1993 BMW 325i Rela y

Please
read
these
warnings
and
cautions

before
proceeding
with
maintenance
and
repair
work
.

WARNING-



"
Friction
materials
(such
as
brake
pads
or
shorts
or
clutchdiscs)
contain
asbestos
fibers
or
other
friction
materials
.
Do
notcreate
"
See
also
Cautionson
page
viü



dustby
grinding,
sanding,
orby
cleaning
with
compressed
air
.

"
Some
repairs
may
be
beyond
your
capability
.
If
you
lack
the



Avoid
breathing
dust
.
Breathing
any
friction
material
dust
can
lead

skills,
tools
and
equipment,
or
a
suitable
workplace
for
any
proce-



to
serious
diseases
and
may
result
in
death
.

duredescribed
in
this
manual,
we
suggestyou
leave
such
repairs



"
Batteries
give
off
explosive
hydrogen
gas
during
charging
.
to
an
authorized
BMW
dealer
service
department
or
other
quali-



Keep
sparks,
lighted
matches
and
open
flame
away
from
the
top
fied
shop
.



of
the
battery
If
hydrogen
gas
escaping
from
the
cap
vents
is

"Do
not
re-use
any
fasteners
that
are
worn
or
deformed
in
normal



ignited,
it
will
ignite
gas
trapped
in
the
cells
and
cause
the
battery

use
.
Many
fasteners
are
designed
to
be
used
only
once
and



to
explode
.

become
unreliable
and
may
fail
when
used
a
second
time
.
This



"
Connect
and
disconnect
battery
cables,
jumper
cablesora
bat-
includes,
but
is
not
limited
to,
nuts,
bolts,
washers,
self-locking
nuts
or
bolts,
circlips
and
cotterpins
.
Always
replace
these
fasteners

with
new
parts
.
"Do
not
quick-charge
the
battery
(for
boost
starting)
for
longer
"
Never
work
under
a
lifted
car
unless
it
is
solidly
supportedon



than
one
minute
.
Wait
at
least
one
minute
before
boosting
the
bat-
stands
designed
for
the
purpose
.
Do
not
support
a
car
on
cinder



tery
a
second
time
.
blocks,
hollow
tiles
or
other
props
that
may
crumble
under
contin-

uous
load
.
Never
work
under
acar
that
is
supported
solely
by
a



"Do
not
allow
battery
charging
voltage
to
exceed
16
.5
volts
.
If
the

jack
.
Never
work
under
thecar
while
the
engine
is
running
.



battery
beginsproducing
gas
or
boiling
violently,
reduce
the
charg-
ing
rate
.
Boosting
a
sulfated
battery
at
a
high
charging
rate
can
"
If
you
are
going
to
work
under
acar
on
the
ground,
make
sure



cause
an
explosion
.
that
the
ground
is
level
.
Block
the
wheels
to
keep
the
carfrom
roll-

ing
.
Disconnect
the
battery
negative
(-)
terminal
(ground
strap)to



"
The
air-conditioning
system
is
filled
with
chemical
refrigerant,

prevent
others
from
starting
thecar
while
youare
under
it
.



which
is
hazardous
.
TheA/C
system
should
be
servicedonly
by

trained
technicians
using
approved
refrigerant
recovery/recycling
"
Never
run
the
engine
unless
the
work
area
is
well
ventilated
.



equipment,
trained
in
related
safetyprecautions,
and
familiar
with
Carbon
monoxide
kills
.



regulations
governing
the
discharging
and
disposal
of
automotive

"
Finger
rings,
bracelets
and
other
jewelry
shouldbe
removed
so



chemical
refrigerants
.

tery
charger
only
with
the
ignition
switched
off,
to
prevent
sparks
.

