Self-diagnosis of Motronic system

Read measured value block: Display Groups 11 to 99

Display Group 11 - Fuel consumption:

Display Group 12 - Knock control:

Display Group 13 - Knock control:

Display Group 14 - Knock control:

Display Group 15 - Knock control:

Notes on Display Groups 12, 13, 14 and 15:

l

◆

The knock control operates at engine loads of 40% or more.

l

◆

At engine loads of more than 40% the display will show the current (instantaneous) ignition timing retardation values. At engine loads

of less than 40% the display will show the last values used (constant readout).

l

◆

If there is audible knocking and no perceptible ignition timing retardation, increase the engine speed to above 3500 rpm for 5 seconds

in order to activate the knock sensor fault recognition (diagnosis) function.

l

◆

If there is a significant difference between the ignition timing retardation value for one of the cylinders and the values for the other

Read measured value block 11

⇒

◂

Indicated on display

620...860

rpm

1.0...2.5

ms

0

km/h

0.8...1.8

ltr./h

Fuel consumption:

The specified value shown on the display relates only to idling without

additional load from ancillaries (automatic gearbox, air conditioner,

alternator, power steering pump).

Not for measuring fuel consumption in litres/100 km

Road speed

Engine load

Idling speed shown in steps of 40 rpm

Four-wheel drive: 620...740 rpm

Front-wheel drive: 740...860 rpm

Read measured value block 12

⇒

◂

Indicated on display

0...6800

rpm

0...12°

cr/shaft

0...12°

cr/shaft

0...12°

cr/shaft

Ignition timing retardation by knock control, cylinder 3

Ignition timing retardation by knock control, cylinder 2

Ignition timing retardation by knock control, cylinder 1

Engine speed

Read measured value block 13

⇒

◂

Indicated on display

0...10 ms

0...12°

cr/shaft

0...12°

cr/shaft

0...12°

cr/shaft

Ignition timing retardation by knock control, cylinder 3

Ignition timing retardation by knock control, cylinder 2

Ignition timing retardation by knock control, cylinder 1

Engine load

Read measured value block 14

⇒

◂

Indicated on display

0...6800

rpm

0...12°

cr/shaft

0...12°

cr/shaft

0...12°

cr/shaft

Ignition timing retardation by knock control, cylinder 6

Ignition timing retardation by knock control, cylinder 5

Ignition timing retardation by knock control, cylinder 4

Engine speed

Read measured value block 15

⇒

◂

Indicated on display

0...10 ms

0...12°

cr/shaft

0...12°

cr/shaft

0...12°

cr/shaft

Ignition timing retardation by knock control, cylinder 6

Ignition timing retardation by knock control, cylinder 5

Ignition timing retardation by knock control, cylinder 4

Engine load

Strona 1 z 7

cylinders, the following faults are possible:

- Loose ancillaries

- Corrosion on plug connector

- Engine damage (e.g. oil burning because of defective piston)

l

◆

If the ignition timing retardation values for all the cylinders are high, the following faults are possible:

- Corrosion on plug connector

- Wrong tightening torque (should be 20 Nm)

- Open circuit in wiring

- Knock sensor defective

- Loose ancillaries

- Poor-quality fuel (less than RON 95)

Display Group 16 - Knock control:

Notes on Display Group 16:

l

◆

As soon as knocking is detected, the knock control must retard the ignition timing in order to prevent damage to the engine.

l

◆

However, retardation of the ignition timing increases the temperature of the exhaust emissions, which means there is a risk of

overheating in the catalytic converter.

l

◆

To prevent this overheating, the mixture is enriched when the total ignition timing retardation exceeds about 10 °cr/shaft at full

throttle. This has the effect of reducing the temperature of the exhaust emissions.

