Honda Bmw 5 Service Manual

							
120-3 
Ignition System 
Warnings and cautions 
The ignition system  produces dangerous  high voltage. In ad- 
dition  the sensitive electronic components  can be damaged 
if 
proper  precautions are  not adhered  to. 
WARNING- 
* Do  not touch  or disconnect  any cables from the coils while 
the  engine  is running  or being 
cranked by  the  starter. 
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. 
- Connect and disconnect tlie DME  system wiring and 
test  equipment leads  only when the ignition is 
OFF: 
Before operating  the starter without starting  the engine 
(for  example when 
making a compression  test) always 
disable  the ignition. 
CA 
U TIOW- 
Do  not attempt  to disable  the ignition  by removing  the coils 
from  the spark plugs. 
Connect  or disconnect  ignition system wires, multiple 
wire  connectors,  and ignition test equipment  leads only 
while  the ignition is 
off Switch multimeter functions  or 
measurement ranges  only  with the test  probes  discon- 
nected. 
* Do not disconnect  the battery while the engine is run- 
ning. 
A  high impedance digital  multimeter should be used  for 
all  voltage  and resistance tests.  An LED test light 
should  be used  in place  of an incandescent-type test 
lamp. 
In  general,  make test connections only as specified  by 
BMW as described  in this  manual,  or as described  by 
the  instrument  manufacturer. 
Engine management 
BMW €39 engines use  an advanced  engine management 
system known as  Digital Motor Electronics  (DME). DME in- 
corporates on-board  diagnostics, fuel injection,  ignition and 
other  engine control functions.  DME variants are  listed in 
Table  a. Engine  management  systems. 
Second  generation On-Board Diagnostics 
(OED II) is incor- 
porated  into the engine  management  systems used on the 
cars  covered  by this manual. Use  a BMW-specific electronic 
scan  tool, or a Generic 
OED II scan  tool to access Diagnos- 
tic Trouble  Codes (DTCs).  DTCs can help  pinpoint  ignition 
ine  management problems.   
						

							
I lgnition System 
Additional information about DTCs and engine management 
system electronic system  diagnosis is provided in 
OBD On- 
Board Diagnostics. 
Table  a. Engine  management  systems 
Year 
l~ngine I Engine type IDME svstem I - I - . . I 
Ignition system 
1997-1 998 
1997 
1998 
1999-2002 
4 All  engines  use a distributorless  ignition system with individ- 
ual  ignition  coils for  each cylinder.  There is no distributor  cap 
or ignition  rotor. 
4 Each coil is controlled  and monitored  by the  Engine Control 
Module  (ECM) on a cylinder-by-cylinder  basis. 
1999-2000 
1~52 TU 16-cylinder l~iemens MS 
42.0 
M62 
M62 
M62TU 
Siemens  MS 41 .I M52 6-cylinder 
V-8 
V-8  V-8  Bosch 
M 5.2 
Bosch M 5.2.1 
Bosch  ME 7.2   
						

							
Lnition switch 
4 The positive (+) power supply  to the ignition coils  comes to 
the ignition  switch via an unloader  relay. When  the ignition 
switch  is turned on, the  relay closes,  to provide  voltage to the 
ignition  coils. The coils are  then actuated  at the  negative  side 
by  the engine control module. 
NOTE- 
Schematic diagrams shown are  for illustrative purposes  only. 
See  ELE  Electrical  Wiring Diagrams  for engine manage- 
ment specific wiring information. 
WARNING-  Do  not  touch  or disconnect  any cables  from the coils  while 
the  engine  is running  or being  cranked  by the starter: 
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. 
* Connect  and disconnect the DME system wiring  and 
test equipment leads only  when the ignition is 
OFF 
Before operating  the starter  without  starting  the engine 
(for  example  when 
making a compression  test), always 
disable  the ignition. 
4 Knock  sensors  (arrows)  monitor the  combustion  chamber for 
engine-damaging  knock. Six-cylinder models (shown)  use 
two  sensors with each  sensor monitoring three  cylinders. 
V- 
8 models use four sensors, each monitoring  two cylinders. If 
engine 
knock is detected, the ignition point is retarded  by the 
ECM. 
I Ignition  advance Ignition timing  is electronically mapped and  not adjustable. 
The  ECM  uses engine load,  engine speed, coolant  tempera- 
ture,  knock detection, and intake  air temperature as the basic 
inputs  for timing  control. 
A three dimensional  map similar  to 
the  one  shown  is digitally  stored in the  ECM. 
- The initial ignition point is  determined by the crankshaft 
speed sensor during cranking.  Once the engine is  running. 
timing  is continually adjusted  based on operating  conditions.   
						

