
not
disconnect
the
battery
while
the
engine
ts
running
.

"
Many
of
the
tests
of
ignition
system
components
require
the
use
of
high-impedance
test
equip-
ment
to
prevent
damage
to
the
electrical
compo-
nents
.
A
high
impedance
digital
multimeter
should
be
used
for
all
voltage
and
resistance
tests
.
AnLED
test
light
shouldbe
used
in
place
of
an
incandescent-type
test
lamp
.

"In
general,
make
test
connections
only
as
speci-fied
by
BMW,
as
described
inthis
manual,
or
as
described
by
the
instrumenta
manufacturer
.

IGNITION
SYSTEM
DIAGNOSTICS



IGNITION
SYSTEM
SERVICE

Poor
driveability
may
have
a
variety
of
causes
.
The
fault



On
4-cylinder
engines,
an
ignition
coil
pack
is
mounted
to

may
lie
with
the
ignition
system,
the
fuel
system,
parts
of
the



the
passenger
side
strut
tower
in
the
engine
compartment
.

emission
control
system,
or
a
combination
of
the
three
.
Be-



The
coil
pack
integrates
4
individual
coils
.

cause
of
these
interrelated
functions
and
their
effects
oneach

other,
it
is
often
difficult
to
know
where
to
begin
looking
for



On
6-cylinder
engines,
an
ignition
coil
is
located
directly

problems
.



above
each
spark
plug
.

For
this
reason,
effective
troubleshooting
should
alwaysbe-

gin
with
an
interrogation
of
the
On-Board
Diagnostic
(OBD)

system
.
The
OBD
system
detects
certain
emissions-related

engine
management
malfunctions
.
When
faults
are
detected,

the
OBD
system
stores
a
Diagnostic
Trouble
Code
(DTC)
in

the
system
ECM
.
In
addition,
the
Check
Enginewarning
light

will
come
on
if
an
emissions-related
fault
is
detected
.

Two
generations
of
OBD
areusedon
the
cars
coveredby

this
manual
.
See
100
Engine-General
for
OBD
information
.

On-Board
Diagnostics

"
1992-1995
models
............
...
.
..
...



OBD
I

"
1996
and
later
models
.........
.......
..
OBD
II

NOTE-

"
On
carswith
OBD
ti,
specialized
OBD
11
scan
tool

equipment
mustbeused
to
access
DTCs,
either
using

the
BMW
special
tool
or
a
`generic"
OBD
11
scan
tool
.

"
The
OBD
11
fault
memory
(including
an
illuminated

Check
Engine
light)
can
only
be
reset
using
the
spe-

cial
scan
tool
.
Removing
the
connector
from
the
ECM

or
dísconnecting
the
battery
will
not
erase
the
fault

memory
.

Basic
Troubleshooting
Principies

An
engine
that
starts
and
runs
indicates
the
ignition
system

is
fundamentally
working-delivering
voltage
toat
least
some

of
the
sparkplugs
.
A
hard-starting
or
poor-running
engine,

however,
may
indicate
ignition
coil
problems,
cracked
or
dete-

riorated
spark
plug
wires
(4-cylinder
engines
only),
and
worn

or
fouled
spark
plugs
.

WARNING
-

Inefficient
combustion
(richair/fuel
mixture)
can

cause
the
catalytic
converter
to
overheat
and
plug
.

An
overheated
catalytic
converter
can
also
bea
tire

hazard
.

Checking
for
Spark

IGNITION
SYSTEM



120-
3

WARNING
-

If
a
spark
test
is
done
incorrectly,
damage
to
theen-
gine
control
module
(ECM)
or
the
ignitioncoil(s)
may
result
.

Checking
for
spark
is
difficult
onengines
with
distributorless

ignition
systems
.

Try
Rmovng
the
plugs
and
inspecting
for
differences
be-

tween
them
.
A
poor-firing
plug
may
be
wet
with
fuel
and/or

black
and
sooty,
butnot
always
.
If
a
coil
is
not
operating,
the

engine
management
system
will
electrically
disable
the
fuel
injectorto
that
cylinder
.
The
key
is
to
look
for
differences
be-

tween
cylinders
.

Ignition
coil,
testing
and
replacing

(4-cylinder
engine)

1.
Disconnect
mainharness
connector
from
coils
:

"
On
M42
engine,
remove
plastic
covering
from
coils
and

disconnect
individual
harness
connectors
.

"
On
M44
engine,
disconnect
main
harness
connectorat

end
of
coil
pack
.
See
Fig
.
3
.

Fig
.
3
.



Ignition
coil
pack
for
M44
engine
(arrow)
.
Coil
harness
con-

nector
shown
at1
.

IGNITION
SYSTEM
SERVICE

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
.