Display Group 17 - Knock sensor:

Display Group 18 - Knock sensor:

Notes on Display Groups 17 and 18:

l

◆

If no faults are found in the knock sensor or in the wiring or connectors, check the engine for loose ancillaries or damage (see Display

Groups 12, 13, 14 and 15).

l

◆

At high engine speeds the displayed signal voltage for the knock sensors can reach 5.1 Volt.

l

◆

If there is more than 50 % difference between the smallest and largest knock sensor signal, the cause could be corrosion on the

Read measured value block 16

⇒

◂

Indicated on display

0...6800

rpm

0...10 ms

-20...+40°

A/BTDC

0.0...72.0°

cr/shaft

Total ignition timing retardation, cylinders 1 to 6

Ignition timing

Engine load

Engine speed

Read measured value block 17

⇒

◂

Indicated on display

620...860

rpm

0.50...1.40

V

0.50...1.40

V

0.50...1.40

V

Knock sensor voltage signal, cylinder 3

Knock sensor voltage signal, cylinder 2

Knock sensor voltage signal, cylinder 1

Idling speed shown in steps of 40 rpm

Four-wheel drive: 620...740 rpm
Front-wheel drive: 740...860 rpm

Read measured value block 18

⇒

◂

Indicated on display

620...860

rpm

0.50...1.40

V

0.50...1.40

V

0.50...1.40

V

Knock sensor voltage signal, cylinder 6

Knock sensor voltage signal, cylinder 5

Knock sensor voltage signal, cylinder 4

Idling speed shown in steps of 40 rpm

Four-wheel drive: 620...740 rpm

Front-wheel drive: 740...860 rpm

Strona 2 z 7

connector.

Display Group 19 - Torque reduction (automatic gearbox):

Notes on Display Group 19:

l

◆

This display group shows how much the ignition timing is reducing the engine torque during gearshifts in order to achieve a smoother

transition between gears.

l

◆

Because the signal is only brief the V.A.G 1551 or 1552 is not always able to detect the ignition timing retardation, and therefore this

may not appear on the display.

l

◆

Display zone 3 shows the engine torque required for the gearshift (specified engine torque).

l

◆

Display zone 4 shows the actual engine torque (torque at clutch).

l

◆

Testing ignition timing retardation during gearshifts => Page

24-106

.

Display Group 20 - Operating conditions:

Note on display zone 3:

l

◆

On vehicles with four-wheel drive the idling speed will increase if the rear window heating or the air conditioner is switched on. On

vehicles with front-wheel drive and no air conditioner the idling speed will increase if the rear window heating is switched on. In each

case, however, this increase will only occur when the accelerator pedal is depressed briefly (blipped).

l

◆

A/C-High = rear window heating switched on, or air conditioner requires high hot/cold air output

A/C-Low = rear window heating / air conditioner switched off

Display Group 21 - Operating conditions for lambda control:

Notes on Display Group 21:

l

◆

If the engine is started at a temperature of less than 15 °C (intake air temperature), the engine control unit will not engage the lambda

control until the coolant temperature reaches 55°C.

l

◆

If the engine is started at a temperature of more than 15 °C (intake air temperature), the lambda control will cut in when the system

recognises that the lambda probe is functioning.

l

◆

When the lambda control is switched off the engine runs according to a map stored in the control unit.

Display Group 22

This display group is for factory use only.

The display values are not relevant for fault-finding in the workshop.

Display Group 23 - Adaption of throttle valve positioner:

Read measured value block 19

⇒

◂

Indicated on display

0...6800

rpm

0.0...10.0

ms

0...410

Nm

-100...300

Nm

Actual engine torque

Required (specified) engine torque

Engine load

Engine speed

Read measured value block 20

⇒

◂

Indicated on display

rpm

Neutral

Gear engag

A/C-High

A/C-Low

Compr.ON

Compr.OFF

Air conditioner compressor ON/OFF

On vehicles with no air conditioner the display will always read

"Compr.OFF".

Air conditioner / rear window heating

Selector lever in Neutral or with gear engaged

On vehicles with manual gearboxes the display will always read "Neutral".

Engine speed shown in steps of 10 rpm

Read measured value block 21

⇒

◂

Indicated on display

rpm

ms

° C

λctrl.OFF

λctrl.ON

Lambda control OFF/ON

Coolant temperature

Engine load

Engine load shown in steps of 40 rpm

Strona 3 z 7

Note on display zone 1:

If the display does not show the specified value, perform adaption of throttle valve control part -J338 => Page

24-83

.

Note on display zone 2, 3 and 4:

The display will show the stop values learned at the last basic setting.

Note on display zones 1, 2, 3 and 4:

If the display still does not show the specified value even after the basic setting has been performed, check the wiring for open circuits or short

circuits and also check the plug connections for dirt or corrosion before fitting a new throttle valve control part.

