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Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
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Audi A8 1994 ➤

Motronic injection and ignition system (6-cylinder)

Engine ID

AQD APR

Edition 02.1999

Service

Service Department. Technical Information

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Summary of Contents for A8 1994

Page 1: ...ss authorised by AUDI AG AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document Copyright by AUDI AG Audi A8 1994 Motronic injection and ign...

Page 2: ...8 1994 Motronic injection and ignition system 6 cylinder Repair Group 01 Self diagnosis 24 Mixture preparation Injection 28 Ignition system Technical information should always be available to the fore...

Page 3: ...uel rail with injectors 28 1 7 Removing and installing parts of intake manifold change over 29 1 8 Wiring and component check with test box V A G 1598 31 30 1 9 Renewing engine control unit J220 31 1...

Page 4: ...or electronic throttle in dash panel insert 80 7 Checking accelerator position senders G79 and G185 81 7 1 Checking accelerator position senders G79 and G185 81 7 2 Checking brake light switch F and b...

Page 5: ...diagnostic testing and information system VAS 5051 and the fault reader V A G 1551 can register Page 1 List of selectable functions The fault memory is equipped with a non volatile memory and therefor...

Page 6: ...th diagnosis cable V A G 1551 3 Warning When performing test drives and checks the vehicle diagnostic testing and information system VAS 5051 as well as the fault reader V A G 1551 may be secured only...

Page 7: ...e run through the fault finding procedure as de scribed in the Fault Finding Programme for diagnosis wiring Rapid data transfer HELP Control unit does not answer Current Flow Diagrams Electrical Fault...

Page 8: ...engine does not start turn over the engine with the starter motor for at least 5 seconds then leave the ignition switched on Switch on printer with the Print button Warning lamp in button lights up I...

Page 9: ...ended when the following appears on the display V A G SELF DIAGNOSIS HELP 1 Rapid data transfer 2 Flash code output Erase all fault memories and then carry out a road test Interrogate the fault memor...

Page 10: ...der G42 Signal too small Test intake air temperature sender P0113 16497 Intake air temp sender G42 Signal too large Page 49 P0116 16500 Coolant temp sender G62 Implausible signal Test coolant temperat...

Page 11: ...ion SAE V A G P0571 16955 Brake light switch F Implausible signal Test brake light switch Page 83 P0601 16985 Control unit defective Renew engine control unit P0604 16988 Control unit defective Page 3...

Page 12: ...daption add System too lean Take car for test drive fuel in oil P1137 17545 Bank 1 Mixture adaption add System too rich Check fuel system pressure Page 34 P1138 17546 Bank 2 Mixture adaption add Syste...

Page 13: ...ositive Fault code Readout on fault reader display Fault rectification SAE V A G P1225 17633 Injector Cyl 1 N30 Short to Earth Test injectors P1226 17634 Injector Cyl 2 N31 Short to Earth Page 36 P122...

Page 14: ...ng 2 Control limit surpassed 1 Test throttle valve control part Page 31 P1336 17744 Engine torque monitoring Control limit surpassed Renew engine control unit Page 31 1 If this fault occurs the engine...

Page 15: ...ion and or wiring from engine con trol unit to ignition out put stage Page 99 P1394 17802 Ignition output 2 Electrical fault in current circuit P1395 17803 Ignition output 3 Electrical fault in curren...

Page 16: ...99 Open circuit P1434 17842 Relay for sec ondary air pump J299 Short to Posi tive Test secondary air pump relay Page 70 P1435 17843 Relay for sec ondary air pump J299 Short to Earth P1436 17844 Relay...

Page 17: ...Readout on fault reader display Fault rectification SAE V A G P1539 17947 Clutch pedal switch F36 Implausible signal Test clutch pedal switch Page 85 P1542 17950 Angle sender for throt val drive G187...

Page 18: ...Voltage supply Kl 30 Voltage too low Page 102 P1603 18011 Control unit defective Renew engine control unit Page 31 P1604 18012 Control unit defective 1 P1612 18020 Engine control unit Wrongly coded Ch...

Page 19: ...y listening or by touching If the final control diagnosis is to be repeated the engine must be started The engine control unit needs to detect an engine speed of more than 300 rpm The electric fuel pu...

Page 20: ...lter N80 Page 72 Activating secondary air inlet valve only on vehicles with secondary air system Press key Indicated on display Final control diagnosis Secondary air inlet valve N112 The solenoid valv...

Page 21: ...ement If the valves are not actuated do not click Mechanics Repair group 15 Testing camshaft timing control Testing solenoid valves for camshaft adjust ment Testing camshaft timing control Testing sol...