							
120-6 
lgnition System 
lgnition system, troubleshooting 
Troubleshooting ignition  system faults should begin with an 
interrogation  of the  On-Board Diagnostics (OBD 
II) system. 
The OBD 
II system detects ignition system misfire  and other 
related faults. When  faults are detected, the  OBD 
II system 
stores a Diagnostic Trouble  Code (DTC)  in the  Engine  Con- 
trol Module (ECM) along with other pertinent  fault information. 
4 In addition, the Malfunction Indicator Light (MIL) will  come on 
if  an emissions related  fault is detected.  Additional OBD 
II in- 
formation,  including a DTC  lookup table, can be found in 
OED On-Board  Diagnostics. 
NOTE- 
BMWmodels covered in this  manual  were equipped  with one 
of  three versions  of 
MIL warning lights (as shown). 
Misfire detection 
Engine m~sfire in one or more  cylinders, may be caused  by a 
var~ety of malfunctions in various subsystems. The OBD II 
system ~ncorporated into the engine management systems is 
des~gned to  detect and warn  of misfire  faults during englne 
operat~on. See OED On Board  Diagnostics. 
WARNING - 
lgnition  misfires  can cause  high hydrocarbon  exhaust emis- 
sions  andcatalytic  converter damage. For this  reason,  if a  se- 
vere  misfire  is detected,  the fuel injector 
will be turned off  to 
the  specific cylinder  and the 
MIL will be illuminated. A misfire 
may  also produce  an overheated  catalytic converter, which 
can  be a fire hazard. 
Oscilloscope  diagnostic diagrams 
One way to diagnose a faulty coil is  to use  an oscilloscope  to 
analyze spark quality  with the engine running. 
See  Table  b. lgnition  secondary voltage diagnostics  for 
list  of common ignition 
coil voltage faults and related  causes.   
						

							
120-7 
Ignition System 
Spark plug electrode  gap /Too small /TOO big 
Table 
b. Ignition  secondary voltage diagnostics 
Secondary 
voltage low 
Fuel air  mixture 
I I Too lean 
Secondary 
voltage high 
Spark plug electrode 
Worniburnt 
4 The  illustration shows normal scope trace of spark  at idle. 
1. Start  of ignition  voltage peak 
2 Level of ignition  voltage 
3. Level of combustion  voltage 
4. Period of combustion 
5. Combustion curve characteristics 
6. Start  of decay process 
7. Termination  oscillations 
Spark plug  electrode 
temperature 
Engine  compression 
Spark plug wires 
4 Short  combustion  period (indicates  large spark plug  gap). 
Too 
high 
Too 
low 
I 9, 10 I to I!, r) i 21 10 il bW,rn?7G 
Too low 
Too high 
Faulty 
4 Ignition spark  at idle  speed. 
A - Normal  ignition voltage peak (spark plug is good). 
B - Low  voltage peak is an  indication  of a closed plug  gap. 
C 
- High voltage peak indicates  an open  plug gap. 
< Long combustion  period (indicates  small spark plug gap). 
~i,+i!,~,i~tiii~iit~~,t1!lc,,l~~4~l~,~,l,~+~{+,,l 1W W Sl ,@ 10 :o 9 20 21 10 0   
						