Do
not
disconnect
the
battery
while
the
engine
is
running
.

that
theycannot
cause
electrical
shorts,
get
caught
in
running



"
Do
not
expose
any
partof
the
A/Csystem
to
high
temperatures
machinery,
or
be
crushed
by
heavy
parts
.



suchas
open
flame
.
Excessiveheat
will
increase
system
pressure

"
Tie
long
hair
behind
your
head
.
Do
not
wear
a
necktie,
a
scarf,



and
may
cause
the
system
to
burst
.

loose
clothing,
or
a
necklace
when
you
work
near
machine
tools
or



"
Some
aerosol
tire
inflators
are
highly
flammable
.
Be
extremely
running
engines
.
If
your
hair,
clothing,
or
jewelry
were
to
get
caught



cautious
when
repairing
a
tire
that
may
havebeen
inflated
using
in
the
machinery,
severe
injury
could
result
.



an
aerosol
tire
inflator
.
Keep
sparks,
open
flame
or
other
sources

"
Do
not
attempt
to
work
onyourcar
if
you
do
not
feel
well
.
You



of
ignition
away
from
the
tire
repair
area
.
Inflate
and
deflate
the
tire

increase
the
danger
of
injury
toyourself
and
others
if
you
are
tired,



at
least
four
times
before
breaking
the
bead
from
therim
.
Com-

upset
or
have
takenmedication
or
any
other
substance
that
may



Pletely
remove
the
tire
from
the
rim
beforeattempting
any
repair
.

keep
you
from
being
fully
alert
.

"
Illuminate
your
work
areaadequately
but
safety
.
Use
a
portable

safety
light
for
working
inside
or
under
thecar
.
Make
surethe
bulb

is
enclosedbya
wire
cage
.
The
hot
filament
of
an
accidentally
bro-

ken
bulb
can
ignite
spilled
fuel
or
oil
.

"
Catch
draining
fuel,
oil,
orbrake
fluid
in
suitable
containers
.
Do

not
use
food
or
beverage
containers
that
mightmislead
someone

into
drínking
from
them
.
Store
flammable
fluids
away
from
fire
haz-

ards
.
Wipe
up
spills
at
once,
but
do
not
store
the
oily
rags,
which

can
ignite
and
burn
spontaneously
.

"
Always
observe
good
workshop
practices
.
Wear
goggles
when

youoperate
machine
tools
or
work
with
battery
acid
.
Gloves
or

other
protectioeclothing
should
be
worn
whenever
thejob
requires

working
with
harmful
substances
.

"
Greases,
lubricants
and
other
automotive
chemicals
contain

toxic
substances,
many
of
which
are
absorbed
directly
through
the

skin
.
Read
the
manufacturer's
instructions
and
warnings
carefully
.

Use
hand
andeye
protection
.
Avoid
direct
skin
contact

"
Cars
covered
by
this
manual
are
equipped
with
a
supplemental

restraint
system
(SRS),
that
automatically
deploys
an
airbag(s)
in

theevent
of
a
frontal
ímpact
.
The
airbag(s)
is
inflated
byan
explo-

sive
device
.
Handled
improperly
or
without
adequate
safeguards,

can
be
accidently
activated
and
cause
serious
injury
.

"
The
ignition
system
produces
high
voltages
that
can
be
fatal
.

Avoid
contact
with
exposed
terminals
and
use
extreme
care
when

working
ona
car
with
the
engine
running
or
the
ígnition
switched
on
.

"
Place
jack
stands
only
at
locations
specified
bymanufacturer
.

The
vehicle
lifting
jacksupplied
with
the
vehicle
is
intended
for
tire

changes
only
.
A
heavy
duty
floor
jack
shouldbe
used
to
lift
vehicle

before
installing
jack
stands
.
See
010
Fundamentals
for
theDo-
.

it-Yourself
Owner
.

"
Battery
acid
(electrolyte)
can
cause
severeburns
.
Flush
contact

area
with
water,
seek
medical
attention
.

"
Aerosolcleaners
and
solvents
may
contain
hazardous
ordeadly
vapors
and
are
highly
flammable
.
Use
only
in
a
wellventilated

area
.
Do
not
use
on
hot
surfaces
(engines,
brakes,
etc
.)
.

