1999 BMW 528i Idle

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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 Injection
ECM relay, testing
The engine control module (ECM) relay is energized via the
ECM and supplies battery positive
(B+) power to many of the
engine
management components and subsystems. If this re-
lay is faulty, the engine will not start.
CAUTIOI\C
Relay positions can vary. Be sure to confirm relay position by
identifying the wiring
in the socket using the wiring diagrams
in ELE Electrical Wiring Diagrams.
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
(5.2.1 only)
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 unloclc from bulk head and
remove duct.
0 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.

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130-51
Fuel Injection
Oxygen sensors, checking
The oxygen sensor provides an input voltage signal [0.2 vdc
(lean) to 0.8 vdc (rich)] to the
ECM based on the oxygen con-
tent in the exhaust gas. To generate voltage, the sensor tem-
perature must exceed 575"
F (300" C). Therefore the sensor
is electrically heated.
NO JE -
The test given below is not a conclusive test of oxygen sen-
sor efficiency and does not test how the oxygen sensor re-
acts to changing conditions. Pin numbers and wire colors
can vary Always check the wiring diagrams to confirm wire
color and pin assignment.
0 The oxygen sensorconnectorplugs are locatednext to the
catalytic converters.
With connector attached to sensor, connect digital voltmeter
between
A and B wires in connector.
WARNING -
Exhaust manifolds andpipes can be hot enough to cause se-
rious burns. Wear suitable heavy gloves and other appropri-
ate protection.
NOJE-
Connector style may vary depending on system application.
Consult wiring diagram for system-specific wiring. See
ELE
Electrical Wiring Diagrams.
Start engine.
A fluctuating voltage signal should show on the
meter.
If voltage is incorrect, turn engine off and check pre-
heater circuit as described below.
NOJE-
To check sensor response to lean and rich mixtures, create
an air leak.
Oxygen sensor
voltage at idle
- Connect digital voltmeterbetween sensor heaterwires (white
wires,
C and D). Start engine and check for battery voltage.
If voltage is not present, check oxygen sensor heater fuses.
0.2 to 0.8 vdc fluctuating
NOJE-
The oxygen sensor heater is powered via fusedpositive (+)
battery voltage and a switchedground from the ECM. See
ELE Electrical Wiring Diagrams for specific circuit informa-
tion.
- The ground side of the oxygen sensor heater circuit is pulsed
on and off by the
DME control module.

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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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Fuel Injection
- If voltage is present as described above, check wiring be-
tween ECM and valve. If no wiring faults are found, check
ECM signal to valve.
- When replacing idle speed control valve, clean and inspect
all sealing areas.
. Inspect sealing ring in throttle body and replace if neces-
sary.
Throttle position sensor (TPS),
testing and replacing
The throttle position sensor (arrow) is mounted on the side
of the primary throttle housing and is directly connected to
the throttle valve shaft. The ECM sends a voltage signal to
the potentiometer-type sensor and monitors the voltage that
comes back. Resistance decreases (voltage increases) as
the throttle opens.
NOTE-
Do not confuse the TPS on the primary throttle housing with
the throttle switch on the
ASC secondary throttle housing.
4 Check throttle position sensor function by disconnecting har-
ness connector and checking across terminals. If any faults
are found, replace throttle position sensor.
Engine coolant temperature (ECT) sensor,
testing and replacing
Throttle position sensor (M62 engine)
The ECT sensor is located on the front of the engine in the
coolanVthermostat flange.The ECTsensor is a dual tempera-
ture sensor. One circuit provides coolant temperature infor-
mation 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
Test
value
5 vdc (approx.)
4.0 kR(approx.)
Continuously variable
from
1.0 to 4.0 kR
without interruption
Test
conditions
Harness connector
disconnected, ignition on
Harness connector
disconnected,
ignition on
Throttle plate rotated from idle to
full throttle position Test Terminal
Term.
1 at
harness
connector and ground
Term.
1 and term. 3 at
sensor
Term.
1 and term. 2 at
sensor

