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Battery, Starter, ~lternatorl
Alternator, removing and installing
(6-cylinder engine)
A replacement alternator should have the same rating as the
original. Alternator manufacturer and ampere rating are nor-
mally marked on the alternator housing.
- Disconnect negative (-) battery cable.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
I tions.
Remove complete air filter housing:
Loosen intake duct hose clamp
(A) at throttle assembly.
Loosen clamp and remove idle control hose from intake
duct
(B) and disconnect idle speed control valve electrical
harness connector.
Disconnect electrical harness connector
(C) from mass air
flow sensor.
* Remove air filter housing mounting screw (D),
Disconnect vent tube (E).
Loosen air intake duct clamp (F).
Carefully lifl air filter housing out of engine bay.
Remove alternator drive belt. See belt removal procedures in
020 Maintenance.
- Remove radiator cooling fan and fan shroud. See 170 Radi-
ator and Cooling System.
NOTE-
The radiator cooling fan nut (32 mm wrench) has left-hand
threads.
- Unbolt power steering fluid reservoir and bracket. Suspend to
one side without detaching fluid hoses.
- Disconnect alternator air cooling tube.
- Disconnect wiring from rear of alternator.
'4 Remove upper and lower mounting bolts (arrows) and lift
alternator.
If idler pulley for belt interferes, remove pulley cover and
retaining bolt to remove pulley. out
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I Battery, Starter, Alternator
- Check for battery voltage at terminal 50 of starter motor with
key in start position. If voltage is not present, check wiring be-
tween ignition switch and starter terminal. Check the EWS
system and other inputs that disrupt terminal
56 to the start-
er. See ELE Electrical
Wiring Diagrams. If voltage is
present and no other visible wiring faults can be found, prob-
lem is most likely in starter motor.
Starter, removing and installing
(6-cylinder engine)
The starter is removed from below. Access to starter bolts is
difficult. Be sure to have the proper tools on hand before pro-
ceeding.
NOTE-
Access to the starter wiring is very limited. Forbetteraccess,
it may be necessary to remove the intake manifold.
- Disconnect negative (-) battery cable.
CAUTIOI\C
Prior to disconnecting the battern read the baltery discon-
nection cautions
in OOlGeneral Cautions and Warnings.
Remove complete air filter hous~ng:
Loosen intake duct hose clamp (A) at throttle assembly.
Loosen clamp and remove idle control hose from intake
duct
(B) and disconnect idle speed control valve electrical
harness connector.
Disconnect electrical harness connector
(C) from mass air
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.
Disconnect throttle cable.
Raise vehicle and support safely.
WARNING-
Make sure the car is stable and well supported at all times.
Use a professional automotive
lift orjack stands designed for
the purpose. A
floorjaclc is not adequate support
- Working underneath car, remove engine splash shield
- Disconnect fuel lines and harness connectors from retaining
brackets, as necessary.
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130-1
130 Fuel injection
General ........................... .I3 0.2
Tools and test equipment .............. .I3 0.3
Warnings and cautions ................ .I3 0.5
Fuel Supply ....................... .I3 0.6
Relieving system fuel pressure .......... .I3 0.6
Siemens MS 41 . 1. ................... 1 30-7
ECM relay. testing .................... .I3 0.7
Mass air flow (MAF) sensor.
checking and replacing
................ .I3 0.9
Engine coolant temperature (ECT) sensor.
testing and replacing
.................. 130-10
Intake air temperature (IAT) sensor.
testing and replacing
................. .I3 0.1 1
Throttle position sensor (TPS).
testing and replacing
.................. 130-1 2
ldle speed control valve.
checking and replacing
............... .I3 0.1 3
Fuel injectors. checking and replacing .... 130-15
Evaporative emissions. overview ....... .I3 0.1 6
Secondary air injection. overview ....... .I3 0-17
Engine control module (ECM).
removing and installing
................ 130-18
Siemens MS 41.1 ECM pin assignments . .I3 0.19
Siemens MS 42.0 and MS 43.0. ..... .I3 0.23
ECM relay. testing ................... .I3 0.27
Mass air flow (MAF) sensor.
checking and replacing
............... .I3 0.28
Engine coolant temperature (ECT) sensor.
testing and replacing
................. .I3 0.30
Intake air temperature (IAT) sensor.
testing and replacing
................. .I3 0.31
MS 42.0 throttle valve assembly. replacing . 130-32
MS 43.0 throttle valve assembly. replacing . 130-35
Throttle cable. adjusting (MS 42.0) ...... .I3 0.38
ldle speed control valve. checking
and replacing
....................... .I3 0.38
Evaporative emissions control diagrams . . 130- 39
Evaporative emissions control.