"
Disconnect
the
battery
negative
(-)
terminal
(Ground
strap)



"
Do
not
remove
coolant
reservoir
or
radiator
cap
with
theengine

whenever
you
work
on
the
fuel
system
orthe
electrical
system
.
Do



hot
.
Danger
of
bums
and
engine
damage
.

not
smoke
or
work
near
heaters
or
other
fire
hazards
.
Keep
an

approved
fire
extinguisher
handy
.



continued
on
next
page
vii

010-
4



FUNDAMENTALS
FOR
THE
DO-ITYOURSELF
OWNER

Fig
.
3
.



BMW
supplied
jack
correctly
positioned
in
front
jacking
point
.



Most
of
the
repairs
and
maintenance
tasks
described
in
this

manual
can
be
successfully
completedby
anyone
with
basic

tools
and
abilities
.
To
prevent
getting
in
too
deep,
know
what

WARNING-



the
wholejob
requires
before
starting
.
Read
the
procedure
thor-

"
Do
not
rely
on
thetransmission
or
the
emergen-



oughly,
from
beginning
to
end,
in
order
to
know
just
what
to
ex
cybrake
to
keep
thecar
from
rolling
.
They
are



pect
and
what
parts
will
have
to
be
replaced
.

nota
substitute
for
positively
blocking
the
oppo-
site
wheel
.

"
Never
work
undera
car
that
is
supported
only
by
ajack
Use
jack
stands
that
are
properly
de-
signed
to
support
the
car
.
See
Tools
.

Working
under
car
safely

1
.
Disconnect
negative
(-)
cable
from
battery
so
that
no

one
else
can
start
thecar
.
Let
others
know
what
you
will

be
doing
.

CAUTION-

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

2
.
Raisecar
slowly
as
described
above
.

3
.
Use
at
least
two
jack
stands
to
support
thecar
.
A
jack
is
atemporary
lifting
device
and
should
not
be
used
alone
to
support
the
car
while
you
are
under
it
.
Use
jack
stands
designed
for
the
purpose
of
supporting
a
car
.
For
more
information
on
jack
stands,
see
Toolsbelow
.

WARNING
-

Do
notusewood,
concrete
blocks,
orbricks
to
sup-
port
acar
.
Woodmay
split
.
Blocks
or
bricks,
while
strong,
are
not
designed
for
that
kind
of
load,
and
may
brakkor
collapse
.

ADVICE
FOR
THE
BEGINNER

4
.
Place
jack
stands
on
firm,
solid
surface
.
If
necessary,

use
a
flat
board
or
similar
solid
object
to
provide
a
firm

footing
.

5
.
Lower
car
slowly
until
its
weight
is
fully
supportedby

jack
stands
.
Watch
to
make
sure
that
the
jack
stands
do

not
tip
orlean
as
thecar
settles
on
them
.

6
.
Observe
all
jacking
precautions
again
when
raising
car

to
remove
jack
stands
.

ADVICE
FORTHE
BEGINNER

The
tips
in
the
paragraphs
that
follow
are
general
advice
to

help
any
do-it-yourself
BMW
owner
perform
repairs
and
main-

tenance
tasks
more
easily
and
more
professionally
.

Planning
Ahead

Cleanliness

Keeping
things
organized,
neat,
and
clean
is
essential
to
do-

ing
a
good
job
.
When
working
under
the
hood,
fender
covers

will
protect
the
finish
from
scratches
and
other
damage
.
Make
sure
the
car
is
relatively
clean
so
thatdi
rt
under
the
cover
does

not
scratch
the
finish
.

Any
repair
job
will
be
less
troublesome
if
the
parts
are
clean
.

For
cleaning
old
parts,
there
are
many
solvents
and
parts

cleaners
commercially
available
.

For
cleaning
parts
priorto
assembly,
commercially
available
aerosol
cans
of
parts
cleaner
or
brake
cleaner
are
handy
to
use,
and
the
cleaner
will
evaporate
completely
.

WARNING
-

Virtually
all
solvents
used
for
cleaning
parts
are
highly
flammable,
especially
in
aerosol
form
.
Use
wíth
extreme
care
.
Do
not
smoke
.
Do
not
use
these
products
near
any
source
of
heat,
sparksor
flame
.