Page 22: ...entry by pressing Q Indicated on display Basic setting Enter display group number XXX Select the required display group number from the Display Group Overview in the Read measured value block section...

Page 23: ...l the display zones match the specifications press the key Indicated on display Rapid data transfer HELP Select function XX Press keys 0 and 6 for the function End output and confirm entry with the Q...

Page 24: ...unit identification as in this example 3B0907551 2 8l V6 5V G D Coding 05753 WSC 06388 Press key Indicated on display Rapid data transfer HELP Select function XX Press keys 0 and 6 for the function E...

Page 25: ...or fault reader V A G 1551 and select engine electronics control unit by entering address word 01 Page 2 When doing this the engine must be idling Indicated on display Rapid data transfer HELP Select...

Page 26: ...ntify and record faults The fault memory should therefore be interrogated and if necessary erased after completing the tests and any repair work that may be re quired Always switch off the ignition be...

Page 27: ...approx 2 2 bar Engine warm approx 3 0 bar Injectors Spray pattern Two hole injector Injection quantity 30 sec 90 125 ml Resistance room temperature 1 13 5 15 5 1 When the engine is at operating tempe...

Page 28: ...ronics box in plenum chamber Engine control unit J220 Secondary air pump relay J299 only on vehicles with secondary air system 2 Coolant temperature sender G62 On coolant pipe behind cylinder head Ban...

Page 29: ...ument Copyright by AUDI AG 6 Secondary air inlet valve N112 Only on vehicles with secondary air system 7 Throttle valve control part J338 8 Intake air temperature sender G42 9 Intake manifold change o...

Page 30: ...document Copyright by AUDI AG 12 Fuel pressure regulator 13 Hall sender G40 Cylinder bank 2 14 Engine speed sender G28 In gearbox housing above starter ring gear 15 Knock sensor 2 G66 16 Camshaft adj...

Page 31: ...spect to the correctness of information in this document Copyright by AUDI AG 19 Knock sensor 1 G61 20 Hall sender G163 Cylinder bank 1 21 Camshaft adjustment valve 1 N205 22 Air mass meter G70 23 Sec...

Page 32: ...information in this document Copyright by AUDI AG 1 6 Dismantling and assembling fuel rail with injectors 1 Fuel rail 2 To T piece 3 Retaining clip 4 O ring Renew 5 Fuel pressure regulator 6 O ring Re...

Page 33: ...on in this document Copyright by AUDI AG 1 7 Removing and installing parts of intake manifold change over 1 Vacuum unit 2 Spring 3 Change over barrel 4 Intake manifold 5 Non return valve Installation...

Page 34: ...if damaged 14 Seal For change over barrel 15 6 Nm 1 8 Wiring and component check with test box V A G 1598 31 Notes Test box V A G 1598 31 is designed so that it can be connected to the wiring harness...

Page 35: ...onnectors on engine control unit and unplug connectors Connect test box V A G 1598 31 to wiring harness connector Also connect the earth clamp on the test box to earth The instructions for performing...

Page 36: ...he engine control unit Page 32 Interrogate fault memory and erase if necessary Page 4 Activating cruise control system Connect vehicle diagnostic testing and information system VAS 5051 or fault reade...

Page 37: ...the engine then start up again Take the vehicle for a test drive and interrogate the fault memory again to make sure it is clear Run the engine at idling speed Warning The electric radiator fan should...

Page 38: ...ntry with the Q key If the readout does not match the specification interrogate fault memory again If the idling speed is too high or too low and there are no faults recorded in the fault memory carry...

Page 39: ...art the engine and run at idling speed Measure fuel pressure Specification approx 3 8 4 2 bar If fuel pressure does not match specification fit a new fuel pressure regulator for test purposes and repe...

Page 40: ...on between pressure gauge and fuel supply pipe leaking Supply pipe leaking at fuel tank Return valve in fuel pump leaking 6 cylinder Engine Mechanics Repair Group 20 Removing and installing fuel pump...

Page 41: ...e engine is at operating temperature the electrical resistance of the injectors will be about 4 6 higher If the specification is not obtained Renew injector If specification is met Test voltage supply...

Page 42: ...the wiring from socket 1 to fuel pump relay via fuse for injectors If necessary rectify open circuit Current flow diagrams Electrical fault finding and Fitting locations binder Checking wiring connec...

Page 43: ...circuit and short to positive or earth in the following wiring connections Cylinder 2 pin connector on wiring harness socket Test box V A G 1598 31 socket 1 2 96 2 2 112 3 2 88 4 2 97 5 2 113 6 2 89 R...

