1993 BMW M3 throttle

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

113-2



CYLINDER
HEAD
REMOVAL
AND
INSTALLATION

0011s6i



-

0Fig
.
1
.



Front
exhaust
pipe
to
exhaust
manifold
mountíng
nuts
(arrows)
.
-1



~~
0013023

4
.
Remove
air
filter
housing
complete
with
mass
air
flow



Fig
.
3
.



Coolant
hose
connection
beneath
intake
manifold
on
M42

sensor
and
attached
hoses
and
ducting
.
See
Fig
.
2
.



engine
(arrow)
.

0011969

Fig
.
2
.



Air
filter
housing/air
intake
connections
on
M44
engine
with
traction
control
.
Clamp
atthrottle
housing
(A)
;
mass
air
flow
sensor
connector
(B)
;
and
clips
at
upper
air
filter
housing
(C)
.

Coolingsystem,
draining

5
.
Draincoolant
from
engine
block
and
radiator
.
See
170

Radiator
and
Cooling
System
.

NOTE-

"
The
block
drain
is
on
the
exhaust
sideof
the
engine,
near
cylinder
no
.
4
.

6
.
Disconnect
hoses
from
coolant
flange/thermostat
hous-
ing
on
frontof
cylinder
head
.
Unbolt
thermostat
housing
from
cylinder
head
.

CYLINDER
HEAD,
4-CYLINDER

7
.
On
M42
engines,
disconnect
hose
from
coolant
pipe
on

left
side
of
engine
.
See
Fig
.
3
.

8
.
Disconnect
heater
hoses
from
coolant
flange
on
rear
of
cylinder
head
.

Cylinder
head
cover,
removing

9
.
Remove
ignition
coil
pack
from
rightstrut
tower
.
See

Fig
.
4
.

0011995
"
The
radiator
drain
plug
is
on
the
bottomof
the
radiator



Fig
.
4
.



Cylinder
head
cover
showing
location
of
engine
breather
hose
on
the
driver's
side
.
Remove
small
plastic
lock
clipto



(A),
wiring
harness
duct
(B),
and
ignition
coil
pack
(C)
.
M44
pull
radiator
drain
plug
out
completely
.



engine
shown
.
Cover
on
M42
engine
is
similar
.

10
.
Disconnect
engine
breather
hose
from
cylinder
head
cover
.

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

113-10



CYLINDER
HEAD
REMOVAL
AND
INSTALLATION

Tightening
Torques

"
Coolant
drain
plug
to
cylinder
block
.
.
25
Nm
(18
ft-1b)

"
Intake
manifold
support
to
manifold
.
.
15
Nm
(11
ft-Ib)

"
Lower
intake
manifold

to
cylinder
head
.
..........
.
..
...



15
Nm
(11
ft-Ib)

"
Lower
intake
manifold

to
upper
manifold
..........
.
..
...
15
Nm
(11
ft-Ib)

"
Radiator
cooling
fan
to
coolant
pump
.
40
Nm
(30
ft-Ib)

"
Radiator
drain
screw
to
radiator
...
.
2
.5
Nm
(22
in-lb)

CYLINDER
HEAD,
6-CYLINDER

For
ease
of
use
this
procedure
is
broken
into
subsections,

as
follows
:

General
Coolingsystem,
draining
Cyiinder
head
cover,
removing

Intake
manifold,
removing

Timing
chains,
uncoupling

Cylinder
head
assembly,
removing

WARNING
-

Allow
the
engine
to
cool
before
beginning
this
pro-
cedure
.

General

1
.
Working
inside
luggage
compartment,
disconnect
neg-
ative
(-)
battery
cable
.

CAUTION-

"
Prior
to
disconnectiog
the
battery,
read
the
bat-
tery
disconnection
cautions
given
at
the
front
of
this
manual
on
page
vi¡¡
.

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

2
.
Remove
front
exhaust
pipes
from
manifolds
.
Discard
nuts
.

3
.
Remove
air
filter
housing
complete
with
mass
air
flow
sensor
and
intake
air
ducting
.
Disconnect
vacuum
hos-
es
from
throttle
housing
.