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Fuel Injection
Intake air temperature
([AT) sensor,
testing and replacing
Disconnect harness connector from intake air temperature
sensor
(A) at air filter housing.
Turn ignition on. Using a digital voltmeter, check for
5 volts
between supply voltage wire in connector and ground.
If volt-
age is not present, test ECM
inputs/outputs as described lat-
er.
With harness connector disconnected, test resistance across
sensor terminals. If any faults are found, replace IAT sensor.
IAT test resistance
0 lV *lac (50" i-2°F) 7-1 1.6 k.0.
020' kl°C (68' 322°F) 2.1-2.9 it.0.
080" ?lac (176" i-2°F) 0.27-0.40 itn
Auxiliary throttle valve (ADS)
(M62 and M62 TU engine), replacing
ADS components 540i models with ASC and DSC are fitted with a motor-driv-
en auxiliary throttle valve and housing ahead of the standard Throttle position switch throttle housing. The ADS throttle valve controls engine throt-
tle intervention based on signals from the DME control mod-
ule if road conditions, such as slipping driven wheel, warrant
reduced engine power.
ADS throttle housing
Bowden cable NOTE-
Before replacing the ADS throttle housing, read DME fault
ADS lhroltle actualor codes.
- ADS throttle housing replacement:
Switch off ignition and disconnect electrical connector on
ADS throttle body.
Remove hose from idle control valve.
Loosen hose clamps and remove throttle housing air in-
take boot.
Disconnect cable from ADS throttle body.
- Unscrew 3 bolts and remove ADS throttle body.
Installation is reverse of removal.
- Adjust cable so that no free play is present.

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Fuel Injection Evaporative fuel system pressure leak
diagnosis, overview
(M5.2.1 only)
1998 540i models are equipped with an evaporative fuel sys-
tem pressure leak diagnosis system. The main component of
this system is the leak diagnosis pump (LDP). The function of
the LDP is to pressurize the fuel tank and the evaporative
emission system for the purpose of detecting
leaks. This sys-
tem is capable of detecting a leak as small as 0.5 mm.
The LDP, located in the left rear wheel housing, is a unitized
component that contains the following:
Vacuum chamber. Pneumatic pump chamber.
DME activated vacuum solenoid
Reed switch (provides switched voltage
feedback signal to
ECM).
The vacuum supply line is in the wiring harness from the en-
gine compartment and runs down the driver's side of the vehi-
cle.
The canister vent valve is integrated into the LDP, which is
electrically controlled by the ECM. The canister vent valve is
opened to provide fresh air entry into the fuel system only dur-
ing purge operation.
- Purge operation characteristics:
Off idle through full throttle: purge valve opened by pulse
width modulated (PWM) control of the ECM. PWM duty cy-
cle varies by engine operating conditions
(e.g. warm idle,
purge valve opened slightly; cold
idleldecel with engine
temp
< 67" C, purge valve always closed).

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130-59
Fuel Injection
:-- -i. Evaporative emissions
1.
control diagram (M5.2.1)
i 1
i I @ 1. ECM r.=.:-:, 2. Purge valve
3. Leak detection pump (LDP)
4. Liquid vapor separator
5. Purge canister
6. Filter
Bosch M5.2 ECM pin assignments
(M62 up to 911997)
Tabled. Bosch M5.2 ECM pin assignments
I' 1- 1. . . -
4 1 output / Cyl. 4 fuel injection valve I Cyl. 4 fuel injection valve (cycled ground)
Pin
1
2
3
i I
I
7 / output I Cyl. 6 fuel injection valve I Cyl. 6 fuel injection valve (cycled ground)
Type
output
output
output
I I ,
8 1 output I Malfunction indicator light (MIL) (USA only) I lliumlnated for exhaust gas related diagnostic trouble code
5
Component/function
Oxygen sensor heater signal
Idle speed control -closing winding
Cvl. 1 fuel iniection valve Note
DME heated oxygen sensor
1 splice
idle speed control valve (cycled ground)
Cvl. 1 fuel iniection valve lcvcled around)
6 1 ground I Fuel injection valve ground 1 Ground
output
9
Not
used
Not used
11
12
13
Cyl. 5 fuel injection valve
10 1 input I Electronic immobilizer (EWS) / Electronic immobilizer (EWS) control unit
input
Heated oxygen sensor signal Cyl.
5 fuel injection
valve (cycled ground)
output
input
input
16
Start signal Starter relay
NC compressor signal
Terminal
50 signal
Knock sensor signal
17 1 ground I Hot film mass air flow (MAF) sensor ground I Hot film mass air flow (MAF) sensor ground
output Heating and
A/C control module
Ignition switch
Knock sensor
Intake air temperature intake air temperature sensor (voltage value)