Page 44: ...on quantity tester V A G 1602 Connect test box V A G 1598 31 to wiring harness for engine control unit Do not connect to the engine control unit itself Page 30 Bridge contacts 1 and 65 on the test box...

Page 45: ...have been activated place the three measuring glasses on a level surface Specification for each injector 90 125 ml If the measured value for one or more of the injectors is outside the tolerance range...

Page 46: ...engine is turning over In other words the relay is only earthed via the engine control unit when the engine control unit is receiving engine speed impulses Test conditions Battery voltage OK Functiona...

Page 47: ...the engine control unit itself Page 30 Connect sockets 65 and 2 of test box to each other using auxiliary cable from V A G 1594 Specification the fuel pump relay relay position 4 should pick up If th...

Page 48: ...nd short to positive or earth in the following wiring connections Micro central electrics in pas senger s footwell right re lay position 4 Contact Test box V A G 1598 31 Socket 16 65 Rectify any open...

Page 49: ...t Air conditioner switched off Fuse for air mass meter OK Current flow diagrams Electrical fault finding and Fitting locations binder Testing operation Connect vehicle diagnostic testing and informati...

Page 50: ...th the Q key Switch off the ignition Reading Display Group 2 Display zone 3 Possible cause of fault Fault remedy Less than 1 0 ms Lower values can only occur when vehicle is on overrun More than 4 0 m...

Page 51: ...tage Test for open circuit or short to earth in wiring between fuel pump relay and contact 3 on connector via fuse Repair if necessary Current flow diagrams Electrical fault finding and Fitting locati...

Page 52: ...Specification infinity open circuit If the wiring and the power supply are OK fit a new air mass meter G70 1 16 Checking intake air system for leaks unmetered air Checking with engine leak detector sp...

Page 53: ...nd output and confirm entry with the Q key Check sprayed areas of intake system for leaks and rectify if necessary 1 17 Testing intake air temperature sender G42 Fitting location of sender and connect...

Page 54: ...120 C Note If the display shows a temperature that differs excessively from surround ing temperature test wiring Page 50 Testing wiring Switch off ignition Connect test box V A G 1598 31 to wiring ha...

Page 55: ...XX Press keys 0 and 8 for the function Read measured value block and confirm entry with Q key Indicated on display Read measured value block Enter display group number XXX Press keys 0 0 and 4 to sele...

Page 56: ...new coolant temperature sender G62 2 Testing lambda control 2 1 Testing lambda control 2 2 Operation of lambda control The lambda probes compare the oxygen content in the air with the residual oxygen...

Page 57: ...ue block mode it is possible to switch back and forth between function 04 Basic setting and function 08 Read measured value block by pressing keys 4 and 8 on fault reader V A G 1551 When exiting the B...

Page 58: ...da control 0 inactive 1 active X Lambda probe condition 0 inactive 1 active X Status of lambda probe heating 0 inactive 1 active Testing lambda probe learned values and lambda control Connect vehicle...

Page 59: ...match specification Page 56 If readout does not match specification Page 56 If readout does not match specification Page 56 Press key C Press keys 0 3 and 3 to select Display Group 33 and confirm entr...

Page 60: ...ution Carry out oil change or drive car at moderate to high speeds on out of town roads High oil consumption Air mass meter defective Test air mass meter Page 45 Solenoid valve for activated charcoal...

Page 61: ...eating circuit is monitored by the self diagnosis system Interrogate fault memory Page 4 Connect vehicle diagnostic testing and information system VAS 5051 or fault reader V A G 1551 and select engine...

Page 62: ...Page 58 Testing voltage supply for lambda probe heating Test fuse for lambda probe heating Current flow diagrams Electrical fault finding and Fitting locations binder Connect hand held multimeter vol...

Page 63: ...ification approx battery voltage fluctuating Note At certain points in the operating range the engine control unit continuously switches the earth connection to the lambda probe heating In other words...

Page 64: ...e 31 2 5 Testing lambda probe signal wiring and activation Note The lambda probe signal is monitored by the self diagnosis system Interrogate fault memory Page 4 If a fault related to the lambda probe...

Page 65: ...tions for open circuits Connector on wiring har ness socket Test box V A G 1598 31 Socket 3 51 4 70 Resistance in wiring max 1 5 Test wires on 4 pin connector for short circuits with each other Connec...

Page 66: ...age 30 Test the following wiring connections for open circuits Connector on wiring har ness socket Test box V A G 1598 31 Socket 3 12 4 13 Resistance in wiring max 1 5 Test wires on 4 pin connector fo...

