2001 BMW 540i air flow sensor

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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
Warnings and cautions
For personal safety, as well as the protection of sensitive
electronic components, adhere to the warnings and cautions
on the following pages.
WARNING-
Gasoline is highly flammable and its vapors are explosive.
Do not smoke or work on a car near heaters or other fire
hazards when diagnosing and repairing fuel system prob-
lems. Have a fire extinguisher available in case of an emer-
gency
Renew fuel system hoses, clamps and O-rings any
time they are removed.
When working on an open fuel system, wear suitable
hand protection, as prolonged contact
with fuel can
cause illnesses and skin disorders.
* 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.
CAUTION-
- Disconnecting the battery may erase fault code($ storedin
memory Check for fault codes prior to disconnecting the
battery cables. Read the battery disconnection cautions in
001 General Warnings and Cautions.
a Connect and disconnect the DME system wiring and
1 test equipment leads only when the ignition is switched
off.
Wait at least 1 minute after turning off the ignition be-
fore removing the engine control module (ECM) con-
nector. If the connector is removed before this time,
residualpower in the system relay may damage the
control module.
Fuel system cleaners and other chemical additives oth-
er than those specifically recommended by BMW may
damage the catalytic converter, the oxygen sensor or
other fuel supply components.
* Do not connect any test equipment that delivers a 12-
volt power supply to terminal 15 (+) of the ignition coil.
The current flow may damage the ECM. In general,
connect test equipment only as specified by BMW or
the equipment maker.
Only use a digital
multirneter for electrical tests. Only
use an LED test light for
quiclc tests.

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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 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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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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I Fuel Injection
Table b. Siemens MS 41.1 ECM pin assignments (continued)
Pin
l~iqnal I Componentlfunction 1 Notes I - I I
5 loutput I Fuel injector control, cyl. 2 I Pulsed ground (pulse width in ms), cyl. 2 I I I
6 loutput /Fuel injector control, cyi. 1 I Pulsed ground (pulse width in ms), cyl. 1
I I I
14 linput I Intake air temp. sensor (IAT) I Intake air temperature signal
- 7
8
9
10
11
12
13
ground
input
output
input
input
15
16
17 18
19
20
21
22
I - I I
35 loutput /Secondary air injection ISecondary air inj. pump relay control
25
26
27
28
29
30
31
32
33
36
/output I Engine speed output IEngine speed signal
Mass air flow sensor
Mass air flow sensor
instrument cluster
Engine coolant
temp.
(ECT) sensor
Not used
Throttle position sensor (TPS)
Not used
input
input
input
input
output
output
out~ut
37 1 - /Not used I
Mass air flow sensor signal
Mass air flow sensor signal
Fuel consumption signal
ECT signal
Throttle position signal
ground
input
output
ground
output
output
output
ground
output
Traction control (rear engine speed signal) Automatic climate control
Not used Electronic immobilizer control (EWS)
Auto. climate control
(AIC on input)
instrument
cluster
Camshaft actuator control (VANOS)
Fuel iniector control, cvl.
3
AES/ASC module
Automatic climate control instrument cluster (CARE signal)
Camshaft actuator (VANOS), switched ground
Pulsed ground (pulse width in
ms), cyl. 3
Oxygen sensor heater (no. 1 in front of catalytic
converter)
Power supply (terminal
30)
Idle speed control valve
Ground
Ignition coil control, cyl.
1
Ignition coil control, cyl. 3
Ignition coil control, cyl. 5
Ground Fuel injector control, cyl.
5
Oxygen sensor heater ground
Battery voltage
(E+) at all times
Pulsed ground-open signal (See pin
53)
Ground
Primary signal, ignition coil
1
Primary signal, ignition coil 3
Primary signal, ignition coil 5
Ground
Pulsed ground (pulse width in ms), cyl
5

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- -.
Fuel Injection
SIEMENS MIS 42.0 AND 43.0
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also illuminates
if an emissions-related fault is detected.
When faults arise, or
if the malfunction indicator lamp (MIL) is
illuminated, begin troubleshooting by connecting BMW ser-
vice tester
DISplus, MoDiC, GTI or equivalent scan tool. The
capabilities of OBD
II software has the potential to save hours
of diagnostic time and to help avoid incorrect component re-
placement and possible damage to system components.
CAUTION-
* The tests in this section may set fault codes (DTCs) in tlie
ECM and illuminate the MIL. After all testing is completed,
access and clear DTC fault
memory using an OBD I/ or
BMW compatible scan tool. See
OBD On-Board Diag-
nostics.
Only use a
dgital multimeter for electrical tests.
Relay positions can vary. Be sure to confirm
relayposi-
tion by identifying the wiring in the socket using the wir-
ing diagrams found in
ELE Electrical Wiring
Diagrams.
NOTE-
- OBD I1 fault memory. (including an illuminated MIL! can
only be reset using the special scan tool. Removing the
connector from the ECM or disconnecting the battery will
not erase the fault memory.
The BMW-dedicated 20-pin diagnostic
linlc connector
(DLC) is in the right rear of the engine compartment The
20-pin DLC is discontinued on models after
6/2000.
The 1 &pin OBD I1 diagnostic connector (arrow) is located
inside the car on the lower left dash panel.
The MS
42.0 and MS 43.0 systems manage the following
functions.
- Air:
Idle speed valve
Electronic throttle
Hot film mass air flow (MAF) sensor
Resonance-turbulence intake control
- Fuel:
* Fuel supply
Running losseslnon return
Fuel injection

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-
Fuel Injection
ECM relay, testing
The engine control module (ECM) relay is energized via the
ECM and supplies battery positive
(Bc) power to many of the
engine management components and subsystems. If this re-
lay is faulty, the engine will not start.
NOTE-
The ECM relay is also referred to as the DME main relay
ECM relay powers:
ECM
Ignition coils
* Fuel injection
Evaporative leak detection pump
Idle air actuator
- Camshaft sensors Evaporative emissions valve
Hot film mass air flow sensor
Fuel pump relay
Oxygen sensor heaters
4 Working in right rear of engine compartment:
Release interior ventilation filter cover latch
(A) and re-
move cover.
Release plastic locking tab
(B).
Rotate duct inward (arrow) to unlock from bulk head and
remove duct.
Release spring lock
(C) to remove lower filter housing.
Slide filter housing away from inner fender to remove.
- Remove electrical box (E-box) cover fasteners and remove
cover.
With ignition off, remove ECM relay (arrow) in electronics
box (E-box) at rear of engine compartment, right side.
NOTE-
Relay locations can vary Confirm relay identification by
matching wiring colors and terminal numbers.