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Motronic self-diagnosis
Display groups 00 - 07
Display group 00
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Display zone
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Specified readout
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Equivalent measured value
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Designation
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1
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170...204
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80...105 oC
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Coolant temperature (requirement for basic setting)
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2 1)
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32...48
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1.6...2.4 ms
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Engine load (no consumers switched on)
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2 2)
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20...55
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1.0...2.5 ms
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2 3)
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10...40
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0.5...1.5 ms
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3
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76...96
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720...960 rpm
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Engine speed (no consumers switched on)
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4
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176...212
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12...14.5
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Battery voltage
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5
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0...12
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0...5o
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Throttle valve angle
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6
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112...144
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-4...+4 kg/h
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Idling speed air mass control value (idling speed control)
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7
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112...144
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-4...+4 kg/h
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Learned value for idling speed air mass
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8 1)
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121...137
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-5...+5 %
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Control value for mixture formation (lambda control value)
(only relevant in basic setting and after approx. 1.5 mins)
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8 2)3)
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115...143
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-10...+10 %
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1) Engine code ADP 2) Engine code ADR 3)Engine code AEB
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Display zone
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Specified readout
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Equivalent measured value
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Designation
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9
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243...255
or
0...+13
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-0.64...
+0.64%
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Learned value for mixture formation (lambda learned value) additive
(if outside tolerance, perform test drive)
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10
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118...138
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-8...+8 %
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Learned value for mixture formation (lambda learned value) multiplicative (if outside tolerance, perform test drive)
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1) Engine code ADP 2) Engine code ADR 3)Engine code AEB
Notes on Display zones 9 and 10:
-
◆ In the case of the additive learned value the injection time is changed by a fixed amount which is not dependent on the basic injection time.
-
◆ The multiplicative learned value represents a percentage change in the injection period.
Test table, Display group 00
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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1
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higher than 204
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- Coolant temperature sender -G62
- Wiring connection to Motronic control unit -J220
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- Check G62
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lower than 170
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- Coolant temperature sender -G62
- Wiring connection to Motronic control unit -J220
- Coolant thermostat constantly open
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- Check G62
- Check coolant thermostat
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2
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Greater than the specified value
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- Air conditioner switched on
- Electrical consumers on
- Lambda control at rich or lean stop
- Air conditioner compressor running although air conditioner is off
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- Switch off air conditioner
- Switch off electrical consumers
- Check lambda control
- Check A/C compressor actuation
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Less than specified value
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- Unmetered air downstream of air mass meter
- Unmetered air downstream of throttle valve
- Vacuum hose disconnected
- Fuel pressure regulator
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- Eliminate cause
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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3
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lower than 76
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- Gear engaged (autom. gearbox)
- Engine load from ancillaries
- Throttle valve control part -J338 sticking or defective
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- Move selector lever to "P" or "N"
Eliminate load (air conditioning system/power steering/alternator)
Check throttle valve control part -J338
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higher than 96
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- Idling speed switch -F60 not closed/defective
- Large quantity of unmetered air (cannot be compensated by idling stabilisation)
- Throttle valve control part -J338 sticking or defective
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- Interrogate the fault memory and check/adjust idling switch
Eliminate air leak
Check throttle valve control part -J338
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4
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lower than 176
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- Alternator defective, battery heavily discharged
- High load on electrical system shortly after starting engine due to high charge current and load from ancillaries
- Contact resistance in the positive supply or ground connection for Motronic control unit
- Current drain with ignition off
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- Check voltage, charge battery
Increase engine speed for several minutes and switch off ancillaries
Check power supply to Motronic control unit
Eliminate current drain
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higher than 212
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- Voltage control on alternator defective
- Excess voltage from assisted start or high speed charger
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- Check voltage; if necessary, fit a new voltage regulator.