Page 67: ...ntact between the lambda probe wire and the exhaust pipe 3 Testing intake manifold change over function 3 1 Testing intake manifold change over function This test should only be carried out if the veh...

Page 68: ...ld change over function should be activated display zone 4 Display zones 1 2 3 4 Display Group 95 Intake manifold change over with vehicle being driven Display xxxx rpm x xx ms xxx x C Stage 1 Indicat...

Page 69: ...be heard and felt After 1 minute the final control diagnosis is terminated If the valve does not click switch off the ignition Unplug connector from intake manifold change over valve N156 Measure res...

Page 70: ...in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change over valve Current flow diagrams Electrical fault finding and Fitting locations binder If the voltage s...

Page 71: ...tructions and leaks Remove intake manifold change over valve Reconnect valve to wiring harness Perform final control diagnosis and activate intake manifold change over valve Page 15 Final control diag...

Page 72: ...d held vacuum pump V A G 1390 to vacuum unit Operate hand held vacuum pump and check whether change over function is working Test vacuum unit for leaks The vacuum unit should not return to the rest po...

Page 73: ...m V A G 1594 Repeat final control diagnosis If the diode test lamp now flashes during the final control diagnosis Fit a new secondary air inlet valve 6 Cylinder engine Mechanics Repair group 26 Second...

Page 74: ...ams Electrical fault finding and fitting locations binder 4 3 Testing secondary air pump relay J299 Note The secondary air pump relay is located in the electronics box in the plenum chamber Connect ve...

Page 75: ...low diagrams Electrical fault finding and fitting locations binder If the fuse is not faulty Note The secondary air pump relay is located in the electronics box in the plenum chamber Remove secondary...

Page 76: ...from solenoid valve 1 for activated charcoal filter N80 Connect an auxiliary hose to one of the connections on the ACF valve Connect vehicle diagnostic testing and information system VAS 5051 or fault...

Page 77: ...ained Renew solenoid valve for activated charcoal filter system N80 If the specification is attained Test voltage supply Page 73 Testing power supply to solenoid valve Note The ACF valve receives its...

Page 78: ...ay Page 42 If the diode test lamp lights up test activation Page 74 Testing activation of ACF solenoid valve Connect diode test lamp V A G 1527 between sockets 1 positive and 2 of plug connector Start...

Page 79: ...t 2 64 If the diode test lamp does not flash Test for short to positive or open circuit in the following wiring connections 2 pin connector on wiring harness socket Test box V A G 1598 31 socket 2 64...

Page 80: ...simply a combination of two or three components but rather a complete system comprising all the elements that together determine the position of the throttle valve and also control and monitor it For...

Page 81: ...by entering address word 01 Page 2 When doing this the ignition must be switched on Indicated on display Rapid data transfer HELP Select function XX Press keys 0 and 4 for the function Introduction of...

Page 82: ...Display zones 1 2 3 4 Display Group 60 Adaption of throttle valve control part with ignition on Display xxx xxx Indicates Throttle valve angle angle sender 1 Throttle valve angle angle sender 2 Learni...

Page 83: ...valve control part Test fuse for throttle valve control part Current flow diagrams Electrical fault finding and Fitting locations binder If the fuse is OK Unplug connector from throttle valve control...

Page 84: ...throttle valve control part 6 6 Notes on EPC warning lamp fault warning lamp for electronic throttle in dash panel insert EPC stands for Electronic Power Control and refers to the electronic throttle...

Page 85: ...tly of the other redundancy principle Both senders are located in a single housing Connect vehicle diagnostic testing and information system VAS 5051 or fault reader V A G 1551 and select engine elect...

Page 86: ...oup 20 Servicing accelerator linkage Servicing accelerator linkage Testing voltage supply to accelerator position senders Remove storage compartment on driver s side General body repairs Interior Repa...

Page 87: ...s signals from the brake light switch and also the brake pedal switch This means that if the brakes are operated when the accelerator pedal is held at a constant position the engine speed is immediate...

Page 88: ...splay zones 1 2 3 4 Display group 66 Signals to engine control unit with ignition on Display 0 km h 0 0 1 1 xxx km h 0 0 0 0 Indicates Actual speed Switch positions Specified speed Switch positions fo...

Page 89: ...connect to the engine control unit itself Page 30 Test the following wiring connections for open circuits and short to positive or earth 4 pin connector on wiring harness socket Test box V A G 1598 31...

Page 90: ...Actual speed Switch positions Specified speed Switch positions for cruise control system Range off 0 on 1 off 0 on 1 Specification 0 0 0 0 Note Relevance of figures Page 86 Depress clutch pedal Releva...

