Maf BMW 325i 1994 E36 Workshop Manual

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
.

AUTOMATIC
TRANSMISSION



240-1

240
Automatic
Transmission

GENERAL
.....
.
.
.
.
.
.
.
.
.
.
.
.
.
.........
.
240-1



TRANSMISSION
REMOVAL
AND

INSTALLATION
..................
.
.
.
.
.240-4
TRANSMISSION
SERVICE
.
.
.
.
.
.......
.
240-1



Transmission,
removing
and
installing
....
.
.
.240-4

ATF
leve¡,
checking
..
.
.
.
.
.
.
.
.
.
..........
240-1

ATF,
draining
and
filling
.
.
.
.
.
.
.
..........
240-2



TABLE

a
.
Automatic
Transmission
Gear
Ratios
.......
..
.
.
240-1

GENERAL



TRANSMISSION
SERVICE



lo

Automatic
transmissions
are
identified
by
code
letters



ATF
leve¡,
checking

foundon
a
data
plate
located
on
the
sideof
thetransmission

case,
behind
the
manual
valve
lever
.
See
200Transmis-



The
automatic
transmissions
installed
in
the
E36
models
sion-General
for
application
information
.
Forgear
ratio
spec-



are
normally
filled
with
Dexron
III
automatic
transmission
fluid

ifications,
see
Table
a
.



(ATF),
although
alternative
fluids
have
been
installed
from
the

factory,
depending
on
transmission
type
and
model
year
.

CAUTION-



Some
transmíssions
are
filled
with
a
special
BMW
"lifetime"

ATF
does
not
circulate
unless
the
engine
is
run-



automatic
transmission
fluid,
which
does
not
require
periodic

ning
.
When
towing
an
automafic
transmission
ve-



fluid
changes
.

hicle,
usea
flat-bed
truck
or
ralse
the
rear
wheels
off
the
ground
.



CAUTION-

Mixing
different
types
of
transmission
fluids
will

The
electronic
transmission
control
module
(TCM)
monitors



lead
to
transmission
failure
.

transmissionoperation
for
faults
and
alerts
the
driver
by
illumi-

nating
the
transmission
fault
indicator
on
the
instrument
pan-

el
.
On-board
diagnostic
codes
stored
in
the
TCM
mustbe



NOTE-

downloaded
and
interpreted
by
trained
technicians
using
spe-



The
transmission
lubricant
instafed
can
be
foundona

cial
BMW
diagnostic
equipment
.



type
plate
on
the
side
of
the
transmission
.
In
addition,
a
sticker
may
be
located
on
the
fluid
sump
indicatingthe
typeof
transmission
lubricant
used
.
Ifin
doubt,
con

NOTE-



sult
an
authorized
BMW
dealer
for
altemate
fluid
use

Internal
repairs
to
the
automatic
transmission
require



and
current
information
regardingtransmission
operat-
special
service
equipment
and
knowledge
.
If
it
is
deter-



ing
fluids
.

mined
thatinterna¡
service
is
required,
consult
en
au-

thorízedBMWdealerabouta
factoryreconditioned
unit



The
transmission
is
not
equipped
with
a
dipstick
.
Checking
or
a
transmission
rebuild
.



the
ATF
leve¡
requires
measuring
and
maintaining
a
specified

ATF
temperature
during
the
checking
procedure
.
The
check-

ing
temperature
is
not
fully
warm
orcold
(the
ATF
sump

should
be
approximately
warm
to
the
touch)
.

Table
a
.
Automatic
Transmission
Gear
Ratios

Transmission



MS
310R
(THM-R1)



MS
310R
(THM-Rl)



MS
310Z(5HP
18)



I



MS
270R
(THM-R1)
(1992-1993)(1993-on)

Gear
ratios
:
1st



2
.40



2
.86



3
.67



2
.86

2nd



1
.47



1
.62



2
.00



1
.62
3rd



1
.00



1
.00



1.41



1
.00
4th



0
.72



0
.72



1
.00



0
.72
5th



-



-



0
.74



-
Reverse



2
.00



2
.00



4
.10



2
.00

TRANSMISSIONSERVICE