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< Ignition voltage peaks in response to sudden acceleration
load:
1. Normal ignition pattern. Beginning of dying out pattern
is not much higher than ignition voltage peak.
2. Beginning of dying out pattern considerably higher than
ignition voltage peak. Fault in injection system:
Lean fuel mixture
Defective fuel injector
Low compression in cylinder
-, :I 1- i :
Ignition firing order
Normal secondary voltage patterns
(4-cylinder pattern shown).
4 Each ignition coil is mounted above the corresponding spark
plug.
- Number one cylinder is located at the front on 6-cylinder
models.
Number one cylinder is located at the right (passenger side)
front on
V-8 models. Cylinder firing order is shown.
Firing order
M52 - M52 TU - M54 6-cylinder 1-5-3-6-2-4
M62 - M62 TU V-8 1-5-4-8-6-3-7-2
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.-. .
Battery, Starter, Alternator
Warnings and cautions
WARNING -
Wear goggles, rubber gloves, and a rubber apron when
working around the battery or battery acid (electrolyte).
Battery acid contains sulfuric acid and can cause skin
irritation and burning.
If acid is spilled on your skin or
clothing, flush the area at once with large quantities of
water. If electrolyte gets into your eyes, flush them with
large quantities of clean water for several minutes and
call a physician.
Batteries that are being charged or are fully charged
give off explosive hydrogen gas. Keep sparks and open
flames away. Do not
smoke.
CA UTIOI\C
Only use a digital multimeter when testing automotive elec-
trical components.
. If a repair procedure specifies disconnecting the bat-
tery, follow the instruction for safety reasons.
Prior to disconnecting the battery, read the battery dis-
connection cautions in
001 General Cautions and
Warnings.
Models with MS43 engine management: Allow at least
3 minutes to elapse after turning ignition ley to OFFpo-
sition before disconnecting battery. This willallow sum-
cient tinie to complete the DMJL (fuel tank pressure)
test
* Disconnecting the battery cables may erase fault codes
stored in ECM memory.
Always disconnect the negative
(-) battery cable first
and reconnect it last. Cover the battery post with an in-
sulating material whenever the cable is removed.
Do not disconnect battery, alternator or starter wires
while the engine is running.
0 Never reverse the battery cables. Even a momentary
wrong connection can damage the alternator or other
electrical components.
Do not depend on the color of insulation to tell battery
positive and negative cables apart. Label cables before
removing.
The slide-tilt sunroof may fail to function properly
after
disconnecting and reconnecting the battery. Reinitial-
ize sunroof as described in 540 Sunroof.
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Battery, Starter, Alternator
Water-cooled alternator
The water-cooled alternator, used on 1999 and later M62 TU
engines, is a sealed unit housed inside the engine block wa-
ter jacket. It is cooled via the engine cooling system. It is a
"brushless" sealed unit that cannot be serviced. Maintaining
consistent alternator temperatures increases the life span of
the alternator, and elimination of the alternator cooling fan re-
duces alternator noise
significantly.
The M62 TU water-cooled alternator incorporates load start
reduction. This function is intended to shorten the duration of
engine starting, particularly at low ambienttemperatures. The
current load is limited to
20 amps during starting in order to re-
duce alternator braking torque on the engine. Following the
current limiting phase, full power output is then progressively
reached.
Charging system diagnostics requires special test equip-
ment. If the test equipment is not available, charging system
fault diagnosis can be performed by an authorized
BMW
dealer or other qualified repair shop. See Table a. Battery,
alternator and starter troubleshooting for general electri-
cal component troubleshooting.
Before checking the alternator, make sure the battery is fully
charged and capable of holding a charge. Check that the bat-
tery terminals are clean and tight and the alternator drive belt
is properly tensioned and not severely worn.
NOTE-
Some model require up to 15 second to reacli full alternator
output.
CA UTIOG
If the charge indicator light in the instrument cluster remains
on, the charge warning circuit in the instrument cluster may
be faulty. Check that the ground lead is securely
affached to
the grounding stud on the cylinder head
(A). Replacing the
instrument cluster before repairing the ground lead will both
damage the instrument cluster and cause the failure to
reoccur.