Page 91: ...on Connect hand held multimeter voltage range between the following sockets on the connector 2 pin connector on wiring harness socket Specification 1 earth Battery voltage If specification is obtained...

Page 92: ...its If one of the control units indicates a fault Test for open circuit or short circuit between engine control unit and the control unit concerned Current flow diagrams Electrical fault finding and F...

Page 93: ...w Compr OFF Switch on the air conditioner by pressing the Auto button The compressor should run display zone 4 Set air conditioner to maximum hot cold air output display zone 3 Display zones 1 2 3 4 D...

Page 94: ...arbox control unit and or dash panel insert Check that multi pin connectors for control units are properly seated Connect vehicle diagnostic testing and information system VAS 5051 or fault reader V A...

Page 95: ...box control unit ABS control unit and dash panel insert check Part Nos and coding If the correct control units are installed test the CAN data bus system Testing a two wire bus system Three or more co...

Page 96: ...l unit 3 3 No message from control unit 2 Switch off ignition Disconnect the control units which are linked by the bus wires and check whether there is an open circuit in one of the bus wires Current...

Page 97: ...e all the control units which communicate via the CAN data bus are disconnected The ignition is switched off Connect one of the control units Connect fault reader V A G 1551 Switch on the ignition and...

Page 98: ...nd ignition system the following must be noted Do not touch or disconnect ignition wiring when the engine is running or being turned at starter speed The ignition must be switched off before connectin...

Page 99: ...ent Copyright by AUDI AG 1 5 Removing and installing parts of the ignition system 1 Spark plug 30 Nm Remove and install with 3122B 2 Spark plug connector 3 Spacer sleeve 4 Rubber grommet 5 10 Nm 6 Ign...

Page 100: ...opyright by AUDI AG 7 Connector Black 5 pin 8 3 pin connector for knock sensors Contacts gold plated 9 20 Nm Tightening torque influences the function of the knock sensor 10 Knock sensor 2 G66 Cylinde...

Page 101: ...2 14 25 Nm 15 Washer Conical 16 Rotor ring For Hall sender When installing note fixing arrangement 17 Connector Black 3 pin For Hall sender G40 or G163 18 Hall sender G163 Cylinder bank 1 1 6 Testing...

Page 102: ...gnition cables from spark plugs Connect hand held multimeter V A G 1526 between the two spark plug connectors for the ignition circuit which is to be tested Specification 16 27 k for each measurement...

Page 103: ...lectrical fault finding and Fitting locations Testing power supply to ignition coils Test requirement Fuse for ignition coils OK Connect diode test lamp V A G 1527 between engine earth and contact 1 p...

Page 104: ...e diode test lamp does not flash Test wiring Testing wiring Connect test box V A G 1598 31 to wiring harness for engine control unit Do not connect to the engine control unit itself Page 30 Test wirin...

Page 105: ...Before carrying out the test make sure that the sender is correctly installed and firmly seated Unplug connector for engine speed sender grey connector Connect hand held multimeter V A G 1526 resista...

Page 106: ...ender connector to engine control unit for open circuit and or short circuit to positive or earth 3 pin connector on wiring harness contact Socket on test box V A G 1598 31 1 screening 108 2 earth wir...

Page 107: ...p 4 Battery voltage with engine idling Display xxxx rpm xx xxx V xxx x C xxx x C Indicates Engine speed Battery voltage Coolant temperature Intake air temperature Range min 550 rpm max 6800 rpm min 0...

Page 108: ...d in the fault memory the following tests must be carried out Possible cause of fault Fault remedy Fault message relating to all cylin ders Poor fuel quality Change to higher quality fuel see Owner s...

Page 109: ...nd 2 3 Specification There must be no contact between the wires infinity If there is any contact between the wires fit a new knock sensor If there is no short circuit test wiring for knock sensors Tes...

Page 110: ...control unit produces one spark per crankshaft revolution for each cylinder The fact that the injection system is one revolution out of phase does not have any noticeable effect on the fuel injection...

Page 111: ...p does not flash test the voltage supply Test voltage supply for Hall sender Unplug connector from the relevant Hall sender Switch ignition on Connect hand held multimeter V A G 1526 voltage measureme...

Page 112: ...en circuit and or short circuit to positive or earth Hall sender G40 Bank 2 3 pin connector on wiring harness socket Test box V A G 1598 31 sock et 1 positive 98 2 signal 86 3 earth 108 Hall sender G1...

Page 113: ...ase positions of Hall senders Bank 1 and Bank 2 with engine idling Display xxx rpm xx 0 6 crankshaft 0 6 crankshaft Indicates Engine speed Engine load Phase position Bank 1 Phase position Bank 2 Range...

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