Relevance of figures in 8-digit number block, display zone 1 (learning requirement):

Display Group 24 - Traction control system (ASR):

Notes on Display Group 24:

l

◆

Display Group 24 is only for vehicles with traction control system (ASR).

l

◆

Vehicles with traction control system (ASR) are identified by the ASR warning lamp on the dash panel insert, or by means of the

ABS/ASR self-diagnosis.

=> Running Gear, Front- and Four-wheel drive; Repair Group 01

This display group shows how much the engine torque is reduced in order to prevent skidding when wheel slip is detected.

The engine control unit informs the ABS/ASR control unit of the actual engine torque. If wheel slip is detected, the ABS/ASR control

Read measured value block 23

⇒

◂

Indicated on display

01000000 72...95 %

60...92%

xxx %

Max. stop of throttle valve positioner -V60

Manual gearbox:18...54%

Automatic gearbox:34...70 %

Emergency running stop of throttle valve positioner -V60

Min. stop of throttle valve positioner -V60

Learning requirement display

X

X

X

X

X

X

X

X

Meaning

(Irrelevant)
Learning process for min. stop of throttle valve positioner

sender -G127

0 = learning process completed and OK

1 = learning process not completed - not OK
Learning process for max. stop of throttle valve positioner

sender -G127

0 = learning process completed and OK

1 = learning process not completed - not OK
Learning process for min. stop of throttle valve

potentiometer -G69

0 = learning process completed and OK

1 = learning process not completed - not OK
Learning process for max. stop of throttle valve

potentiometer -G69

0 = learning process completed and OK

1 = learning process not completed - not OK
(Irrelevant)
Matching of throttle valve potentiometer -G69 to throttle

valve positioner sender -G127

0 = matching process needs to be carried out

1 = matching process completed; match OK
(Irrelevant)

Read measured value block 24

⇒

◂

Indicated on display

0...6800

rpm

0 ... 12

-100...410

Nm

-100...300

Nm

Actual engine torque (MMI)

Required/specified engine torque (MMS)

Torque reduction stages

Engine speed

Strona 4 z 7

unit calculates the required (specified) engine torque and sends a corresponding signal to the engine control unit instructing it to reduce

the engine torque. The torque reduction takes place in 12 separate stages. A feedback signal indicating the actual engine torque then

informs the ABS/ASR control unit how much the engine torque has been reduced.

Notes continued:

l

◆

When the engine is cold (coolant temperature less than 30 °C), small torque reduction stages (1 to 2) are achieved by retarding the

ignition timing and large reduction stages (3 to 12) are achieved by briefly shutting off individual injectors.

l

◆

When the engine is warm (coolant temperature more than 45 °C), the engine torque is reduced both by briefly shutting off individual

injectors and by retarding the ignition timing.

Notes on display zones 3 and 4:

l

◆

Display zone 3 shows the required engine torque as calculated by the ABS/ASR control unit (specified engine torque).

l

◆

Testing specified engine torque signal from ABS/ASR control unit=>Page

24-105

.

l

◆

Display zone 4 shows the actual engine torque (torque at clutch).

l

◆

Testing signal for actual engine torque=>Page

24-104

.

l

◆

When the traction control system (ASR) is not active (i.e. when no torque reduction is required by the ASR), display zone 3 will show

a value that is considerably higher than the maximum possible engine torque value of 300 Nm. This is a purely theoretical value (up to

410 Nm) which has been deliberately set very high for safety purposes in order to make a clear distinction between it and the actual

engine torque. This ensures that the engine control unit will always register the need to reduce the torque.

l

◆

The values in display zones 3 and 4 will gradually settle at the same level during the period in which the traction control system (ASR)

is active.

Display Group 25 - System status:

Display Group 26 - Camshaft timing control:

Display Group 27 - System status and camshaft timing control:

Note on display zone 1:

This display zone shows which systems are being activated by the engine control unit (system status). If the operating conditions (e.g. engine

load, engine speed) for a particular system have been met, the engine control unit will activate it. However, the fact that a system has been

activated does not necessarily indicate that it is functioning.