Interrogate fault memory
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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5
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lower than 0
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- Not possible
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_______________________________
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higher than 12
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- Basic setting of throttle valve control part not performed
- Throttle valve potentiometer in throttle valve control part defective
- Throttle cable setting not OK
- Throttle valve mechanism sticking
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- Perform basic setting of throttle valve control part =>Page
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6
and
7
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lower than 118
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- Unmetered air downstream of throttle valve
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- Eliminate air leak
- Notes on Display group 05,
Display zone 3
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higher than 128
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- Increased engine load due to ancillaries
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- Eliminate load, switch off ancillaries
- Notes on Display group 05,
Display zone 3 => Page 01-77
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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8
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lower than 121
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- Engine running too rich, lambda control in "lean" direction
- Large quantity of fuel from ACF system (not with basic setting)
- Leak in vacuum hose for fuel pressure regulator
- Lambda learned values at stop
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- Depress accelerator briefly at 20 sec intervals until learning procedure is finished
=> Display group 06, Display zone 3
- Replace vacuum hose
- Check lambda learned values, Display group 08 => Page 01-83
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higher than 137
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- Engine running too lean, lambda control enriches mixture
- Unmetered air
- Injectors defective
- Lambda learned values at stop
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- Eliminate air leak
- Check injection quantity
=> Page 01-83
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Readout fluctuates
or remains
constant at 128
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- Fuel reserve too low
- Lambda mixture control is on open loop control
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- At least 10 l fuel in tank - Display group 06, note on Display zone 3
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9
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lower than 243
or
higher than 13
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- =>Display group 08, Display zones 2 and 3
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10
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lower than 118
or
higher than 138
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- =>Display group 08, Display zones 2 and 3
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Display group 01, basic function
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Indicated on display
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Specified readout
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Designation
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Read measured value block 1
1 2 3 4
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760...960 rpm
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1 = Engine speed (shown in increments of 40 rpm)
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1) 1.6...2.4 ms
2) 1.0...20.5 ms
3) 0.5...1.5 ms
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2 = Engine load (injection period per revolution)
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0...5 <o
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3 = Throttle valve angle
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12 oBTDC
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4 = Ignition angle
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1) Engine code ADP 2) Engine code ADR 3) Engine code AEB
Test table, Display group 01
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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1
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Less than 760 rpm
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- Gear engaged (autom. gearbox)
- Engine load from ancillaries
- Throttle valve control part -J338 sticking or defective
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- Move selector lever to "P" or "N"
Eliminate load (air conditioning system/power steering/alternator)
Check throttle valve control part -J338
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Greater than 960 rpm
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- Idling speed switch -F60 not closed/defective
- Large quantity of unmetered air (cannot be compensated by idling stabilisation)
- Throttle valve control part -J338 sticking or defective
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- Interrogate the fault memory and check/adjust idling switch
Eliminate air leak
Check throttle valve control part -J338
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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2
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Less than specified value
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- Technically not possible*
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__________________________________
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Greater than specified value
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- Poor idling (not running on all cylinders)
- Air mass meter -G70 defective
- Throttle valve control part -J338 defective
- Electrical consumers on
- Steering wheel at full lock
- Gear engaged (autom. gearbox)
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- Injector or spark plugs defective
Interrogate fault memory
Check throttle valve control part -J338
Switch off the consumers
Centre steering wheel
Move selector lever to "P" or "N"
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*) Lower values can only occur when vehicle is on overrun.
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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3
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Less than 0 <o
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- Not possible
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_________________________________
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Greater than 5 <o
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- Basic setting of throttle valve control part -J338 not performed
- Throttle valve potentiometer in throttle valve control part -J338 defective or incorrectly set
- Throttle cable setting
- Throttle valve mechanism sticking
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- Perform basic setting of throttle valve control part -J338
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4
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Lower than 12oBTDC
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- Electrical consumers on
- Steering wheel at full lock
- Gear engaged (auto. gearbox)
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- Switch off the consumers
Centre steering wheel
Move selector lever to "P" or "N"
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Greater than 12oBTDC
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- Not possible
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__________________________________
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Notes on Display zone 3:
-
◆ When accelerator pedal is fully depressed, the display value is between approx. 85...90 <o.
-
◆ The following fixed substitute value appears as soon as a fault is detected in the throttle valve potentiometer:
- Engine code ADP: 45 <o
- Engine code ADR: 35 <o
- Engine code AEB: 45 <o
Display group 02, basic function
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Indicated on display
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Specified readout
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Designation
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|
Read measured value block 2
1 2 3 4
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760...960 rpm
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Display zone 1 = engine speed (shown in increments of 40 rpm)
|
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ADP: 1.6..2.4 ms
ADR: 1.0..2.5 ms
AEB: 0.5..1.5 ms
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Display zone 2 = theoretical injection period per crankshaft
revolution (engine load)
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ADP: 2.0...3.5 ms
ADR: 2.0...5.0 ms
AEB: 1.5...3.0 ms
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Display zone 3 = corrected injection period per engine cycle
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ADP: 2.5...4.5 g/s
ADR: 2.0...4.0 g/s
AEB: 1.8...4.0 g/s
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Display zone 4 = intake air mass
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Test table, Display group 02
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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1
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|
- See Display group 01, Display zone 1
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2
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- See Display group 01, Display zone 2
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Note on Display group 2, basic function:
-
◆ Display zone 2 shows the injection period which corresponds to the intake air mass and the engine load when idling. This value is a purely calculated, theoretical value which, because of the processor technology, only relates to a single crankshaft revolution. The engine load when idling is the load created by the internal friction which the engine has to overcome and the power required to drive the ancillaries. The intake air mass is shown in Display zone 4.
