secondary air system BMW 528i 1998 E39 User Guide

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130-67
Fuel Injection /
ME 7.2 system overview
The Bosch ME 7.2 system is used on 1999 - 2002 540i mod-
els.
1 4 The ME 7.2 enaine control module (ECM). located on the
l and a combined total of 134 pins.
--__-- 1 I. 9 pin connector
12 3 4 5 2 24 pin connector
0lliC;nii, 3. 52 pin connector
4. 40 pin connector
5. 9 pin connector
The ME 7.2 system has the following functions or capabilities:
Electronic throttle control (EDK) integrates idle and cruise
control functions. ECM carries out all throttle and idle con-
trol functions directly via EDK system.
Leak diagnosis pump
(LDP) control and feedback monitor-
ing for evaporative system leak testing.
Batterylalternator charge logic (idle speed varies with bat-
tery state of charge).
CAN-Bus communications with instrument cluster.
EWS
111 (3.3) "rolling code" ISN interface.
Ignition
knock sensors.
DSC (dynamic stability control) torque reduction.
Monitoring and control of VANOS
(camshaft timing) with
active Hail sensor for camshaft position monitoring.
Integrated altitude sensor.
One touch engine start control
Single speed secondary air injection system.
Long life spark plugs.
IHKA auxiliary (electric) cooling fan control.
All emissions-related ME 7.2 electrical components are mon-
itored for faults. if driveability complaints are encountered or
the malfunction indicator
light (MIL) is illuminated, interrogate
fault memory using a compatible scan tool.
4 Use a break-out box for ME 7.2 system testing and diagnosis
at the control module
(break out box set: BMW special tool
90
88 6 121 300).
Electrically heated (characteristic
map) cooling system
DME Harness Connector thermostat.

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130-75
Fuel Injection
Secondary air injection, overview
The secondary air system pumps ambient air into the exhaust
stream afteracoid engine start to reduce the warm-up time of
the catalytic converters and to reduces HC and CO emis-
sions. The ME
7.2 ECM controls and monitors the secondary
air injection system. The secondary air pump operates at a
starttemperature of between 10°C
(50°F) and 40°C (104°F).
and continues to operate for a maximum of
2 minutes at idle
speed.
The electric air pump draws in ambient air and supplies it to
the
checlc valve. The vacuum vent valve (solenoid) switches
vacuum to open the
checlc valve when activated by the ECM.
Once opened, the checlc
valve allows air to be pumped into
the exhaust stream.
4 The secondary air injection system consists of the following
components:
1. Secondary air pump relay
2. Oxygen sensors
3. Catalytic converters
4. Electric air pump
5. Non-return valve
6. Vacuum vent valve

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Exhaust system1
Exhaust manifold removal procedures are organized accord-
ing to engine code. If necessary, see
100 Engine-General
for engine code and application information.
Exhaust manifolds, removing and installing
(M52 engine)
4 Exhaust manifolds for the M52 engine.
Always use new retaining nuts and gaskets when removing
and installing the exhaust manifolds.
- With exhaust system cold, raise and support car for access
to exhaust system.
WARNING -
Do not work under a lined car unless it is solidly supported on
jack stands designed for that purpose. Never work under a
car that is supported solely by a jack.
- Disconnect secondary air check valve and pipe from exhaust
manifold.
- Unbolt front exhaust pipe@) from exhaust rnanifold(s)
- Remove exhaust support bracket from transmission.
- Loosen and remove nuts from exhaust manifolds and remove
manifolds. Discard nuts and gaskets.
NOTE-
On cars with oxygen sensors mounted in the exhaust mani-
folds, use care when removing manifolds.
To be safe, remove
the sensors from the manifolds before removing manifolds.
- Installation is reverse of removal
Coat exhaust manifold mounting studs with copper paste
before installing new nuts.
Install manifold gaskets with arched side facing manifolds.
Tightening torque
Exhaust manifolds
to cylinder head 20 Nm (15 ft-lb)