4
.
On
M52
and
S52US
engines
:
Remove
secondary
air
injection
check-valve
from
front
of
engine
and
set
aside
.

CYLINDER
HEAD,
6-CYLINDER

Coolingsystem,
draining

5
.
Drain
engine
coolant
and
Rmove
coolant
hoses
from

thermostat
housing
.
Drain
engine
block
by
removing

block
drain
.
See
170
Radiator
and
Cooling
System
.

NOTE-

The
block
drain
is
on
the
exhaust
side
of
the
engine,
near
cylinder
no
.
5
.

6
.
Remove
radiator
cooling
fan
and
fan
shroud
.
See
170

Radiator
and
Cooling
System
.

NOTE-

The
radiator
cooling
fannut(32
mm
wrench)
has
left-
hand
threads
.

Cylinder
head,
removing

(6-cylinder
engine)



7
.
Disconnect
heater
hoses
at
rear
of
cylinder
head
.
See

Fig
.
26
.

'i

8
.
Remove
alternator
cooling
duct
.

Cylinder
head
cover,
removing

0012687

Fig
.
26
.
Disconnect
heater
hoses
at
heater
valve
(A)
and
heater
core
(B)
.

9
.
Remove
air
plenum
from
rear
of
engine
compartment
.

See640
Heating
and
Air
Conditioning
.

10
.
Remove
plastic
cylinder
head
covers
from
above
fuel
injectors
and
ignition
coils
.
Pull
larger
cover
forward

when
removing
.
See
Fig
.
27
.

11
.
Disconnect
crankcase
ventílation
hose
fitting
from
cyl-
inder
head
cover
.

12
.
Disconnect
ignition
coil
harness
connectors
from
coiis
.

Remove
ignition
coiis
and
spark
plugs
.
See
120
Igni-
tion
System
.

Fig
.
27
.
Remove
top
enginecovers
by
prying
out
plugs
and
removing

nuts
(A)
.
Make
sure
rubber
insulators
on
either
side
of
large

cover
do
not
fall
off
during
cover
removal
(B)
.

Fig
.
28
.
Fuel
injection
harness
beíng
lifted
off
engine
to
be
placed
at

base
of
windshield
(A)
.
Ignitioncoils
are
also
visible
(B)
.
M50

engine
shown,
other
6-cylinder
engines
are
similar
.

14
.
Remove
cylinder
head
cover
mounting
bolts
and
re-

move
cylinder
head
cover
.

CYLINDER
HEAD
REMOVAL
AND
INSTALLATION



113-
11

15
.
Remove
oil
baffle
cover
from
above
intake
camshaft
.

See
Fig
.
29
.

Fig
.
29
.
Camshaft
oil
baffle
coverbeing
removed
.

NOTE-

The
cylinder
head
cover
mounting
bolt
insulators
and

13
.
Remove
hold
down
nuts/bolts
from
fuel
injection
har-



gaskets
should
be
reinstalled
in
the
same
order
.
Make

ness
.
Pry
back
injector
connector
retaining
clips
and
lift



note
of
their
arrangement
during
removal
.

entire
harness
off
engine
.
See
Fig
.
28
.

Intake
manifold,
removing

811119

16
.
Disconnect
vacuum
hose
from
brake
system
vacuum

booster
.
Plug
opening
in
booster
.

17
.
Remove
throttle
housing
mounting
bolts
and
remove

throttle
housing
.
Set
throttle
housing
aside
without
dis-

connecting
cablesor
coolant
hoses
.
See
Fig
.
30
.

Fig
.
30
.
Remove
4
comer
bolts
(arrows)
from
throttle
housing
and

unbolt
complete
assembly
from
intake
manifold
.
Remove

complete
throttle
assembly
without
disconnecting
connec-

tors,
hoses
or
cables
.
(M50
engine
shown
.)