Let
any
solvent
orcleaning
product
dry
completely
.
Low-
pressure,
dry
compressed
air
is
helpful
if
available
.
Also,
use
only
lint-free
rags
for
cleaning
and
drying
.

Non-returnable
Parts

FUNDAMENTALS
FOR
THEDO-ITYOURSELF
OWNER
010-
7

Many
independent
repair
shops
make
a
point
of
using
genu-



Original
body
paneis
and
other
large
components
are
identi-

ine
BMW
parts,
even
though
they
may
at
times
be
more
expen-



fied
by
a
label
bearing
the
VINand
two
BMW
roundellogos
.
Re-

sive
.
Theyknow
the
value
of
doing
thejob
right
with
the
right



placement
parts
have
a
similar
label,
bearing
one
BMW
roundel

parts
.
Parts
from
other
sources
can
beas
good,
particularly
if



logo
and
the
letters
DOT-R
.
See
Fig
.
6
.
Parts
or
assemblies

manufactured
by
one
of
BMWs
original
equipment
suppliers,



bearing
the
label
arethe
engine,
transmission,
front
and
rear

but
it
is
often
difficult
to
know
.



bumpers,
front
fenders,
rear
quarter
paneis,
hood,
trunk
lid
and

doors
.
These
labels
shouldnot
be
removed
as
they
will
tear

BMW
is
constantly
updating
and
improving
their
cars,
often



apart
.

making
improvements
during
a
given
model
year
.
BMW
may

recommend
a
newer,
improved
part
as
a
replacement,
and

your
authorized
dealer's
parts
department
will
know
about
it

and
provide
it
.
The
BMW
parts
organization
is
best
equipped
to
deal
with
any
BMW
parts
needs
.

Some
parts
cannot
be
returned
for
credit,
even
if
they
arethe

wrong
parts
forthe
car
.
The
best
example
is
electrical
parts,

which
are
almost
universally
considered
non-returnable
be-



,
..

cause
they
are
so
easily
damaged
internally
.

Buy
electrícal
parts
carefully,
and
beas
sure
as
possible
that
P-
DOT~
R

a
replacement
is
needed,
especially
for
expensive
parts
such
as
electronic
control
units
.
It
may
bewise
to
let
an
authorized



B328FUN

BMW
dealeror
other
qualified
shop
confirm
your
diagnosisbe-

fore
replacing
an
expensive
part
that
cannot
be
retuned
.



Fig
.
6
.



Labels
used
to
identiy
parts
.
Original
equipment
labelwith

VIN
number
and
roundel
logos
(top)
and
replacement
part
la-

bel
with
one
roundel
logos

Information
You
Need
to
Know

Engine
.
3-Seriescars
covered
in
this
manualare
powered

Model
.
When
ordering
parts
it
is
important
that
you
know
the



by
either
a
4-or
6-cylinder
engine
.
For
information
-
on
engine

correct
model
designation
for
your
car
.
Models
covered
in
this



codes
and
engine
applications,
see100
Engine-General
.

manual
are
E36
3
Series
in
both
4-
and
6-cylinderconfigura-

tions
.



Transmission
.
The
transmissiontype
with
its
identifying

code
may
be
important
when
buying
clutch
parts,
seals,
gas

Moda¡
Year
.
This
is
not
necessarily
the
same
as
date
of



kets,
and
othertransmission-relatedparts
.
For
information
on

manufacture
or
date
of
sale
.
A
1997
model
may
havebeen



transmission
codes
and
applications,
see200
Transmission

manufactured
in
late
1996,
and
perhaps
not
sold
until
early



General
.

1997
.
It
is
still
a1997
model
.
Model
years
covered
by
this
man-

ual
are
1992
to
1998
.

