1998 BMW 540i fuel type

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.
General
WARNING-
Never run the engine in tile work area unless it is well-ven-
tilated. The exhaust should be vented to the outside. Car-
bon monoxide (CO) in exhaust kills.
Remove all neckties,
scarfs, loose clothing, or jewelry
when working near a running engine or power tools.
Tuck in shirts. Tie long hair and secure it under a cap.
Severe injury can result from these things being
caugiit
in rotating parts.
Remove rings, watches, and bracelets. Aside from the
dangers of moving parts, metallic jewelry conducts
electricity and may cause shorts, sparks, burns, or
damage to the electricalsystem when accidentally con-
tacting the battery or other electrical terminals.
Disconnect the battery negative
(-) cable whenever
working on or near the fuel system or anything that is
electrically powered. Accidental electrical contact may
damage the electrical system or cause a fire.
Fuelis highly flammable. When working around fuel, do
not
smoke or work near heaters or other fire hazards.
Keep an approved fire extinguisher handy.
The fuel system is designed to retain pressure even
when the ignition is off When worlcing with the
fuelsys-
tem, loosen the fuel lines slowly to allow the residual
pressure to dissipate gradually. Take precautions to
avoid spraying fuel.
. Illuminate the worlc area adequately and safely Use a
portable safety light for worlcing inside or under the car.
A fluorescent type
light is best because it gives off less
heat. If using a light with a normal incandescent bulb,
use rough service bulbs to avoid
breakage. The hot fil-
ament of an accidentally broken bulb can ignite spilled
fuel or oil.
Keep sparks, lighted matches, and any open flame
away from the top of the battery. Hydrogen gas
emitted
by the battery is highly flammable. Any nearby source
of ignition may cause the battery to explode.
Never lay
tools or parts in the engine compartment or
on top of the battery. They may
fallinto confinedspaces
and be difficult to retrieve, become caught in belts or
other rotating parts when the engine is started, or
cause electrical shorts and damage to the electrical
system.

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01 0-1 4
General
Specialty tool suppliers
Peake Research, Automotive Products Division
P.O. Box 28776
San Jose, CA 95159
408-369-0406
[email protected]
http://www.peakeresearch.com
Basic tool requirements
The basic hand tools described below can be used to accom-
plish most of the simple maintenance and repair tasks.
Screwdrivers
4 The common flat-blade type, Phillips type, and TorxO type
screwdrivers will handle almost all screws used on
BMWs.
Two or three different sizes of each type will be required,
since a screwdriver of the wrong size will damage the screw
head.
Wrenches
4 Wrenches come in different styles, including open-end. 12
point box-end,
6 point box-end and flare nut. The basic open-
end wrench is the most widely used, but grips on only two
sides. The box-end wrench has better grip on all six sides of
a nut or bolt.
A 12 point box-end can loosen a nut or bolt where there is less
room for movement, while
a 6 point box-end provides better
grip. For hex fasteners on fluid lines, like brake lines and fuel
lines, a flare-nut wrench offers the advantages of a box-end
wrench with a slot that allows it to fit over the line.
The combination wrench is the most universal. It has one
open-end and one box-end. 10 mm and 13 mm wrenches are
the most common sizes needed.
A more complete set of
wrenches would include
6 mm through 19 mm sizes.

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General
Torque wrench
A torque wrench is used to precisely tighten threaded fasten-
ers to a predetermined value. Many of the repair procedures
in this manual include BMW-specified torque values
in New-
ton-meters (Nm) and the equivalent values in foot-pounds
(ft-
Ib).
4 Several types of torque wrenches are available. An inexpen-
sive beam-type (top) is adequate but must be read visually. A
ratchet-type (bottom) can be preset to indicate (click) when
the torque value has been reached. They all do the same job,
but offer different convenience features at different prices.
The most convenient ones have a built-in ratchet, and can be
preset to indicate when a specific torque value has been
reached. Follow the wrench manufacturer's directions
for use
to achieve the greatest accuracy.
A torque wrench with a range up to about 150 Nm (1 10 ft-lb) BOIBFNG has adequate capacity for most of the repairs covered in this
manual. For recommended torque values of
10 Nm orbelow,
the English system equivalent is given in inch-pounds (in-lb).
These small values may be most easily reached using a
torque wrench calibrated in inch-pounds. To convert
inch-
pounds to foot-pounds, divide by 12.
Digital multimeter
4 Many of the electrical tests in this manual call for the mea-
surement of resistance (ohms) or voltage values. For safe
and accurate tests of sensitive electronic component and
systems, a multimeter or digital
volt/ohm meter (DVOM) with
high input impedance (at least
10,000Sr) should be used.
Some meters have automotive functions such as dwell and
pulse width that are useful for troubleshooting ignition and
fuel injection problems.
CAUTIOI\C
Vehicle electronic systems may be damaged by the high cur-
rent draw of a test light with a normal incandescent bulb. As
a general rule, use a high impedance digital multimeter or an
LED test light for all electrical testing.