CYLINDER
HEAD,
6-CYLINDER

GENERAL
.
.
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.
.........
130-2



Intake
air
temperature
(IAT)
sensor,

Principles
of
Operatinn
.
.
.
.
.
.
.
.
.
.........
130-2



testing
and
replacing
...
.
...
.
.
.
.......
.
130-19

Basic
Engine
Settings
.
.
.
.
.
.
.
.
.
.
.
.
.
.
...
:
.
130-3



Throttle
position
sensor
(TPS),

DISA
(Dual
Resonance
Intake
System)
.
.
.
.
.
130-3



testing
and
replacing
...
.
...
.
.
.
.
.
...
.
.
.130-19

On-Board
Diagnostics
(OBD)



Idle
speed
control
valve,
testing
.
.
.
.
.
.
.
.
.
.
130-20

and
Fault
Diagnosis
.
.
....
.
......
.
.
.
...
130-4



Idle
speed
control
valve,
replacing
.
.
.
.
.
.
..
130-21

SecondaryAir
Injection
.
.
.....
.
.........
.
130-5



BOSCH
DME
M5
.2
COMPONENT
Warnings
and
Cautions
.
.
...
.
.
.
.........
.
130-6



REPLACEMENT
.....
.
......
.
....
.
.
.
..
130-21

ELECTRICAL
CHECKSAND



Mass
air
flow
sensor,
replacing
.
.
....
.
....
130-22

COMPONENT
TESTING
.
.
.
.
.
.
.
.
...
.
.
.
.
.
130-7



Engine
coolant
temperature
(ECT)

Main



sensor,
replacing
..
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
130-22
rela
y
testing



130
-7
,...
.
.
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.



Intake
air
temperature
(IAT)
sensor,
Fuel
pump
relay,
testing
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.
130-7



rep
lacin
.
.
.
.
.
.
.
.
.
.
.g



.
.
.
.
.
.
.
...
.
.
.
..
.130-22
Oxygen
sensor,
testing
(Boschsystems
only)
130-8



Throttle
poson
sensor
(TPS)
replacing



13022
,



..
.-

FUEL
DELIVERY
TESTS
...
.
....
.
.
.
...
.
130-9



Idle
speed
control
valve,
replacing
...
.
....
.130-23

Operating
fuel
pump
for
tests
.
.
.......
.
...
130-9



SIEMENS
MS
41
.1
COMPONENT
Relieving
fuel
pressure
and



REPLACEMENT
.
...
.
.
.
.
.
.......
.
....
.130-23
connecting
fuel
pressure
gauge
......
.
..
130-10

Residual
fuel
pressure,
testing
.
.....
.
.
.
.
.
130-10



Mass
air
flow
sensor,
replacing
.
.......
.
.
.130-25

Fuel
pressure
regulator
response



Engine
coolant
temperature
(ECT)

to
engine
load,
testing
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
130-11



sensor,
replacing
.....
.
.
.
.
.
.........
.130-25

Fuel
rail
and
injectors,
checking
...
.
.
.
.
.
.
.
130-11



Intake
air
temperature
(IAT)
sensor,
replacing
.
.
.
.
.
.....
.
.
.
.
.
.
.
.......
.
.
.130-25
Fuel
rail
and
injectors,
replacing



..
.
.
.
.
.
.
.
130-12



Throttleposition
sensor
(TPS),
replacing
.
.
.
130-26
Fuel
PressureRegulator
.........
.
.
.
.
.
.
.
130-13



Idle
s
eed
control
valve,
re
lacin



130-26
Fuel
pressure
regulatorreplacing



p



p



g
.'''...
.
'
,

(fuel
rail
mount)
...
.
.
.
.
.
.............
130-13



ECM
PIN
ASSIGNMENTS
.............
.
.
130-26
Fuel
pressure
regulator,
replacing



Engine
control
module
(ECM),
accessing
...
130-26
(undercar
mount)
.
.
.
.
.
.
.
.
.........
.
.
130-14