SERVICE
Date
of
Manufacture
.
This
information
is
helpful
when
or-

dering
replacement
parts
or
determining
if
any
of
the
warranty



BMW
dealers
are
uniquely
qualified
to
provide
service
for
recalls
are
applicable
to
your
car
.
The
label
on
the
driver's
door



BMW
cars
.
Their
authorized
relationship
with
the
large
BMW
below
the
door
latch
will
specify
the
month
and
year
that
the
car



serviceorganization
means
that
they
are
constantly
receiving
was
built
.



new
tools
and
equipment,
together
with
the
latest
and
most
ac-

curate
repair
information
.
Vehicle
Identification
Number
(VIN)
.
This
is
a
combination

of
letters
and
numbers
that
identify
the
particular
car
.
TheVIN

appears
on
the
state
registration
document,
and
on
thecar
it-

self
.
One
location
isin
the
rear
of
the
engine
compartment,
en-

other
in
the
lower
left
comer
of
the
windshield
.

The
National
Highway
Traffic
Safety
Administration
(NHT-

SA)
requires
passenger
cars
with
a
high
theftrateto
have
the

VINmarked
on
specific
parts
of
thecar
when
manufactured
.
On

BMW
cars,
these
parts
are
identified
byan
adhesive
label
.

)WBADK00000000

0
000
0

The
BMW
dealers
service
technicians
are
highlytrained
and

very
capable
.
Unfke
most
independent
repair
shops,
autho-

rized
BMW
dealers
are
intensely
committed
tosupporting
the

BMW
product
.
They
share
the
owners
interest
in
BMW
value,

performance,
and
reliability
.
On
the
other
hand,
there
are
many

independent
shops
that
specialize
in
BMW
service
and
are
ca-

pable
of
doing
high
quality
repair
work
.
Checking
with
other

BMW
owners
for
recommendations
on
service
facilitiesis
a

good
way
to
leam
of
reputable
BMW
shops
in
yourarea
.

SERVICE

If
steam
is
coming
from
the
engine
compartment
thenthere
is



With
the
engine
and
ignition
off,
check
for
loose
or
corroded
most
likely
a
burst
coolant
hose
or
a
large
leak
in
the
cooling



battery
cables
or
wires
at
the
battery
or
thealtemator
.
Discon-
system
.
To
find
the
leak,
look
for
signs
of
coolant
leakage
on



necting,
cleaning,
and
reinstalling
corroded
wires
and
connec-
hoses,
at
hose
connections,
or
on
the
radiator
.
Let
theengine



tors
may
solve
the
problem
.
Also
check
drive
belt
tension
as
cool
thoroughly,
then
add
coolant
or
water
to
fill
the
system
and



described
in
020
Maintenance
Program
.
start
the
engine
.
If
a
great
deal
of
water
or
coolant
flows
out
of
the
hole,
then
thecarshouldnot
be
driven
until
repairs
are
made
.
lf
there
is
slight
seepage,
then
it
may
be
possible
to
drive



TOWi
ng

a
short
distance,
adding
coolant
as
needed
.
The
cars
covered
by
this
manual
should
be
towed
witha
tow
truck
using
wheel
lift
or
flat
bed
equipment
.
Do
not
tow
thecar
on
all
four
wheels
except
for
very
short
distances
to
move
it
to
a
safe
place
.
If
thered
engine
oil
pressure
warning
light
illuminates,
imme-
diately
stop
thecar
and
turn
off
the
engine
.
Have
the
vehicle



A
towing
eye
is
provided
in
the
luggage
compartment
tool
kit
.
flat-bedded
or
towed
to
an
authorized
service
center
and
have



The
towing
eye
can
be
screwed
into
the
front
or
rear
bumper
.
the
engine
oil
pressure
checked
.



See
Fig
.
18
and
Fig
.
19
.

Low
Oil
Pressure

NOTE-

Detafed
information
on
checking
the
oil
pressure
is
covered
ín
119
Lubrication
System
.

Brake
Fluid
Leve¡

The
brake
fluid
leve¡
warning
light
may
bean
indicator
of
brake
fluid
loss
.
Problems
with
the
brakesystem
should
be
checked
and
repaired
immediately
.
See
340Brakes
for
more

information
.