-
◆ Display zone 3, on the other hand, shows the injection period for a complete engine cycle, i.e. two crankshaft revolutions.
-
◆ However it is the corrected actual injection period which is shown in Display zone 3 and not the doubled value of Display zone 2. Correction of variables such as:
- Lambda control
- Fuel supply from activated charcoal filter
- Air density, air temperature
- Vehicle voltage (quicker / slower opening of the injectors)
-
◆ For example, if the engine draws in unmetered air, only the calculated value in Display zone 2 should change (injection period per crankshaft revolution). The lambda control ensures that the actual injection period per engine cycle remains at the specified value.
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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3
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Less than specified value
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- Large quantity of fuel from the ACF system
- Wrong injectors installed (delivery rate too high)
|
- Check solenoid valve for activated charcoal filter
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Greater than specified value
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- Increased engine load due to electric consumers, air conditioner or engaged gear, power-assisted steering at full lock
|
- Eliminate load
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4
|
Less than specified value
|
- Large quantity of unmetered air between intake manifold and air mass meter
|
- Eliminate air leak
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Greater than specified value
|
- Gear engaged (autom. gearbox)
- Engine load from ancillaries
|
- Move selector lever to "P" or "N"
Eliminate load (air conditioning system/power steering/alternator)
|
Display group 03, basic function
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|---|
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Indicated on display
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Specified readout
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Designation
|
|
Read measured value block 3
1 2 3 4
|
760...960 rpm
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1 = Engine speed (shown in increments of 40 rpm)
|
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|
12...140.5 V
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2 = Battery voltage
|
|
|
80...105 oC
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3 = Coolant temperature
|
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|
...oC
|
4 = Intake air temperature
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Test table, Display group 03
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Display zone
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Readout on V.A.G 1551
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Cause of fault
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Fault remedy
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|
1
|
|
- See Display group 01, Display zone 1
|
|
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2
|
Less than 12 V
|
- Alternator defective, battery heavily discharged
- High load on electrical system shortly after starting engine due to high charge current and load from ancillaries
- Contact resistance in the positive supply or ground connection for Motronic control unit
- Current drain with ignition off
|
- Check voltage, charge battery
Increase engine speed for several minutes and switch off ancillaries
Check power supply to Motronic control unit
Eliminate current drain
|
|
|
Greater than 14.5 V
|
- Voltage control on alternator defective
- Excess voltage from assisted start or high speed charger
|
- Check voltage; if necessary, fit a new voltage regulator.
Interrogate fault memory
|
|
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|---|
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Display zone
|
Readout on V.A.G 1551
|
Cause of fault
|
Fault remedy
|
|
3
|
Less than 80 oC
|
- Engine too cold
- Sender for coolant temperature or wiring to Motronic control unit
|
- Test drive if necessary.
Check -G62
|
|
|
Greater than 105 oC
|
- Radiator dirty
- Radiator fan not working
- Coolant thermostat defective
- Sender for coolant temperature or wiring to Motronic control unit
|
- Clean radiator
Check function
Check coolant thermostat
Check -G62
|
|
41)
|
Constant 19.5 oC
|
- Fault detected on intake air temperature sender -G42
|
- Interrogate fault memory - Page 28-41
|
|
|
Greater than 2)
|
- Intake air temperature sender -G42
|
- Check -G42
|
1) - There is no intake air temperature sender installed for vehicles with engine codes ADP and ADR. A constant value of 19.5 oC is always displayed.
- For vehicles with engine code AEB, the value measured by the intake air temperature sender is displayed.
2) when vehicle is running, up to 24 oC above ambient temperature
when vehicle is stationary, depending on the heat accumulation in the engine and the standing time, up to 110 oC
Note on Display zone 3:
The Motronic control unit operates with voltages of between 10 and 15 V. However, voltages below 12 V or above 14.5 V indicate a defect.
