1998 BMW 540i Intake removal

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I Fuel Injection
Release injector locking clips at each injector and pry injector
wiring duct up off injectors.
Clamp off fuel supply line and fuel return line at end of fuel
rail. Disconnect fuel supply fuel return lines from fuel rail.
WARNING -
Clamp off the fuel lines and then wrap a clean shop towel
around the lines before removing them. Residual
fuelpres-
sure is present in the lines.
Fuel is discharged. Do not disconnect any wires that
could cause electrical
sparks. Do not smoke or work
near heaters or other fire hazards. Keep an approved
I fire extinguisher handy. I
- Remove fuel rail mounting fasteners
- Pull up on fuel rail and remove individual injectors by remov-
ing injector retaining clip and pulling injector from rail.
- Installation is reverse of removal. Fit new O-rings when in-
stalling injectors. For ease of installation, lightly lubricate in-
jector O-ring with
SAE9O gear lube.
Tightening torque Fuel rail to
intake manifold 10 Nm (89 in-lb)
Evaporative emissions, overview
On E39 MS 41 .I cars, the evaporative emissions system is
combined with the tank ventilation system. The evaporative
system is monitored by the ECM for correct purge operation
and leak detection.
The carbon (purge) canister is purged using engine vacuum
via the
purgevalve.The purgevalve (located nextto the mass
airflow sensor) is ECM controlled and regulates the purge
flow into the intake manifold. The valve is powered open and
closed by an internal spring.
If the evaporative emission valve circuit is faulty, a fault code
is set and the MIL is illuminated when OBD
II fault criteria are
exceeded. If the valve is mechanically faulty, poor driveability
may result and a mixture adaptation fault is stored in the
ECM.
The leak diagnosis pump (LDP) is activated by the ECM and
pressurizes the fuel tank and evaporative system as apart of
theOED I1 leakdetection monitor. If the LDP orthe LDP circuit
is defective, afault code is set and the MIL is illuminated when
OBD
I1 fault criteria are exceeded. The LDP is mounted the
left rear wheel well behind the fender liner.

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Fuel Injection
A faulty MAF sensor can produce the following problems:
Difficult to restart when engine is hot
Engine starts then stalls
* Engine starts and runs only with accelerator pedal de-
pressed
4 Disconnect electrical harness connector from MAF sensor
(B).
- Turn ignition on and checlc for voltage and ground at connec-
tor.
There should be ground at pin
1 and battery voltage at pin
3.
- If any faults are found, checlc for wiring breaks between
MAF sensor and ECM and between MAF sensor and main
DME relay.
NOTE-
Visually inspect the sensor for damage, missing or blocked
screens. The screens affect air flow calibration. Also inspect
the sealina
0-rinas where the sensor inserts into the air filter - - housing and intake boot. Ensure the pin connections are
clean and tight.
4 Connect a BMW-compatible scan tool or an OED II generic
scan tool.
Checlc air mass signal (load signal) with the engine
at idle. Raise idle speed and
checlc that load signal changes
with rpm.
CAUTION-
Be sure ignition is OFFbefore disconnecting or reconnecting
DME system components.
Remove MAF sensor:
Loosen intake boot clamp
(A).
Disconnect harness connector (6).
* Release clip from air filter housing (C) and remove sensor.
- Installation is reverse of removal.
No adjustment to MAF sensor is possible.
Check intake hoses for cracks and vacuum
lealts.

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Fuel Injection
Engine coolant temperature
(ECT) sensor,
testing and replacing
4 The ECT sensor is located below cylinder 6 intake port at the
rear of the engine (1).
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
forthe engine temperature by monitoring an
appliedvoltage
(5vdc) to the sensor.Thevoltage drop across
the sensor varies as the coolant temperature (sensor resis-
tance) changes.
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 the MIL is illuminated when
OED II fault crite-
ria are exceeded. The ECM assumes a substitute value
(80" C 11 76'F) to maintain engine operation. The ignition tim-
ing is set to a
conservativelsafe basic setting.
- Remove intake manifold to access ECT sensor on the M52
TU and the M54 engines. See 113 Cylinder Head Removal
and Installation.
- Check ECT sensor resistance using a multimeter at sensor
terminals.
WARNING -
Due to rislc of personal injury, be sure the engine is cold be-
fore removing ECT sensor connector.
ECT sensor resistance @ 20°C (68°F)
CAUTIOI\C
Be sure ignition is OFFbefore disconnecting or reconnecting
DME svstem components.
2.2 - 2.7 k
4 Disconnect ECT sensor harness connector (arrow). Un-
screw ECT sensor from cylinder head.