Check
Engine
Warning
Light

Dim
Lights

FUNDAMENTALS
FOR
THE
DO-IT
YOURSELF
OWNER



010-13

If
the
"CHECK
ENGI
NE"
warning
light
comes
on
or
flashes,
it
indicates
that
an
emissions-related
fault
has
occurred
.
Faults
suchas
a
failed
oxygen
sensor
or
a
faultyfuelinjector
can
tum

the
light
on,
causing
the
exhaust
or
evaporative
emissions
to

exceed
a
specified
limit
.
The
engine
can
be
safely
driven
with

the
light
on,
although
the
emission
systems
should
be
checked

assoonas
possible
.
See
100
Engine-General
for
more
infor-

mation
on
the
Check
Engine
Light
and
the
On-board
diagnostic

system
.

Headlights
and
instrument
panel
illuminationthat
are
dim
or

gradually
getting
dimmer
generally
indicate
a
problem
with
the

battery
or
charging
system
.
The
battery
charge
indicator
light

may
come
on
as
the
lights
are
dimming
.
In
either
case,
theen-

gine
and
accessories
are
running
off
of
the
battery
alone,
and

will
soon
discharge
it
altogether
.

If
possible,
do
not
stop
the
engine
unless
you
have
the
capa-

bility
to
jump
start
¡t
.
There
may
not
be
enough
power
in
the

starting
system
torestart
the
engine
.
Instead,turn
off
as
many

electrical
consumers
as
possible
.
This
will
reduce
the
current

drain
and
will
allow
thecar
to
be
driven
farther
before
you
lose

all
battery
power
.

Fig
.
18
.
Pry
open
rear
tow
lúg
access
panel
.

When
towingthecar
from
the
front
with
the
rear
wheelson

the
ground,
a
maximum
distance
of
20
miles
is
acceptable
.
If

thecar
needs
to
be
towed
further,
have
the
rear
wheels
placed
on
dollies
.

CA
UTION-

"
Do
not
tow
with
sling-type
equipment
The
front
spoilers
andbumper
covers
may
sustain
dam-
age
.

"
Towínga
BMW
with
an
automatic
transmission
with
the
rear
wheelson
the
ground
can
resuft
in
transmission
damage
due
to
lackof
lubrication
and
should
be
avoided
.

0013128

EMERGENCIES

010-14



FUNDAMENTALS
FOR
THE
DO-ITYOURSELF
OWNER

Fig
.
19
.
Instaf
rear
tow
lug
into
threaded
hole
.

if
absolutely
necessary,
cars
with
automatic
transmissions
can
be
towed
with
the
rear
wheels
on
the
ground,
butthe
tow

should
not
exceed
25
miles
(40
km),at
speeds
at
or
below30
mph
(35
km/h)
.
Be
sure
the
transmission
fluid
hasbeen
topped

off
before
starting
the
tow
.
Always
tow
thecar
with
the
transmis-

sion
lever
in
"N"
(neutral)
.
If
the
tow
must
exceed25
miles
(40

km),
add
one
quart
of
ATF
to
the
transmission,
or
better
yet,
re-

move
the
driveshaft
.
Be
sure
to
drain
or
pump
outthe
added
flu-
id
once
the
tow
has
been
completed
.

NOTE-

"
ATF
draining
and
filling
is
covered
in
240
Automatic
Transmission
.

"
Driveshaft
removal
is
covered
in
260
Driveshaft
.

EMERGENCIES

úo1W¿b

Spare
Parts
Kit

Carrying
a
basic
set
of
spare
parts
can
prevent
a
minor

breakdown
from
turning
into
a
major
annoyance
.
Many
of
the

following
itemswon't
allow
you
todo
major
repair
workon
the

car,
but
they
will
help
in
the
event
of
the
failure
of
something
that

can
disable
thecar
or
compromise
its
safety
.

