1998 BMW 540i top speed

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Maintenance
< Remove NC compressor belt:
Loosen tensioner mounting fasteners (arrows)
Swing tensioner down to remove belt.
4 To reinstall compressor belt:
Route belt over pulleys.
* Pretension belt by turning adjuster clockwise (arrow) to
stop.
- Tighten tensioner mounting bolts (A).
Tightening torques
Fan clutch to coolant pump (left- hand thread)
with BMW tool
11 5 040
30 Nm (22 ft-lb)
without BMW tool 11 5 040
40 Nm (29 ft-lb)
Tensioner to engine block
8.8 grade
22 Nm (16 ft-lb)
10.9 grade (Ilquid-cooled alternator) 30 Nm (22 ft-lb)
Idle speed
Engine idle speed can change due to a number of factors, in-
cluding normal wear. The idle speed is electronically adaptive
and not adjustable. See
130 Fuel Injection for more informa-
tion.
Catalytic converter and oxygen sensors
OBD II enhanced emission standards require the engine
control module (ECM) to monitor the oxygen content in the
exhaust with oxygen sensors placed before and after the cat-
alytic converter. This allows for tighter control of tail pipe
emissions and also allows the ECM to diagnose converter
problems. If the ECM detects that catalytic converter or oxy-
gen sensor efficiency has degraded past a certain
prepro-
grammed limit, it will turn on the malfunction indicator light
(MIL), and store a diagnostic trouble code (DTC) in the ECM.
See OBD On-Board Diagnostics for more information on
OBD
ll systems.
Replacement of oxygen sensors at the specified intervals
he engine and emission control system will

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11 0-4
/Engine Removal and Installation
- Disconnect negative (-) cable from battery.
CAUTION- Prior to disconnecting the
batteg read the battery discon-
nection cautions
in 001 General Cautions and Warnings.
- Remove engine hood, or place in service position. See 410
Fenders, Engine Hood.
4 Remove left and right interior ventilation ducts (lefl side
shown):
Release ventilation filter cover latch (A) and remove cover.
Release plastic loclting tab
(6) or release locking tabs on
top of duct (later models).
Rotate duct counterclocltwise to
unloclt from bulkhead and
remove (arrow).
Disconnect electrical harness from hood switch (C).
Release spring
loclt (D).
Slide filter housing away from inner fender to remove.
Removal of right side ventilation duct is similar.
Remove rear bulkhead panel:
Remove rubber sealing gasket (arrow).
- Remove 3 mounting clips (A).
Remove
4 retaining screws (6).
Lift off panel.
Remove complete air filter housing:
Loosen
intalte duct hose clamp (A) at throttle assembly.
Loosen clamp and remove idle control line from intalte duct
(6) and (where applicable) disconnect idle speed control
valve electrical harness connector.
Disconnect harness connector (C) from mass air flow sen-
sor.
Remove air filter housing mounting screw (D).
Disconnect vent tube
(E).
Loosen air intake duct clamp (F).
Carefully lift air filter housing out of engine bay.

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11 3-9
Cylinder Head Removal and Installation
< Remove left and right interior ventilation ducts (left shown):
Release ventilation filter cover latch (A) and remove cover.
Release plastic locking tab
(6) or release locking tabs on
top of duct (later models).
Rotate duct counterclockwise to unlock from bulkhead and
remove (arrow).
Disconnect electrical connector from hood switch
(C).
Release spring lock (D).
Slide filter housing away from inner fender to remove.
Removal of right side ventilation duct is similar.
Remove rear bulkhead panel: Remove rubber sealing
gasket (arrow).
0 Remove 3 mounting clips (A).
Remove
4 retaining screws (6).
Lift out panel.
< Remove complete air filter housing:
Loosen
intake duct hose clamp (A) at throttle assembly.
Loosen clamp and remove idle control hose from
~ntake
duct (6) and disconnect Idle speed control valve electr~cal
harness connector.
Disconnect
electr~cal harness connector (C) from mass alr
flow sensor.
Remove air filter housing mounting screw (D).
Disconnect vent tube
(E).
Loosen air intake duct clamp (F).
Carefully lift air filter housing out of engine bay.
4 Remove positive battery cable and intake manifold cover:
Remove protective cover from positive (+)jumper post (A).
Loosen and remove battery lead mounting nut.
Remove battery lead and push down through intake mani-
fold.
Remove trim caps (arrows) from fuel injector cover.
Remove cover hold down fasteners and lift off cover.