							
I lgnition System 
4 Normal combustion  period at idle. 
4 Normal  oscilloscope  pattern for ignition  system  at idle. 
15. 15 
4 lgnition  voltage  peaks  at idle. 
1. Normal ignition  peaks. 
2. Downward peak (arrow) is shortened  (ignition  coil is 
defective). 
3. Downward  peak (arrow)  is missing completely  (ignition 
coil  is defective). 
4 Defective  ignition coil. 
1. Short spark  period. 
2. The spark voltage  line (arrow)  is very slight 
< Defective  ignition coil. 
1. Normal combustion  period. 
2. Absence of spark voltage line  (arrow). 
(r+~+~+~(.~i+~/.~~itlt~~(tit~lii~~jt~~~i~ittiii~l IW 10 ED 10 (0 ID U 10 11 70 0 sa,ma, 
2 . 15 - . 
5 - - - 0 
30 
. 
. 
20 . 
I0 - - 
0 
iiiCi;kiW*huiMwiritil~tiii 110 10 00 ro w M A, 30 2 *:,:mu   
						

							
< Ignition voltage peaks in response  to sudden  acceleration 
load: 
1. Normal ignition  pattern. Beginning  of dying out  pattern 
is  not  much higher than ignition  voltage peak. 
2. Beginning  of dying out pattern  considerably  higher  than 
ignition  voltage peak.  Fault  in injection  system: 
Lean  fuel mixture 
Defective  fuel injector 
Low compression  in cylinder 
-, :I 1- i : .... 1 ...,,,,. J ,,,.! ,.,. { .,., i .,,, 8 ,.,.$,.,! ,:,, ., xt * , *, ,, >* m2>2n,,,, 
Ignition firing  order 
Normal secondary  voltage patterns 
(4-cylinder  pattern shown). 
4 Each ignition coil is mounted  above the corresponding spark 
plug. 
- Number one  cylinder is located  at the  front  on 6-cylinder 
models. 
Number  one cylinder is located  at the right  (passenger side) 
front on 
V-8 models.  Cylinder firing  order is shown. 
Firing  order 
M52 - M52 TU - M54 6-cylinder 1-5-3-6-2-4 
M62 - M62 TU V-8 1-5-4-8-6-3-7-2   
						

							
.- 
ignition System 
Disabling ignition system 
The ignition system operates in a lethal voltage range and 
should be disabled  any time  engine  service  or repair  work is 
being  done that  requires the ignition to be switched on. 
The engine management  system can be disabled  by remov- 
ing the DME main relay. The  relay is located  in the electronics 
box (E-box)  in the left rear  of the engine 
compartment, be. 
neath the interior microfilter housing. 
CAUTION- Relay locations  may 
vary. Use care  when  identifying  relays. 
See 
610 Electrical  Component  Locations. 
Checking for spark 
CAUTION- 
If 
a spark  test is done incorrecth damage  to the  Engine Con- 
trol  Module 
(ECM) or the  ignition coils may  result. 
NOTE- 
Spark plug replacement  is covered  in 020 Maintenance. 
Check~ng for spark  is d~fflcult on englnes wlth d~str~butorless 
ignition systems. 
Try removing the spark plugs and inspecting for differences  between  them. 
A poor-firing plug  may be wet  with fuel and/or ~. - ~ 
black  and sooty,  but not always.  If a coil is not operating, the 
engine management system will electrically disable the fuel 
injector  to that cylinder. The key is to  look for differences be- 
tween cylinders. 
Ignition  coil assembly,  testing and 
replacing 
C4 UTION- 
Use  a digital multimeter for  the  following  tests. I 
- Remove plastic engine  cover from top of valve  cover  by pry- 
ing  off bolt covers and removing  cover mounting  bolts. 
- Raise car  slowly while constantly checking position  of jack 
and  car. 
- Disconnect harness connector from  coil. Connect multimeter 
between terminal  15 
(+) in connector and ground. 
4 Terminal identification are typically molded into connector. In 
photo, terminals are  from left to right:  1, 
4a, 15.   
						