BOSCH
DME
M1
.7
COMPONENT

TESTS
AND
REPAIRS
.
.
.
.
.
...
.
.
.
.
.
.
.
.
130-14

Air
flow
sensor,
testing
and
replacing
.
.
.
.
.
.
130-14

Engine
coolant
temperature
(ECT)

sensor,
testing
and
replacing
...
.
.
.
.
.
.
.
.
130-15

Throttle
position
sensor
(TPS),

testing
and
replacing
.
..........
.
.....
130-16

Idle
speed
control
valve,
testing
and
replacing
.
.
.
.
.
............
130-16

BOSCH
DME
M3
.1
AND
M33
.1

COMPONENT
TESTS
AND
REPAIRS
.
.
.
130-17

Mass
Air
Flow
Sensor
.
.
.
.
.
.
.
.
.....
.
.
.
.
.130-17

Mass
air
flow
sensor
(hotwire),testing
and
replacing
.
.
.
.
.
.....
.
.
.
.
.
.
.
130-17

Mass
air
flow
sensor
(hot
film),

testíng
and
replacing
.
.
.
.....
.
.
.
.
.
.
.
.
.
130-18
Engine
coolant
temperature
(ECT)

sensor,
testing
and
replacing
..
.
.
.
.
.
...
.
130-18

130
Fuel
i
n
jection

FUEL
INJECTION



130-1

TABLES
a
.
Engine
Management
System
Variants
.........
.130-2
b
.
Mass
Air
Flow
Sensor
Variants
..
.
..
..........
.130-2
c
.
Fuel
Pressure
Specifications
..
.
.
...
..........
130-11
d
.
Engine
Coolant
Temperature
Sensor
or
Intake
Air
Temperature
Sensor
Test
Values
(DME
1
.7)
...
.
130-15
e
.
ThrottlePosition
Sensor
Tests
(DME
1
.7)
......
.130-16
f
.



Engine
Coolant
Temperature
Sensor
or
Intake
Air

Temperature
Sensor
Test
Values
(DME
3
.1/3
.3
.1)130-19
g
.
Throttle
Position
Sensor
Tests
(DME
3
.1/3.3
.1)
.
.130-20
h
.
ECM
Pin
Assignment-Bosch
DME
M1
.7
....
.
..
.130-28
i.



ECM
Pin
Assignment-Bosch
DME
M3
.1
.......
.130-30
j
.



ECM
Pin
Assignment-Bosch
DME
M3
.3
.1
.....
.130-32
k
.
ECM
Pin
Assignment-Bosch
DME
M5
.2
.......
.
130-34
I.



ECM
Pin
Assignment-Siemens
DME
MS
41
.1
..
.
130-36

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
.

FUEL
INJECTION



130-
3

Fuel
metering
.
The
ECM
meters
fuel
bychanging
the



The
engine
management
system
compensates
automatical-
opening
time
(pulsewidth)
of
the
fuel
injectors
.
To
ensure
that



ly
for
changes
in
the
engine
due
to
age,
minor
wear
or
small
injector
pulsewídth
is
the
only
factor
that
determines
fuel
me-



problems,
such
as
a
disconnected
vacuum
hose
.
Asa
result,
tering,fuel
pressure
is
maintained
bya
fuel
pressure
regula-



idle
speed
and
mixture
do
not
need
lo
be
adjustedas
partof
tor
.
The
injectors
are
mounted
lo
a
common
fuel
supply
called



routine
maintenance
.
the
fuel
rail
.

The
ECM
monitors
engine
speed
to
determine
the
duration



NOTE-

ofinjector
openings
.
Other
signals
to
the
ECM
help
determine



Poordriveabilitymaybe
encountered
when
the
batteryis

injector
pulse
time
for
different
operating
conditions
.
A
tem-



disconnected
and
reconnected
.
when
the
battery
is
dis-
connected,
the
adaptive
memory
is
lost
The
system
will
perature
sensor
signals
engine
temperature
for
mixture
adap-



readaptafterabout
ten
minutes
of
drfving
.
tion
.
A
throttle
position
sensor
signals
throttle
position
.
The
exhaust
oxygen
sensor(s)
signal
information
about
combus-
tion
efficiency
for
control
of
the
air-fuel
mixture
.
1992
to
1995



DISA
(Dual
Resonance
Intake
System)
engines
are
equipped
with
a
single
sensor
.
1996
and
later
(OBD
II)
engines
are
equipped
with
an
oxygen
sensor
before