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180-6
Exhaust System
Exhaust manifolds, removing and installing
(M52 TU and M54 engines)
I Exhaust manifolds with converters I 4 The exhaust manifolds incorporate the catalytic converters.
Two precatalyst and two post-catalyst oxygen sensors are
mounted in the exhaust manifold assembly.
Under normal conditions, the catalytic converters do not re-
quire replacement unless damaged. Always use new retain-
ing nuts and gaskets when removing and installing the
exhaust manifolds.
I\
1 4 Using engine support equipment (BMW special tools 00 0
200. 00 0 201. 00 0 202.00 0 204.00 0 208 or equivalent).
connect to
lifting eye on front of engine. Rhise engine approx.
/I 1
5 mm (IH in).
With exhaust system cold, raise and support car for access
to exhaust system.
WARNING-
Do not worlc undera liftedcar unless it is solidly supported on
jack stands designed for that purpose. Never worlc under
a
car that is supported solely by a jaclc.
in order to avoid damaging oxygen sensors:
- Detach oxygen sensor harness connectors,
Remove oxygen sensors from exhaust manifolds as de-
scribed later in this group.
Unbolt and remove secondary air
checkvalve and pipe from
right front of cylinder headlexhaust manifold.
Working underneath car, unbolt front exhaust pipes from ex.
haust manifolds.
With engine supported from above, remove right engine
mount
bracket and right engine mount (arrow).
Loosen and remove nuts from exhaust manifolds and remove
manifolds. Discard nuts and gaskets.
CA UTIOG
Take care tliat the front and rear oxygen sensor connectors
are not mixed up.
-

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-- -
Exhaust System
Oxygen sensors (precatalyst), replacing
(M52 TU and M54)
The precatalyst oxygen sensors are installed at the top of the
exhaust manifolds.
WARNING-
Allow components to cool before servicing.
- Using BMW scan tool DlSplus (Diagnostic Information Sys-
tem) or equivalent, read out and clear ECM fault codes.
Working at right side of engine above exhaust manifolds,
remove front or rear oxygen sensor harness connector
(arrows) from bracket, then separate plug.
NOTE-
In photo, secondary air pump has been removed for clarity.
Remove oxygen sensor using special oxygen sensor
removal socket.
Installation is reverse of removal
New sensor threads come coated with anti-seize paste.
If reusing a sensor, apply thin coat of anti-seize paste to
threads only. Do not contaminate tip of sensor with paste
or lubricants of any sort.
Install harness and connector in original location.
Tightening torque
- -.
Oxygen sensor to manifold 50 Nm (37 ft-lb)
Oxygen sensors (post-catalyst), replacing
(M52 TU and M54)
The post-catalyst oxygen sensors are installed at the rear of
the catalytic converters.
WARNING-
Allow components to cool before servicing
- Using BMW scan tool DlSplus or equivalent, read out and
clear ECM fault codes.
- Remove large cover from above fuel raillintake manifold.

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- -
On-Board Diagnostics
Professional diagnostic scan tools available atthe time of this
printing include the BMW factory tools
(DISplus, GTI,
MoDiC) and a small number of aftermarket BMW-specific
tools. See
020 Maintenance.
In addition to the professional line of scan tools, inexpensive
generic OBD
II scan tool software programs and handheld
units are readily available. Though limited, they are
nonetheless powerful diagnostic tools. These tools read live
data streams and freeze frame data as well as a host of other
valuable diagnostic data.
Diagnostic monitors
Diagnostic monitors run tests and checks on specific
emission control systems, components, and functions.
A complete drive cycle is requiredforthe tests to bevalid. See
Drive cycle in this repair group. The diagnostic monitor
signals the
ECM of the loss or impairment of the signal or
component and determines if a signal or sensor is faulty
based on
3 conditions:
* Signal or component shorted to ground
Signal or component shorted to
B+
Signal or component missing (open circuit)
The OBD
II system monitors all emission control systems that
are installed. Emission control systems vary by vehicle model
and year. For example, a vehicle may not be equipped with
secondary air injection, so no secondary air readiness code
would be present.
OBD
II software monitors the following:
Oxygen sensors
Catalysts
Engine misfire
- Fuel tank evaporative control system
Secondary air injection Fuel system
Oxygen sensor monitoring. When driving conditions allow,
response rate and switching time of each oxygen sensor is
monitored. The oxygen sensor heater function is also
monitored. The OBD
II system differentiates between
precataylst and post-catalyst oxygen sensors and reads each
one individually. In order
forthe oxygen sensor to be
effectively monitored, the system must be in closed loop
operation.