							
Ignition System 
- Turn ignition on and  check for battery voltage, 
If  battery voltage is not present, 
checlt wire between  termi- 
nal 
15 and the unloader  relay. See ELE Electrical Wiring 
Diagrams. 
- Turn  ignition  off. 
Remove  coil and inspect coil housing  for hairline 
cracks or 
leaking casting material. Replace  any 
cracked or leaking coil. 
NOTE- 
A leaky coil may  indicate a faulty Engine Control Module 
(ECM).  Check ECM before installing a  new coil. 
CAUTION- 
Note  location  of coilground  straps before coil removal;  rein- 
stall  in the  same  location. 
Use a multimeter  to test: 
Coil primary resistance at coil terminals. 
Sparlt plug connector  resistance. 
* Compare results  to specification in  Table c. lgnition  coil 
resistance. 
Table  c. Ignition  coil resistance 
Coil  secondary 
resistance 
Spark plug  connector: 
Bosch 1 .O I( ohm t 20% 
1.8 ir ohm t 20% 
Component 
Co~l prlmary 
resistance 
- Replace ignition coil or sparlt plug connector  if resistance 
readings do  not meet specifications. 
4 Remove ignition coil to  be tested. 
Install 
BMW special tool 12 7 030 (A) on coil  to be  tested. 
Connect ground jumper between  coil  mounting point 
(B) 
and engine  ground point (C). 
Clip scope high pick-up lead (D) around ignition lead. 
Start  engine. 
Compare scope pattern with diagrams in  Oscilloscope 
di- 
agnostic diagrams. 
NOTE- 
When replacing ignition  coils, ensure  that the  replacements 
Terminal 
1 (-) and 15 (+) 
are 
from the  same manufacturer  with the same partlcode 
numbers. If individual  coils with the  correct specifications  are 
not  available.  all coils  should  be 
re~laced. 
Resistance 
0.8 ohms   
						

							
120-1 2 
ignition System 
Crankshaftspeedsensor 
Crankshaft speed sensor, replacing (M52, M52 TU and 
M54 engines) 
4 Crankshaft speed sensor  for 6-cylinder engine is mounted in 
the left rear side  of the cylinder  block below the starter  (ar- 
row).  The sensor reads a toothed pulse wheel mounted to 
the end  of the crankshaft. 
- if the  Engine Control Module (ECM)  does not receive a signal 
from  the crankshaft speed  sensor during cranking,  the en- 
gine will not start. 
- If the  OBD II svstem misfire detection ~rotocol detects a  cat- -  - ~~ 
alysr oarnagin; faLlt oJe to a ma I-nclion in crandshafi speeo 
sensor  components.  Ine Check  Engine 
lignr (Malfuncrion  In- 
dicator Light  or MIL) will  be illuminated. 
NOTE- 
If the  crankshaft  speed sensor  pulse wheel  is damaged, the 
engine  will have  to be  disassembled down  to the  crankshaft 
to 
reolace the  wheel. 
- Make  certain ignition has been turned  off. 
- Raise car and support  in a safe manner. 
WARNING - 
Make sure  the car  is stable  and well supported  at all times. 
Use  a professional  automotive lift orjacltstands  designed for 
the  ouroose. 
A floor iaclc is not  adequate support. 
- Remove  under engine splash guard 
4 Working underneath starter: 
Cut  off wire tie  securing crankshaft speed  sensor harness 
connector  (arrow) to sensor. 
* Disconnect harness connector. 
4 Remove sensor  mounting fastener (arrow) and remove  sen- 
sor  from  cylinder  block. 
- Installation  is reverse  of removal, noting  the following: 
Use a new O-ring  when installing  sensor. 
Be sure wiring  is routed in  same orientation. 
Secure sensor using new  wire ties. 
Use  scan  tool to  read  out and clear ECM  fault memory.