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ignition System
Crankshaft speed sensor, replacing (M62 and M62TU
engines)
The crankshaft speed sensor reads a toothed pulse wheel
mounted on the flywheel.
If the Engine Control Module(ECM)
does not receive an impulse signal from the crankshaft speed
sensor during
cranking, the engine will not start. If the OBD II
system misfire detection protocol detects a catalyst damag-
ing fault due to a malfunction in the crankshaft speed sensor
components, the Check Engine light (Malfunction
Indicator
Light or MIL) will be Illuminated.
4 The crankshaft speed sensor (arrow) is mounted in the right
lower side of the bell housing.
- Remove speed sensor by disconnecting electrical harness
connector and unbolting sensor from bell housing. Do not
discard shims, if present.
- Installation is the reverse of removal. Clean mounting surface
before installing new sensor, and install shims, if present.
< If the flywheel was replaced, the speed sensor must be
checked for correct installation depth.
* Crank engine in direction of rotation using crankshaft bolt
until a full pulse tooth is centered in the opening for the re-
moved speed sensor.
Measure depth ro top of tooth from speed sensor p~lse
generator mounting s~rface on transmission.
4 Measure length of pulse generator from mounting surface to
end (A).
- Subtract length of pulse generator (A) from distance to pulse
tooth from mounting area on transmission. This measure-
ment is the gap between the pulse sensor and flywheel. Use
shims available from BMW to increase gap as needed to
reach specification.
Pulse sensor
gap
End of sensor to flywheel teeth 0.55 + 0.2 rnrn
(0.0217 t 0.008 in)

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Fuel Injection
- If idle speed valve is not buzzing, or if idle decreases when
AIC is turned on, stop engine and disconnect harness con-
nector from idle speed valve.
connector
CAUTION-
Be sure ignition is OFFbefore disconnecting or reconnecting
DME system components.
Checlc resistance of valve across valve terminals.
Idle speed control valve resistance
Terminals
1 and 2 20 i-2Q
Terminals 2 and 3 20 C2Q
Terminals 1 and 3 40 C4Q
The idle speed control valve is mounted under the intake
manifold. Accessing the valve is best accomplished by first
removing the air filter housing and the throttle housing.
< Disconnect intake air boot from throttle housing. Unbolt throt-
tle body and lay aside. Do not disconnect throttle cable or
electrical harness connectors to throttle body.
NOTE-
For additional worlcing room, unfasten and lift out the com.
plete air filter housing.
- Working under intake manifold, disconnect electrical harness
connector from idle speed control valve.
Unbolt dipstick tube
bracket (A) from intalte manifold.
- Remove two bolts (B) retaining idle speed control valve to un-
derside of intalte manifold. Remove valve from intalte mani-
fold. Remove hose clamp and disconnect hose.
- Installation is reverse of removal. Use new gaskets when in-
stalling.