(MS
42.0 and MS 43.0). .............. .I3 0.39
Engine control module (ECM).
removing and installing
................ 130-40
Siemens MS 42.0 and MS 43.0
ECM pin assignments ................. 130-41
Bosch M5.2 (M62 up to 911997)
BOSC~ M5.2.1 (M62 911997 to 911998) 130-46
M5.2 system features ................. 130-47
M5.2.1 system features ............... 130-47
ECM relay. testing ................... 130-49
Oxygen sensors. checking ............. 130-51
Fuel injectors. checking and replacing .... 130-52
Mass air flow (MAF) sensor. replacing .... 130-53
ldle speed control valve. testing
and replacing
....................... 130-54
Throttle position sensor (TPS).
testing and replacing
................. 130-55
Engine coolant temperature (ECT) sensor.
testing and replacing
................. 130-55
Intake air temperature (IAT) sensor.
testing and replacing
................. 130-57
Auxiliary throttle valve (ADS) (M62 and
M62 TU engine). replacing ..... 130-57
Evaporative system pressure
leak diagnosis. overview
(5.2.1 only) ..... 130-58
Bosch 5.2 ECM pin assignments
(M62 UP to 911 997) ................... 130-59
~osch 5.2.1 ECM pin assignments
(M62 911 997 to 911 998) ............... 130-62
BOSC~ ME 7.2 ..................... 1 30-66
ME 7.2 system overview ............... 130-67
EDK adaptation ..................... 130-69
ECM relay. checking .................. 130-69
Engine coolant temperature
(ECT) sensor. testing
................. 130-71
Engine coolant temperature
(ECT) sensor. replacing
............... 130-71
Oxygen sensors. replacing ............. 130-72
Fuel injectors. removing and installing .... 130-72
Mass air flow (MAF) sensor.
removing and installing
................ 130-73
Evaporative system pressure
leak diagnosis. overview
............... 130-74
Secondary air injection. overview ........ 130-75
Bosch ME 7.2 ECM pin assignments .... 130-76
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Fuel Injection I
Mass air flow (MAF) sensor,
checking and replacing
4 The hot film mass air flow (MAF) sensor (arrow) sends a
varying voltage (approx.
0.5 - 4.5 vdc) to the ECM represent-
ing the measured intake air. The air mass input signal is pro-
duced electronically by the
MAFsensorusing a heated metal
film in the air flow stream.
The ECM relay provides the operating voltage to the MAF
sensor. As air flows through the MAF sensor, the film is
-
cooled. To maintain the film at a constant temperature, addi-
tional heating current is necessary. It is this additional current
that is the basis for the input signal.
If there is no output signal from the MAF sensor, the ECM op-
erates the engine using throttle position and engine rpm in-
puts. A faulty MAF sensor illuminates the MIL.
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.
Disconnect electrical harness connector from MAF sensor
(arrow).
- Turn ignition on and check 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, check for wiring breaks between
MAF sensor and ECM and between MAF sensor and ECM
relay.
NOTE-
Visually inspect the sensor for damage, missing or blocked
screens. The screens affect air flow calibration. Also inspect
the sealing O-rings 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 OBD II generic
scan tool. Check air mass signal (load signal) with the engine
at idle. Raise idle speed and check that load signal changes
with rpm.
CA UTIOI\C
Be sure ignition is OFFbefore disconnecting or reconnecting r
1 DME svstem components. 1
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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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130-1 2
Fuel Injection
- Disconnect intake air boot from throttle housing. Unbolt throt-
tle housing and lay aside. It is not necessary to disconnect
throttle cable or electrical harness connectors from throttle housing.
- Remove electrical harness connector from IAT sensor.
- Unclip temperature sensor and remove from intake manifold.
- Installation is reverse of removal. Use a new gasket at throttle
housing.
Throttle position sensor (TPS),
testing and replacing
4 The throttle position sensor (arrow) is located on top of the
throttle valve housing and provides the ECM with a voltage
value that represents throttle position (angle) and rate of
movement.
TheTPS is non-adjustable. If the throttle position sensor is re-
placed, the previous 'learned' TPS settings must be cleared
from the ECM using a BMW-compatible scan tool.
If the throttle position sensor signal is defective, afault code is
stored and the
MILis illuminated when OBD II fault criteria are
exceeded. The ECM still operates the engine using the mass
air flow
(MAF) sensor and engine rpm inputs.
- Check throttle position sensor function by disconnecting har-
ness connector and checking continuity across terminals. If
test results are incorrect,
replace throttle position sensor. The
sensor is non-adjustable.
Throttle
~osition sensor testina values -
Terminals Test
values
1 and ground in harness 5 vdc (approx.)
connector, ltey on
1 and 3 at sensor 4.0 itR(appr0x.)
1 and 2 at sensor Throttle
plate rotated from idle to
lull throttle, continuously variable
from 1.0
- 4.0 1tR
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME svstem components. r
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130-1 3
Fuel Injection I
< Unplug harness connector (arrow) from sensor.
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME system components.
NOTE-
Do not confuse the throttle position sensor on the main Nirot-
tle body with the throttle position switch on the secondary
throttle body, where applicable.
- Remove two mounting screws holding sensor to throttle
housing.
- Installation is reverse of removal. Clear adaptation settings
from ECM using BMW-compatible scan tool.
NOTE-
Poor idle quality may be noticeable for a period if the adapta-
tion settings are not cleared after installing new TPS.
ldle speed control valve,
checking and replacing
The idle speed control valve regulates idle speed by redirect-
inq airaround the throttlevalve.The idlespeed control valve is
mounted on the underside of the intake manifold adjacent to
the dipstick tube bracket. Accessing the valve is best accom-
plished by first removing the air filter housing and the throttle
body assembly.
The valve issupplied with
batteryvoltagefrom the ECM relay.
The idle speed control valve incorporates a two-coil rotary ac-
tuator. The ground sides of each coil are pulsed
sirnulta-
neously by the ECM. The duty cycle of each circuit is varied to
achieve the required idle speed.
Afaulty ldle speed control valve sets afault 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.