Spare
Parts
Kit
-
Basic
Contents

"
Drive
belt
(V-belt
or
poly-ribbed)

"
Engine
oil
(one
or
two
quarts)

"
Engine
coolant
(1
gallonof
premixed
50/50
anti-freeze

and
water)

"
Fuse
assortment
(7
.5A,
10A,
15A,
20A)

"
Radiator
hoses
(upper
and
lower)

Spare
Parts
Kit
-
Additional
Contents

"
Exterior
lighting
bulbs
(headlight,
brakelight,
turn
signal,

and
taillight)

"
Wiper
biades

"
Brake
fluid
(new
unopened
bottle,
DOT
4
specification)

"
Main
relay
for
DME
system

100-4
ENGINE-GENERAL

'



TEMP

PRECAT



POST
CAT



OXYGENSENSOR
HEATING

#
.
THROTTLE
POSITION



FUEL
INJECTOR
CONTROL
(SEQUENTIAL)

OPERATING
POWER



00

CAMSHAFT
POSITION
SENSOR

ECM



I
MAIN
GROUND

RELAY



J_



-



AC
COMPRESSOR
RELAY
CONTROL

TERMINAL
15

MEMORY
POWER
FUEL
PUMP
RELAY
CONTROL
AUX
GROUND
P

CRANKSHAFT
POSITION
dESENSOR

INTAKE
AIR

ENGINE
COOLANT
TEMP

FUEL
TANK
PRESSURE
SENSOR

S-EML
S-MSR

ASC
S-ASC

VEHICLE
SPEED

LOW
FUEL
LEVEL

A/C
SWITCH
ON
(AC)
E36
IHKA
COMPRESSOR"ON"

SIGNAL
(KO)

INDIVIDUAL
SERIAL
NUMBER

MS41
.1

SECONDARY
AIR
1NJECTION
AIR
PUMP®
RELAY
CONTROL

IDLE
CONTROL
VALVE



'M

FUEL
INJECTION
(TI)

ENGINE
SPEED
(TD)

Fig
.
5
.



Siemens
MS
41
.1
OBD
II
engine
management
systemusedon
1996
and
later
M52
engines
.

GENERAL

IGNITION
COILS
CONTROL

L
r"Q
if~
CIYVFIYC



CHE
AMP
CONTROL
ENGINE

THROTTLE
POSITION

6

ECM
RELAY
CONTROL

ASC

THROTTLE
..
:
.
.
..
-11



1Q\\\
POTENTIOMETER
POWER

CAN



TCM
II



SCAN
(DES
;
ER

DIAGNOSIS

OBD
II
I
II

GENERIC
SCANTOOL



0012596

100-6
ENGINE-GENERAL

Cylinder
compression,
checking

A
compression
tester
is
needed
to
make
a
compression
test
.

To
obtain
accurate
test
results,
the
battery
and
starter
must
be
capable
of
cranking
the
engine
at
250-300
rpm,
and
theen-

gine
should
be
at
normal
operating
temperature
.
Use
com-

pressed
air
to
clean
aroundthe
spark
plugs
before
removal
.

1
.
Disable
the
ignítion
system
by
removing
the
engine

management
system
main
relay
and
the
fuel
pump
re-
¡ay
.
See
Fig
.
6
.

WARNING
-

The
ignítion
system
produces
high
voltages
that
canbe
fatal
.
Avoid
contact
with
exposed
termínals
and

useextreme
caution
when
working
on
acar
wíth
the
ignítion
switched
on
or
the
engine
running
.

Fuel



DM
E
pump
main
re
ay



rel
ay
o
oa
ooa

.,
o00
oao

Fig
.
6
.



Engine
management
relays
in
power
distribution
box
inleft
rear
of
engine
compartment
.

CAUTION-

"
On
OBD
11
cars,
making
a
compression
test
may
causea
faultto
set
in
the
ECM
and
may
also
il-
luminate
the
Check
Engine
light
.
The
light
can
only
be
tumed
out
using
special
scan
tool
equip-
ment,using
eíther
the
BMW
specialservíce
tool
or
using
a
"generic"
OBD
11
scan
tool
.
Discon-
necting
the
battery
will
not
erase
the
fault
mem-
orynor
turn
outthe
light
.

0013034,

0012630

Fig
.
7
.



Remove
spark
plug
wires
from
spark
plugs
on
4-cylinder
en-
gine
using
special
tool
.
Tool
is
stored
under
cover
at
rear
of
cylinder
head
(arrow)
.

Fig
.
8
.