Relevance of figures in 3-digit number block, display zone 1 (system status):

Read measured value block 25

⇒

◂

Indicated on display

0...6800

rpm

0.0...10.0

ms

X . . . . . X X

(Unallocated)

System status - see Display Group 27

Engine load

Engine speed

Read measured value block 26

⇒

◂

Indicated on display

0...6800

rpm

0.0...10.0

ms

Normal position:

-3.0 ... 6.0 ° cr/shaft

Adjusted position:

16.0 ... 25.0 ° cr/shaft

Camshaft timingcontrol, Bank 2 - see Display Group 27

Camshaft timingcontrol, Bank 1 - see Display Group 27

Engine load

Engine speed

Read measured value block 27

⇒

◂

Indicated on display

X . . . . . X X

Normal position:

-3.0 ... 6.0 ° cr/shaft

Adjusted position:

16.0 ... 25.0 ° cr/shaft

Camshaft timingcontrol, Bank 2

Camshaft timingcontrol, Bank 1

(Unallocated)

System status

X

X

X

Meaning

0 = conditions not met; system not activated
1 = conditions met; system active

Strona 5 z 7

Notesondisplayzones3and4:

l

◆

Thevariablecamshafthasonlytwopositions,i.e.thenormal positionandtheadjustedposition.

Tomovethecamshafttotheadjustedposition,acceleratethevehiclefrom standstill in1stgear.

Displayzones3and4show theactual positionsofthevariablecamshafts.

Ifthecamshafttimingcontrol isactive(seedisplayzone1),displayzones3and4will show whetherthecamshaftpositionshaveinfact

beenadjusted(feedbacksignal).

-Camshaftinnormal position=-3.0...+6.0°cr/shaft

-Camshaftinadjustedposition=16.0...25.0°cr/shaft

l

◆

Ifavalueofbetween6.0°cr/shaftand16.0°cr/shaftappearsindisplayzone3and/or4duringthetestdrive,thismeansthatthe

solenoidvalvesforcamshaftadjustmentaredivertingtheoilpressuretotheappropriatemechanical camshaftadjusterbutthatthe

mechanical adjusterisunabletoreachitsendstopposition(e.g.becauseitisnotmovingfreely).

l

◆

Testingcamshafttimingcontrol=>Page

28-40

.

DisplayGroup95-Basicfunction:

DisplayGroups96and97:

Thesedisplaygroupsareforfactoryuseonly.

Thedisplayvaluesarenotrelevantforfault-findingintheworkshop.

DisplayGroup98-Adaptionofthrottlevalvecontrol part:

Noteondisplayzone4:

ADP.=Adaption.Checkingadaptionofthrottlevalvecontrol part=>Page

24-83

DisplayGroup99-Lambdacontrol:

Notesondisplayzone4:

Camshafttimingcontrol
Intakemanifoldchange-overfunction
(Unall ocated)
Energybalanceforcatalyticconverterheating

Basicsetting95

⇒

◂

Indicatedondisplay

620...860

rpm

1.00....2.50

ms

12.0°BTDC

-40...125

°C

Coolanttemperature-seeDisplayGroup03

Ignitiontiming-seeDisplayGroup01

Enginel oad

Enginespeed

Four-wheel drive:620...740rpm

Front-wheel drive:740...860rpm

Basicsetting98

⇒

◂

Indicatedondisplay

0...5

V

0...5

V

Idling

Partthrot

ADP.runs

ADP.O.K.

ADP

ERROR

Adaptionstate

ADP.=adaptionofthrottlevalvecontrol part

Operatingstate

Voltageofpotentiometerforidlingspeedpositioner

Voltageofthrottlevalvepotentiometer

Readmeasuredvalueblock99

⇒

◂

Indicatedondisplay

rpm

°C

-10...+10

%

λ ctrl. OFF

λctrl. ON

Lambdacontrol OFF/ON

Basic setting 04: λctrl. OFF

Read measured value block 08: λctrl. ON

Lambdacontrol

Coolanttemperature

Enginespeed

Strona 6 z 7

l

◆

Toassistfault-finding,thel ambdamixturecontrol functionisde-activatedwhenDisplayGroup99isselectedin"Basicsetting04"and

activatedwhenitisselectedin"Readmeasuredvalueblock08".

l

◆

Thel ambdamixturecontrol functionisautomaticall yre-activatedbyexitingfrom function04"Basicsetting".

l

◆

Bypressingthekeys4and8ontheV.A.G 1551itispossibletoswitchbackandforthbetweenfunction04"Basicsetting"and

function08"Readmeasuredvalueblock".

Strona 7 z 7