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. .
Fuel Injection
Check resistance of valve across valve terminals
Idle speed control valve coil resistance
Terminals
1 and 2 20 i2.0.
Terminals 2 and 3 20 i2.0.
Terminals 1 and 3 40 i4.0.
CAUTIOIG
Be sure ignition is OFFbefore disconnecting or reconnecting
DME system components.
- To remove valve, remove cable bracket mounting bolt and
idle speed control valve mounting bracket bolts from front of
throttle housing and remove idle speed control valve with at-
tached bracket.
NOTE-
When installing idle speed control valve, remove intake boot
sealing ring from valve and install into intake air boot. Then
install valve info sealing
ring.
Evaporative emissions control diagrams
MS 42.0 (LDP) ,-a"-
Evaporative emissions control,
(MS 42.0, MS 43.0)
E39 models with MS 42.0 or MS 43.0 engine are equipped
with a fuel system evaporative pressure leak diagnosis sys-
tem. The main component of this system is the leak diagnosis
pump (LDP or DM-TL). The function of either system is to
pressurize the fuel tank and the evaporative emission system
for the purpose of detecting leaks.
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Fuel Injection
M5.2 system features
The Bosch M5.2 system used on 1997 540i models uses an
88-pin control unit. The
M5.2 system has the following func-
tions and capabilities:
Fully sequential cylinder-individual fuel injection.
Integrated adaptive knock control.
Oxygen sensor fuel mixture control.
0 Self-diagnosis and emergency operation characteristics.
CAN-Bus link.
0 OED II functions (misfire detection, catalytic converter
monitoring, oxygen sensor monitor, and fuel tank ventila-
tion system).
Electronic vehicle immobilization via EWS.
One-touch starter function.
Control of characteristic map thermostat.
M5.2.1 system features
The Bosch M5.2.1 system is used on 1998 540i models. The
M5.2.1 control module utilizes the SKE (standard shell con-
struction housing) with 5 connectors and a combined total of
134 pins.
The M5.2.1 systefn has
tile following functions or capabilities:
Separate power supply relay for ignition coils. Leak diagnosis pump (LDP) control and feedback
rnonitor-
ing for evaporative system leak testing.
Fuel evaporative system providing ORVR (on-board refuel-
ing vapor recovery) compliancy.
Batterylalternator charge logic (idle speed varied with the
battery state of charge).
CAN-Bus communications with the instrument cluster
EWS
Ill "rolling code" ISN interface.
More sensitive ignition
knock sensors.
Pulse width modulated (P-W-M) Heating and
AIC (IHKA)
status signal.
Running loss (312-way) solenoid valve.
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Fuel Tank and Fuel Pump
Fuel pump
The electric fuel pump is mounted in the fuel tank in tandem
with the right side fuel level sender. The fuel pump delivers
pressurized fuel to the fuel injection system.
A pressure regu-
lator maintains system pressure. The quantity of fuel supplied
exceeds demand, so excess fuel returns to the fuel tank via a
return line. See
130 Fuel Injection for more information.
NOTE-
Fuel pump removal procedures are given under Fuel level
sender (right side) and fuel pump, removing and install-
ing.
Fuel tank evaporative control system
Evaporative control, also referred to as running losses con-
trol, is designed to prevent fuel system evaporative losses
from venting into the atmosphere.
The components of this system allow control and monitoring
of evaporative losses by the on-board diagnostic
(OED II)
software incorporated into the engine control module (ECM).
NOTE-
1997 V-8 models (540i) with Bosch DME M5.2 are not
equipped with an
OBD I1 running losses monitoring system.
Fuel tank evaporative
control system
(models with
DME MS42.0)
4 The main components of the evaporative control system and
their functions:
Fuel overflow
tank acts as a liquidlvapor separator
Carbon canister stores evaporated fuel.
Plumbing ducts vapors from fuel tank to canister and from
canister to intake
manifold.