Remove
engine
cover
on
6-cylinder
engine
byprying
off
nut
covers
and
removing
nuts
(A)
.
Be
careful
not
to
let
rubber
in-
sulators
fall
off
as
cover
is
removed
(arrows)
.

4
.
On
6-cylinder
engines,
disconnect
the
harness
connec-
tors
from
the
ignítion
coils
by
lifting
the
retaining
clip
.

Remove
the
coil
mounting
nuts
andremove
the
six
coils
.
See
Fig
.
9
.
Remove
the
sparkplugs
.
"
Failure
to
remove
the
main
relay
or
attempting
to
disable
the
ignítion
system
by
other
methods
may
resultin
damage
to
the
engine
control
module
.



NOTE-

Used
sparkplugs
should
be
reinstalled
in
the
same
cyl-

2
.
On
4-cylinder
engine
:
Remove
plastic
engine
cover
from



inder
fromwhich
they
were
removed
.

top
of
cylinder
head
.
Disconnect
spark
plug
wires
and
re-
move
spark
plugs
.
See
Fig
.
7
.



5
.
Insta¡¡
the
compression
gauge
in
the
first
cylinder's

3
.
On
6-cylinder
engine
:
Remove
top
engine
coverby
pry-



spark
plug
hole,
tight
enough
to
form
a
good
seal
.

ing
off
nut
covers
and
removing
mounting
nuts
.
See
Fig
.
8
.

MECHANICAL
TROUBLESHOOTING

eiioo4

Fig
.
9
.



Remove
ignition
coils
on
6-cylinder
engine
by
disconnecting
harness
connector
and
removing
mounting
bolts
(arrows)
.

NOTE-

"
The
compression
gauge
reading
shoutd
increase
with
each
compression
stroke
and
reach
near
its
maxi-
mum
reading
in
about
4-6
strokes
.

"All
cylinders
shoutdreach
maximum
compression
in
the
same
number
of
strokes
.
If
a
cylinder
needs
sig-
nificantly
more
strokes
to
reach
maximum
compres-

sion,
there
is
a
problem
.

7
.
Release
the
pressure
at
the
compression
gauge
valve,

then
remove
the
gauge
from
the
spark
plughole
.
Re-

peat
the
test
for
each
of
the
other
cylinders
and
com-

pare
the
results
with
the
values
given
below
.

ENGINE-GENERAL
1
:00-
7

Compression
Pressure

"
Minimum
..........
.
.
..
..
10-11
bar
(142-156
psi)

"
Maximum
difference
between
cylinders
..
.....
.........
0
.5
bar
(7
psi)

Reinstall
the
spark
plugs
and
spark
plug
wires
or
ignition

cofs
.
The
remainder
of
installation
is
the
reverse
of
removal
.
Be
sure
to
reihstall
al¡
wires
disconnected
during
the
test,
especial-

¡y
ground
wires
at
the
coils
and
cylinder
head
cover
(where
ap-
plicable)
.

Tightening
Torque

"
Spark
plug
to
cylinder
head
.......
25
Nm
(18
ft-Ib)

Low
compression
indicates
a
poorly
sealed
combustion

6
.
With
the
parking
brake
set,
the
transmission
in
Park
or



chamber
.
Relatively
even
pressures
that
are
below
specification

Neutral,
and
the
accelerator
pedal
pressed
to
the
floor,



normally
indicate
worn
piston
rings
and/or
cylinder
walls
.
Erratic

crank
the
engine
with
the
starter
.
Record
the
highest



values
tend
to
indicate
valve
leakage
.
Dramatic
differences
be

value
indicated
by
the
gauge
.



tween
cylinders
are
often
the
sign
of
a
failed
head
gasket,

bumed
valve,
or
broken
piston
ring
.

Engine
Mechanical
Troubleshooting
Table

Table
c
lists
the
symptoms
of
common
engine
mechanical

problems,
their
probable
causes
and
the
suggested
corrective

actions
.
The
bold
type
indicates
the
repair
groups
where
appli-

cable
test
and
repair
procedures
can
befound
.

MECHANICAL
TROUBLESHOOTING