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Maintenance
Suspension, front, inspecting
Inspection of the front suspension and steering includes a
check of all moving parts
forwear and excessive play. Inspect
ball joint and tie-rod rubber seals and boots for cracks
ortears
that could allow the entry of dirt, water, and other
contaminants. See
310 Front Suspension.
Suspension, rear, inspecting
Differential and rear drive axle service consists of checking
and changing the gear oil, inspecting for leaks, and checking
the drive axle
CV joint boots for damage.
The areas where
lealts are most likely to occurare around the
drive shaft and drive axle mounting flanges. For more infor-
mation on identifying oil leaks and theircauses, see
330 Rear
Suspension and
331 Final Drive.
Tires, checking inflation pressure
Correct tire pressures are important to handling and stability,
fuel economy, and tire wear. Tire pressures change with tem-
perature. Pressures should be
checked oRen during season-
al temperature changes. Correct inflation pressures can be
found on the driver's door pillar and in the owner's manual.
Note that tire pressures should be higher when the car is
more heavily loaded.
WARNING-
Do not inflate any tire to a pressure higher than the tire's max-
imum inflation pressure listedon the sidewall. Use care when
adding air to warm tires. Warm tire pressures can increase as
much as
4 psi (0.3 bar) over their coldpressures.
Tires, rotating
BMW does not recommend tire rotation. Due to the car's sus-
pension design, the front tires begin to wear first at the outer
shoulder and the reartires begin to wearfirst at the middle of
the tread or inner shoulder. Rotating the tires may adversely
affect road handling and tire grip.
Transmission service, automatic
The automatic transmissions installed in E39 models are
filled with special automatic transmission fluid. The transmis-
sion lubricant type can be found on the "type-plate" on the
side of the transmission. The recommended lubricants are
listed earlier in this repair group. See Fluids and lubricants.
If in doubt, consult an authorized BMW dealer for alternate

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120-3
Ignition System
Warnings and cautions
The ignition system produces dangerous high voltage. In ad-
dition the sensitive electronic components can be damaged
if
proper precautions are not adhered to.
WARNING-
* Do not touch or disconnect any cables from the coils while
the engine is running or being
cranked by the starter.
The ignition system produces high voltages that can be
fatal. Avoid contact with exposed terminals. Use ex-
treme caution when working on a car with the ignition
switched on or the engine running.
- Connect and disconnect tlie DME system wiring and
test equipment leads only when the ignition is
OFF:
Before operating the starter without starting the engine
(for example when
making a compression test) always
disable the ignition.
CA
U TIOW-
Do not attempt to disable the ignition by removing the coils
from the spark plugs.
Connect or disconnect ignition system wires, multiple
wire connectors, and ignition test equipment leads only
while the ignition is
off Switch multimeter functions or
measurement ranges only with the test probes discon-
nected.
* Do not disconnect the battery while the engine is run-
ning.
A high impedance digital multimeter should be used for
all voltage and resistance tests. An LED test light
should be used in place of an incandescent-type test
lamp.
In general, make test connections only as specified by
BMW as described in this manual, or as described by
the instrument manufacturer.
Engine management
BMW €39 engines use an advanced engine management
system known as Digital Motor Electronics (DME). DME in-
corporates on-board diagnostics, fuel injection, ignition and
other engine control functions. DME variants are listed in
Table a. Engine management systems.
Second generation On-Board Diagnostics
(OED II) is incor-
porated into the engine management systems used on the
cars covered by this manual. Use a BMW-specific electronic
scan tool, or a "Generic"
OED II scan tool to access Diagnos-
tic Trouble Codes (DTCs). DTCs can help pinpoint ignition
ine management problems.