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On-Board Diagnostics
Catalyst monitoring. Thisstrategy monitors the outputofthe
precatalyst and post-catalyst oxygen sensors, comparing the
oxygen content going into the catalytic converter to the
oxygen leaving the converter.
The diagnostic executive
lknows that most of the oxygen
should be used up during the oxidation phase. If it detects
higherthan programmed values, afault is set and the MIL
illuminates.
Misfire detection. This strategy monitors crankshaft speed
fluctuations and determines if an enoine misfire occurs bv
monitoring variations in speed between each crankshaft
sensortrigger point. This strategy is so finely tuned that it can
determine the severity of the misfire.
The system determines
if a misfire is occurring, as well as
other pertinent misfire
information such as:
Specific
cylinder(s)
Severity of the misfire event
Emissions relevant or catalyst damaging
Misfire detection is an on-going monitoring process that is
only disabled under certain limited conditions.
Secondary air injection monitoring. Secondary air
injection is used to reduce HC and CO emissions during
engine warm up. Immediately following a cold engine start
(-1 0" to 40°C), fresh air (and therefore oxygen) is pumped
directly into the exhaust
manifold. By injecting additional
oxygen into the exhaust manifold, catalyst warm-up time is
reduced.
Secondary air system components are:
Electric air injection pump
* Electric pump relay
* Non-return valve
Vacuum
I vent valve
- Stainless steel air injection pipes
Vacuum reservoir
The secondary air system is monitored via the use
of the pre-
catalyst oxygen sensors. Once the air pump is active and air
is injected into the system, the signal at the oxygen sensor
reflects a lean condition. If the oxygen sensor signal does not
change, a fault is set and the faulty
bank(s) identified. If after
completing the next cold startafault is again present, the MIL
illuminates.

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On-Board Diagnostics
Readiness codes indicate whether the OED Ii system is
actually ready to monitor the various emission control
systems on the vehicle. The vehicle must complete a drive
cycle to set readiness codes. The code is binary:
0 for ready
1 for not ready
f
4 The parameters which are monitored for readiness are:
llM readiness codes
1. Catalyst efficiency
2. Catalyst heating
3. Fuel tank evaporative control
4. Secondary air injection
5.
NC refrigerant
6. Oxygen sensors
7. Oxygen sensor heaters
8. Exhaust gas recirculation
Readiness codes are set to 1 (not ready) in the following
cases:
~9~~.f~[<+t~t~p:,~;:#j~~{]~y~ ,,... , , 8701Dbd001
The battery or ECM is disconnected.
When
all zeros are displayed, the system has established
DTCs are erased after completion of repairs and a drive
cycle is not completed.
readiness. Readiness codes
can be displayed using BMW
and aftermarket scan tools.
An
OED II scan tool can be used to determine IIM readiness.
Diagnostic trouble codes (DTCs)
SAE standard J2012 mandates a 5-digit diagnostic trouble
code (DTC) standard. Each digit represents a specific value.
Emission related DTCs
start with the letter P for power train.
When the engine service
light (MIL) is illuminated it indicates
that a DTC has been stored.
DTCs are stored as soon as they occur, whether or not the
engine service light illuminates.
DTCs store and display a time stamp.
DTCs record the current fault status: Present, not currently
present, or intermittent.