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Fuel Injection
- Installation is reverse of removal:
Use new copper sealing washers when installing sensor.
Replace any lost coolant.
Tightening torque
Temperature sensor to cylinder head
13 Nm (10 ft-lb)
Intake air temperature (IAT) sensor,
testing and replacing
4 The intake airtemperature (IAT) sensor, located at the top of
I the intake manifold, adapts (fine tunes) the fuel mixture and i
T engine timing based on varying intake air temperatures.
i If the intaite air temperature signal is implausible, a fault code
! is set and the MIL is illuminated when OBD I1 fault criteria are
I exceeded. The ECM then operates the engine using the ECT
i sensor sional inout as a back uo.
type sensor. In other words,
a> the temperature rises, resis-
tance through the sensor decreases.
lid I The IATsensor can be tested using a multimeter:
/IAT sensor resistance at 20'C (68°F) 2.2 - 2.7 kd
Remove engine cover by prying off plastic trim caps (arrows)
and removing nuts below caps.

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Fuel Injection
4 Remove electrical harness connector (arrow) from IAT sen-
sor.
CAUTION-
Be sure the ignition switch is in the off position before repiac-
ins the intake temperature sensor.
- Depress loclting clip on side of temperature sensor and pull
straight out of intake manifold.
- Installation is reverse of removal
- Use a new sealing O-ring at base of sensor and lubricate with
assembly lubricant for
ease of installation
MS 42.0 throttle valve assembly, replacing
< The motor driven throttle valve for the MS 42.0 system is re-
- ferred to as MDK (motor driven throttle valve). The MDK unit
is electronically operated to regulate intake air flow by the
ECM.
The
MS 42.0 system uses a throttle cable from the accelera-
tor pedal to the MDK unit. The throttle cable is connected di-
rectly to the integral pedal position sensor
(PWG) in the MDK
unit. This sensor communicates pedal position to the ECM,
which in turn electronically regulates throttle plate position.
The MDK pulley is linked to the throttle shaft by springs to al-
low ASC intervention to override the driver's pedal position.
NO TE -
The MDIC unit is non-adjustable and must be replaced as
a complete unit if found to be faulty.
if replacing the
MDK unit, the adaptation values stored in
the ECM must be clearedand the new unit initialized using
BMW special service tools.
CAUTION-
If the adaptation process is not completed correct& the en-
gine wiii
not start.
- Disconnect battery negative (-) cable in luggage compart-
ment.
CAUTION-
Prior to disconnecting the battern read the battely discon-
nection cautions in
001 General Warnings and Cautions.

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/Fuel Injection
4 Remove dipstick guide tube:
Disconnect wiring harness brackets from tube (A).
Unclip fuel lines from dipstick tube
(El).
Remove lower guide tube mounting bolt (C). Pull out dip-
stick guide tube.
< If necessary, disconnect electrical harness connector at fuel
tank venting valve (A). Disconnect hose at quick disconnect
fitting (arrow).
Working at throttle housing, turn harness plug counterclock-
wise and disconnect. Remove throttle assembly mounting
fasteners (arrows) and pull assembly off manifold.
Installation is reverse of removal
Replace sealing ring between throttle assembly and intake
manifold.
0 Reattach throttle assembly harness connector with care.
Arrow on fully tightened connector must line up with corre-
sponding arrow on throttle assembly housing.
* Connect BMW test equipment or equivalent and carry out
throttle plate adaptation following the on-screen directions.
Reattach throttle cable and check cable adjustment as de-
scribed under Throttle cable, adjusting
(MS 42.0).

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-.
Fuel Injection 1
4 If necessary, disconnect electrical harness connector at fuel
tank venting valve (A). Disconnect hose at quick disconnect
fitting
(arrow).
< Worlting at throttle housing, turn harness plug counterclock-
wise and disconnect. Remove throttle assembly mounting
fasteners
(arrows) and pull assembly off manifold.
- Installation is reverse of removal.
0 Replace sealing ring between throttle assembly and intake
manifold.
Reattach throttle assembly harness connector with care.
0 Arrow on fully tightened connector must line up with corre-
sponding arrow on throttle assembly housing.
- Use BMW scan tool to reset ECM adaptation values.

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Fuel Injection I
4 Release spring clips (arrows) from fuel injectors and pull in-
jector electrical loom straight up to remove.
4 Check that ECM signal is present at injector connectors.
- Connect digital voltmeter to fuel injector harness plug.
Operate starter and
check for voltage pulse.
* Repeat for each injector.
- Remove fuel injectors by removing retaining clips
- Installation is reverse of removal:
Fit new O-rings when installing injectors. For ease of instal-
lation, lightly lubricate all fuel system O-rings with assem-
bly lubricant.
Check that injector electrical connections are correctly fit-
ted and that
injectors are fully seated prior to installing iuel
rail mounting bolts.
Mass air flow sensor (MAF), replacing
The MAF sensor is provided with operating power from the
ECM relay. Based on calculated intake air mass, the MAF
generates
avarying voltage (approx. 0.5 - 4.5 vdc) as an input
signal to the ECM.
4 Remove MAF sensor:
Remove upper air filter housing locking clips.
Unscrew and remove MAF sensor harness
(A).
Disconnect intake air temperature sensor harness (B).
Loosen hose clamp (C).
Remove upper filter housing with sensor.
- Installation is reverse of removal