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130-38
Fuel Injection
Throttle cable, adjusting
(MS 42.0)
The throttle assembly on MS 42.0 cars uses a throttle cable.
The cable should be adjusted any time it is disconnected or
replaced. This procedure requires the factory scan tool or an
equivalent to read and adjust throttle angle. It is recommend-
ed the procedure be done by an authorized
BMW dealer ser-
vice department
Basic adjustment:
Ensure that at idle (accelerator pedal in rest position) throt-
tle cable has detectable play at throttle lever attaching
point. Play must not exceed maximum allowable.
Adjust by turning knurled adjuster
(arrow) on end of throt-
tle cable sheath at throttle housing.
NOTE-
Faulty throttle adjustment values must be reset using the
BMW service tester
DISplus, MoDiC, GTI or equivalent.
Max.
play at throttle plate lever
ldle speed control valve,
checking and replacing
3 mm (0.125 in)
The Idle speed control valve regulates Idle speed by red~rect-
ing air around the throttle valve. The ldle speed control valve
is mounted
d~rectly above the throttle housing. Accessing the
valve is best accomplished by
flrst removing the air fllter
housing and associated ducting.
Thevalve is supplied with batteryvoltage from the ECM relay.
The idle speed control valve incorporates a two-coil rotary ac-
tuator. The ground sides of each coil are pulsed simulta-
neously by the ECM. The duty cycle of each circuit is varied to
achieve the required idle speed.
A faulty idle speed control valve sets a fault code and the MIL
is illuminated when
OED II fault criteria are exceeded.
Before checking the idle speed control valve, confirm that the
throttle position sensor is working correctly.
- With engine running, check that idle speed control valve is
buzzing.
- Turn on AIC system or shift transmission into drive. ldle
should remain steady or increase slightly.
- If idle speed valve is not buzzing, or if idle decreases when
AIC is turned on, stop engine and disconnect harness con-
nector from idle speed valve.

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130-54
I Fuel Injection ldle speed control valve,
testing and replacing
ldle speed is maintained by the ECM through the idle speed
control valve. The idle control function compensates for en-
gine load and engine operating conditions. ldle speed is
adaptive through the ECM and no adjustments can be made.
Before checking valve, confirm that throttle position sensor is
working correctly.
NOTE-
The test given below is an electrical check only. It does not
check the mechanical operation of the valve. If the valve is
sticking, hanging up or is sluggish in operation, substituting a
Inown good valve is the best way to check it.
With engine running, check that idle speed control valve is
buzzing.
Turn on
AIC or shift car into drive. ldle should remain steady
or increase slightly.
If valve is not buzzing, or if idle decreases in step above, stop
engine and disconnect harness connector from valve.
4 Check resistance of valve across its terminals. Test values
are listed below.
ldle speed control valve coil resistance
Terminals
1 and 2 20 +2%
Terminals 2 and 3 20 +2Q
Terminals 1 and 3 40 +4%
NOTE-
If you suspect an intermittent fault, lightly tap the valve while
testing resistance.
With valve harness connector disconnected, check for bat-
tery voltage at redlwhite wire in connector with ignition on.
If . ~~ ~~
there is no voltage, check wiring between connector and 7 ECM relay. See ELE Electrical Wiring Diagrams.
NOTE- - The idle speed control valve receivespositive (+) battery volt-
age from the ECM (DME main) relay

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Clutch
Clutch, installing (used SAC components)
When reinstalling a previously used self-adjusting clutch
(SAC), special tools are needed to reset the self-adjusting
ring to its original position.
CAUTIOI\C
Avoidcontaminating clutch friction suifaces with oilorgrease.
Do not touch these
suifaces.
- Place SAC pressure plate on clean worlc suriace.
4 Place BMW special tool 21 2 180 on pressure plate
Note that locating hoolts of special tool engage pressure
plate adjusting ring openings
(inset).
Grip tool firmly and squeeze special tool handles together.
Tighten down special tool knurled screws (arrows).
- SAC adjustment ring is now in its original position.
4 Install BMW special tool 21 2 170 on SAC pressure plate.
Fit fingers of special tool in slots above dowel pin bores.
Tighten down knurled nut (arrow) finger-tight.
Screw in T-handle until pressure plate diaphragm spring is
pretensioned to stop.
< Center clutch disc on flywheel using centering tool.
5-speed transmission: Special tool 21 2 142
6-speed transmission: Special tool 21 2 141
G6S-3762 transmission: Special tool 21 2 201
CAUTION--
Be sure clutch disc is lacing the correct way The disc should
be
marked 'kngine side" or 'Transmission side':
NOTE-
The large bolt in the clutch disc centering tool is used to in-
stalland remove the tool only Once the disc is in place on tlie
flywheel, remove the bolt to male room for the SACpressure
plate.