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130-1 0
Fuel Injection
Remove MAF sensor:
Release clips from air filter housing
(A).
Disconnect harness connector (B).
Loosen intake boot clamp (C) and remove MAF sensor.
Note large sealing O-rings.
Installation is reverse of removal.
No adjustment to MAF sensor is possible.
Check intake hoses for cracks and vacuum leaks.
Engine coolant temperature (ECT) sensor,
testing and replacing
R
1 -4 The ECT sensor is located below cylinder 1 intake port
The ECT sensor is a dual temperature sensor. One circuit
provides coolant temperature information to the ECM while
the other circuit provides coolant temperature information to
the instrument cluster.
The ECM determines the correct ignition timing and
airlfuel
mixture required for the engine by monitoring an applied volt-
age
(5 vdc) to the sensor. The voltage drop across the sensor
varies as the coolant temperature (sensor resistance) chang-
es.
NOTE-
The ECT sensor is an NTC (negative temperature coeffi-
cient) type sensor. in other words, as the temperature rises,
resistance through the sensor decreases.
If the ETC sensor input is faulty or non-plausible, the MIL is il-
luminated when
OED II fault criteria are exceeded. The ECM
assumes asubstitute value
(80°C1 176°F) to maintainengine
operation. The ignition timing is set to a
conse~ativelsafe ba-
sic setting.
- Check ECT sensor resistance using a multimeter at sensor
terminals.
-
WARNING -
Due to risk of personal injury, be sure the engine is cold be-
fore disconnecting or reconnecting ECT sensor.
ECT sensor resistance @ 20" C (68°F) 2.2 - 2.7
Temperature gauge sensor resistance @ 20°C (~B"F)( 6.7 k

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Fuel Injection
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME system components.
Remove engine coolant temperature sensor:
Unclip crankcase vent hose
(C) from cylinder head cover.
Remove plastic cover
(6) from atop intake manifold run-
ners.
Working under front of intake manifold, disconnect ECT
harness.
Unscrew ECT sensor
(C) from cylinder head.
Installation is reverse of removal:
Use new copper sealing washers when installing sensor.
Replace any engine coolant lost.
Tightening torque
Temperature sensor to cylinder head
13 Nm (10 it-lb)
Intake air temperature ([AT) sensor,
testing and replacing
4 The intake air temperature (IAT) sensor (arrow) signal is
used by the ECM to monitor intake air temperature for fuel
and
igntion adaptation. The sensor is .ocared in rne 'ntane
man:lold behind the throttle housng.
The ECM monitors an applied voltage (5 vdc) to the sensor
The voltage drop across the sensor varies as the intake air
temperature (sensor resistance) changes.
NOJE-
The IATsensor is an NTC (negative temperature coefficient)
type sensor. In other words, as the temperature rises, resis-
tance through the sensor decreases.
If the IAT sensor input is implausible, a
fault code is set.The
MIL is illuminated when OED II fault criteria are exceeded.
The ECM then operates the engine using only the engine
coolant temperature (ECT) sensor input.
The intake air temperature sensor can be tested using a
mul-
timeter across its terminals:
/ IAT sensor resistance @ 20" C (68°F) / 2.2 - 2.7 lkCk
~ -- ~~ -
CAUTION--
Be sure ignition is
OFFbefore disconnecting or reconnecting
DME system components.

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Fuel Injection I
- As an alternative, harness connector housing can be sepa-
rated so that electrical
checlts can be made from backof con-
nector.
4 If replacing ECM, disconnect control module harness con-
nector (arrow) by releasing fastener and pivoting connector
up and
off ECM.
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME system components.
- Remove ECM from retaining brackets and lift off holder.
- Installation is reverse of removal.
- Before attempting to start engine, use BMW service tester
DISplus, MoDiC, GTI or equivalent:
- Code replacement ECM with application information (i.e.
engine code, transmission type, etc.).
Align ECM to EWS (electronic immobilizer).
Siemens MS 41.1 ECM pin assignments
ECM pin assignments are given in Table b. For engine man-
agement system schematics, see ELE Electrical Wiring
Di-
agrams.
CAUTION-
a Always wait at least one minute after turning off the ignition
before removing the connector from the
ECM. If the con-
nector is removed before this time, residual power
in the
system relay may damage the
ECM.
Always connect or disconnect the control module con-
nector and meter probes with the ignition
off
When malting checks at the ECM itself, a breakout box
should be used to allow tests to be made with the connector
attached to the ECM. This also prevents damage to the small
terminals in the connector. As an alternative, the harness
connector housing can be separated so that electrical checlts
can be made from the back of the connector.
Table b. Siemens MS
41.1 ECM pin assignments
Pin
1
2
3
4
Signal
output
output
output
qround Componenfffunction
Ignition coil control, cyl. 2
Ignition coil control, cyl. 4
ignition coil control, cyl. 6
Ground Notes
Primary signal,
ignition
coil 2
Primary signal, ignition coil 4
Primary signal, ignition coil 6
Ground