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OBD-15
On-Board ~iagnosticsl
Engine diagnostic trouble codes: M52 engine (continued)
P-code
PO340
PO412
PO420
PO430
PO440
PO441
PO442
PO443
PO500
PO505
PO600
PO601
PO601
I PO601
~1132
~1133
BMW-FC
65
62
233
234
250 144
-
145
68
214
i I
DTC Definition
Camshalt Position Sensor 'A' Circuit (Bank 1 or Single Sensor)
Secondary Air Injection System Switching Valve A Circuit
Catalyst System Efficiency Below Threshold
(Bank 1)
Catalyst System Efficiency Below Threshold (Bank 2)
Evaporative Emission System
Eva~orative Emission Svstem Incorrect Purge Flow .
Evaporative Emission System Leak Detected (small leak)
Evaporative Emission System Purge Control Valve Circuit
Vehicle Speed Sensor 'A'
204
21 7
100
170
171
188
189
PI161
PI180
PI181
PI184
PI185
PI178
02 Sensor Heater Control Circuit (Bank 2 Sensor 2) I
idle Air Control System
Serial Communication
Link
Internal Control Module Memory Check Sum Error
Internal Control Module Memory
Check Sum Error
Internal Control Module Memory
Check Sum Error
02 Sensor Heater Control Circuit (Bank 1 Sensor
1)
02 Sensor Heater Control Circuit (Bank 2 Sensor 1)
Mass or Volume Air Flow Circuit RangeIPerlormance Problem PI140
I
I I
P1188 1227 I Fuel Control (Bank 1 Sensor 1)
PI145 150 /Solenoid Valve Running Losses Control Circuit Electrical
149
122
223
224
220 221
231
I I
P1189 1228 I Fuel Control (Banlc 2 Sensor 1)
Fuel Trim Adaptation Additive High (Bank 2) (M52: Engine Oil Temperature Sensor Circuit)
02 Sensor Signal Circuit Slow Switching from Rich to Lean
(Bank 1 Sensor 2)
02 Sensor Signal Circuit Slow Switching from Rich to Lean
(Bank 2 Sensor 2)
H02S Sensor Voltage Excursion Electrical (Banlc 1 Sensor 1)
HO2S Sensor Voltage Excursion Electrical (Banlc 2 Sensor 1)
02 Sensor Sianai Circuit Slow Switchina from Rich to Lean (Bank 1 Sensor 1)
02 Sensor Signal Circuit Slow Switching from Rich to Lean (Bank 2 Sensor 1) PI179
I I
PI190 1235 I Pre Catalyst Fuel Trim System (Banlc 1)
PI186 1190 102 Sensor Heater Control Circuit (Banlc 1 Sensor 2)
232
I I
PI191 1236 I Pre
Catalyst Fuel Trim System (Banlc 2)
PI192
. . -- - i Pi193 1226 I Post Catalvst Fuel Trim Svstem (Bank 2)
225
PI397
I I
Post Catalyst Fuel Trim System (Bank 1)
PI421 1246 /Secondarv Air System (Bank 2)
18
Secondary Air System (Bank
1) PI423
Camshaft Position Sensor '0' Circuit (Bank 1)
I 245

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On-Board ~ia~nosticsl
Engine diagnostic trouble codes: M54 engine (continued) I -.
P-code BMW-FC Explanation
PO223 113 ThrottlelPedal Position SensorlSwitch '0' Circuit High
PO261 / Cylinder 1 Injector Circuit Low
PO271 Cylinder 4 Injector Circuit High
PO273 Cylinder 5 Injector Circuit Low
Cylinder 2 Injector Circuit High
Cylinder 3 Injector Circuit
Low
Cylinder 3 Injector Circuit High
Cylinder 4
iniector Circuit Low
PO265
PO267
PO268
PO270
, I
PO277 1 23 1 Cylinder 6 Injector Circuit High
5
22
22
24
I I
PO274
PO301
PO302
PO303
PO304
PO276 1 23 I Cylinder 6 Injector Circuit Low
33
I
I -
I I
PO31 3 1 240 I Misfire Detected with Low Fuel Cylinder 5 Injector Circuit High
238
239
240
241
PO305
I I
Cylinder 1 Misfire Detected
Cylinder 2 Misfire Detected
Cylinder 3 Misfire Detected
Cylinder 4 Misfire Detected
PO313
PO306 1 243 I Cylinder 6 Misfire Detected
242
PO313
PO313
PO31 3
PO327
Cylinder 5 Misfire
Detected
PO31 3 1239 I Misfire Detected with Low Fuel
238
PO332
PO335
PO339 - PO340
Misfire Detected with Low Fuel
241
242
243
57
PO344
PO365
PO369
PO41 3
PO414
PO420
Misfire Detected with Low Fuel
Misfire Detected with Low Fuel
Misfire Detected with Low Fuel
Knock Sensor 1 Circuit Low
(Banlc 1 or Sinale Sensor)
59
83
83
65
-
Knoclc Sensor 2 Circuit Low (Banlc 2)
Crankshaft Position Sensor
'A' Circuit
Crankshaft Position Sensor
'A' Circuit Intermittent
Camshaft Position Sensor 'A' Circuit (Bank 1 or Single Sensor)
65
18
18
62
62
233 Camshaft Position Sensor
'A' Circuit Intermittent (Bank 1
or Single Sensor)
Camshaft Position Sensor
'B' Circuit (Banlc 1)
Camshaft Position Sensor 'B' Circuit Intermittent (Bank 1)
Secondary Air Injection System Switching Valve A Circuit Open
Secondary Air
Injection System Switching Valve A Circuit Shorted
Catalyst System Efficiency Below Threshold (Bank 1)