- Carbon canister purge valve is controlled by enginecontrol
module (ECM).
Running losses or 312-way valve (not shown) shunts ex-
cess fuel volume directly
back to fuel tank before it circu-
lates through injector fuel rail (models with Siemens MS42
or Bosch M5.2.1 engine management only).
Leak detection unit (LDP or DMTL) pressurizes fuel
tank
and evaporative system to monitor system leaks (models
with Siemens MS42 or Bosch M5.2.1 and later).
Leak detection systems vary among models and years, and
are further described in
130 Fuel Injection.
NOTE -
"3/2-way valve", 'tunning losses valve" and "fuel changeover
valve" are used interchangeably
in BMW technical literature.
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--
I Fuel Tank and Fuel Pump
The plastic fuel tank is mounted underneath the center of the
car (underneath the rear seat). Mounted in the fuel tank are
the fuel pump and fuel level sending units. Connecting lines
for the evaporative emission control system and expansion
tank are also attached to the tank.
Fuel
tank capacity for E39 models
Tank capacity
70 liters (18.5 gal)
Reserve capacity
8 liters (2.1 gal)
Fuel tank, draining
Drain fuel tank into a safe storage unit using an approved fuel
pumping device.
WARNING-
# Before removing tank, be sure that all hot components,
such as the exhaust system, are completely cooled down.
Fuel may be spilled. Do not smoke or
work near heat-
ers or other fire hazards.
- Start engine and allow to run 10 - 15 seconds to fill fuel com-
pensating siphon assembly. This will allow both lobes of fuel
tank to he drawn off through fuel filler pipe,
- Disconnect negative cable from battery.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
tions.
- Remove fuel tank filler cap
- Slide suction hose into filler neck about 130 cm (51 in.), twist-
ing as necessary. Withdraw fuel into storage unit.
- Monitor fuel level reduction in both lobes:
- Remove rear seat cushion and access both fuel tank send-
er harness connectors.
Use multimeter to measure resistance at both senders,
Resistance should drop as fuel level drops.
- If siphoning mechanism is faulty, drain left tank lobe sepa-
rately by removing sender cover and pumping fuel directly
out of left lobe.
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Fuel Tank and Fuel Pump 1
Activated carbon canister I fuel tank leak
detection unit
(LDP or DMTL), removing . . -
and installing
- Raise rear end of car and support safely.
CAUTION-
Make sure the car is stable and well supported at all times.
Use a professional automotive lift
orjack stands designed for
the purpose.
A floor jack is not adequate support.
- Remove left rear wheel and inner fender panel
Remove carbon canisterlfuel tank leak detection unit
(V-8 model shown):
Disconnect electrical harness connector
(A) from fuel tank
leak detection unit.
Pinch and remove quick-disconnect fittings at intake line to
air filter housing
(5) and hose to expansion tank (C).
* Remove mounting clamp and lower canister with fuel tank
leak detection unit.
Installation is reverse of removal.
Tightening
torques
Hose clamp 8 - 13 mm dia. 2 Nrn (18 in-lb)
Hose clamp
13 - 16 rnm dia 3 Nm (27 in-lb)
Running losses (312-way) valve,
removing and installing
The running losses (312-way) valve is located under the car
beneath the driver's seat, just ahead of the fuel filter. A protec-
tive covershieldsfuel system components from road hazards
and dirt.
The engine control module
(ECM) controls the operation of
the 312-way valve (pulse-width modulated). On engine start
up, the valve solenoid is energized for 20 seconds in order to
supply full fuel volume to the fuel rail.
After20 seconds, the
solenoid is deactivated and sprung closed (the bypass is
opened). This reduces the amount of fuel circulating through
the fuel rail and diverts the excess to return to the fuel tank
through the fuel pressure regulator.
The fuel injectors are supplied with pressurized fuel, but ex-
cess fuel is diverted to the fuel tank without first passing
through the fuel rail. This prevents the excess fuel from ab-
sorbing heat in the engine compartment, thus lowering the
temperature and amount of vaporization in the fuel tank.