TheE36
4-cylinder
engine
is
equipped
with
a
dual
intake
andone
after
each
catalytic
converter
.
Forexample,the
M52



runner
system,
termed
DISA
.
DISA
offers
the
advantages
of
engine
is
equipped
withfour
oxygen
sensors
.



both
short
and
long
intake
pipes
.
Long
intake
runners
are
most
useful
at
low
to
medium
engine
rpm
for
producing
good
Idle
speed
control
.
ldle
speed
is
electronically
controlled



torque
characteristics
.
Short
intake
runners
produce
hígherviathe
idle
speed
control
valve,
which
maintains
idle
speed
by



horsepower
at
hígher
engine
speeds
.
bypassing
varying
amounts
of
air
around
theclosed
throttle
valve
.
Idle
speed
is
not
adjustable
.



NOTE-

Knock
(detonation)
control
.
Knock
sensors
monitor
and



The
term
DISA
comes
from
the
German
words
Differen-

control
ignition
knock
through
the
ECM
.
The
knock
sensors



zierte
Sauganlage,
and
can
roughlybe
translated
as
"dif-
fering
intake
manifold
configuration
."
See
100
Engine-
function
like
microphones
and
are
able
to
convert
mechanical



General
foradditional
information
on
DISA
operation
.
vibration
(knock)
into
electrical
signals
.
The
ECM
is
pro-

grammed
to
react
to
frequencies
that
are
characteristic
of
en-



Manifold
construction
:
The
intake
manifold
is
a
two-piece
gine
knock
and
adapt
the
ignition
timing
point
accordingly
.



metal
construction,
with
a
pair
of
runners
in
thetop
section
See120
Ignition
System
for
further
details
.



and
four
runners
in
the
lower
section
.
A
butterfly
valve
is
in-
stalled
in
the
lower
section,
enabling
the
DISA
solenoid
toiso-

NOTE-



late
one
pair
of
runners
from
the
other
pair
.
See
Fig
.
2
.

The
1992
M50
engine
is
not
equipped
with
knock
sen-



Operation
.
With
the
DISA
butterfly
valve
closed,
the
pipes
sors
.
All
other
engines
are
equipped
with
two
knock



in
thetop
half
of
the
manifold
act
together
with
the
ram
air
sensors
.



pipes
in
the
lower
halfto
producea
single,
long
air
intake
pipe
for
each
cylinder
.
See
Fig
.
3
.
The
column
of
aír
oscíllating
in

Basic
Engine
Settings



this
combined
pipe
significantly
increases
engine
torque
in
the

medium
rpm
range
.

Idle
speed,
idle
mixture
(%CO),
and
ignition
timing
arenot

adjustable
.
The
adaptive
engine
management
system
is
de-

signed
to
automatically
compensate
for
changes
in
engine
op-

eratingconditions,
although
the
adaptive
range
is
limited
.
Once

these
limits
are
exceeded,
driveability
problems
usually
be-

come
noticeable
.

Above
approximately
4,800
rpm,
the
butterfly
valve
between
the
intake
air
pipes
for
the
two
cylinder
groups
is
opened
.
The
shorter
pipes
in
the
lower
manifold
section
now
become
the

main
suppliers
of
ram
air
to
the
cylinders,yielding
greater
pow-

er
at
the
upper
end
of
the
engine
rpm
range
.
See
Fig
.
4
.

Control
components
.
The
DISA
butterfly
valve
is
actuated

NOTE-



electro-pneumatically
via
the
engine
control
module
(ECM)
.

lf
the
system
adaptive
limits
are
exceeded,
the
Check



The
valve
begins
to
open
as
engine
speed
rises
aboye
4,840

Engine
light
will
most
likely
come
on,
indicating
an



rpmand
closes
below
4,760
rpm
.
The
action
of
the
valve
is
de-
emissions-
related
fault
For
Check
Engine
light
diag-



liberately
delayed
to
prevent
it
from
opening
and
closing
repeat-
nostics,
see100
Engine-General
.



edly
within
a
short
time
.

GENERAL