Display group 04, idling speed adjustment
|
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|---|
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Indicated on display
|
Specified readout
|
Designation
|
|
Read measured value block 4
1 2 3 4
|
0...5 <o
|
1 = Throttle valve angle
|
|
|
-1.1...5+1.1 g/s
|
2 = Idling air mass, learned (no gear engaged on automatic)
|
|
|
-1.7...+1.7 g/s
|
3 = Idling air mass, learned, with gear engaged on automatic
|
|
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Idling
|
4 = Operating status
|
Test table, Display group 04
|
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|---|
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Display zone
|
Readout on V.A.G 1551
|
Cause of fault
|
Fault remedy
|
|
1
|
|
- See Display Group 01, Display zone 3
|
|
|
2
|
Greater than -1.1 g/s
|
- Unmetered air downstream of throttle valve
|
- Eliminate air leak
|
|
|
Greater than +1.1 g/s
|
- Large load from ancillaries
- Constriction/foreign matter in intake area
|
- Switch off air conditioner and electrical consumers
- Eliminate constriction or foreign body
|
Note on Display zone 1:
When the accelerator pedal is fully depressed, the display value is between approx. 85...90 <o.
Note on Display zones 2 and 3:
The display shows how far the learned values of the idle stabilisation have "drifted away" from the pre- programmed mean value. With a new engine, the display will show a positive value because of the greater friction; if the engine has been run in it will show a negative value. A value of - 1.1 g/s combined with an excessively low value in Display group 05, Display zone 3, indicates the presence of unmetered air.
-
◆ The value displayed is not measured by the air mass meter but calculated from information from the throttle valve potentiometer.
-
◆ On vehicles with a manual gearbox Display zone 3 always displays 0.
Note on Display zone 4:
The following operating statuses are displayed:
-
◆ Idling
-
◆ Part throttle
-
◆ Full throttle
-
◆ Overrun
-
◆ Enrichment (full throttle enrichment)
Display group 05, idling stabilisation
|
|
|---|
|
Indicated on display
|
Specified readout
|
Designation
|
|
Read measured value block 5
1 2 3 4
|
820...900 rpm
|
1 = Engine speed (actual)
|
|
|
860 rpm
|
2 = Engine speed (specified)
|
|
|
-10...+10 %
|
3 = Idling speed control
|
|
|
1) 2.5...4.5 g/s
2) 2.0...4.0 g/s
3) 1.8...4.0 g/s
|
4 = Air mass
|
1) Engine code ADP 2) Engine code ADR 3) Engine code AEB
Note on Display zone 1:
-
◆ The actual engine speed is displayed in increments of 10 (max. 2550 rpm).
-
◆ Fault cause and fault remedy =>Display group 2, Display zone 1.
Note on Display zone 2:
The specified engine speed set by the Motronic control unit is displayed.
Note on Display zone 3:
During idling, the air mass requirement varies with changing load conditions, even though the engine speed is constant. The change in air mass during idling is shown as a percentage. As soon as the change has been compensated by the idle stabilisation learning process, the mean value is restored. The amount of deviation from the mean value depends on the extent of the load change (e.g. as a result of switching electrical consumers on or off). The learning process proceeds in small stages each time the idling switch closes. In the event of a large deviation, several stages are required. To do this, depress the accelerator pedal briefly in 20 second intervals (brief burst of throttle). Every burst of throttle moves the learning process along a further step.
The deviation that has "drifted away" then appears in Display group 04, Display zone 2. The idling speed control values remain outside tolerance if the learned values in Display group 04, Display zone 2 have run on to the stop.
Stop values:
Engine code ADP: -1.13 or +1.42 g/s
Engine code ADR: -1.70 or +1.70 g/s
Engine code AEB: -1.13 or +1.13 g/s
Note on Display zone 4:
-
◆ The display shows the air mass measured by the air mass meter.
-
◆ If the vehicle is in emergency running mode due to a fault in the throttle valve control part, then the engine runs without idling stabilisation with an increased idling speed (approx. 110...1300 rpm) caused by the emergency running gap. The air throughput is roughly 4.5...5.5 g/s.
Display group 06, idling stabilisation
|
|
|---|
|
Indicated on display
|
Specified readout
|
Designation
|
|
Read measured value block 6
1 2 3 4
|
820...900 rpm
|
1 = Engine speed (display in increments of 10; max. 2550 rpm)
|
|
|
-10...+10 %
|
2 = Idling speed control
|
|
|
1) -5...+5 %
2) -10...+10 %
3) -10...+10 %
|
3 = Lambda control
|
|
|
12 oBTDC
|
4 = Ignition angle
|
1) Engine code ADP 2) Engine code ADR 3) Engine code AEB
Test table, Display group 06
|
|
|---|
|
Display zone
|
Readout on V.A.G 1551
|
Cause of fault
|
Fault remedy
|
|
1
|
|
- See Display group 01, Display zone 1
|
|
|
2
|
|
- See Display group 05, Display zone 3
|
|
|
|
|---|
|
Display zone
|
Readout on V.A.G 1551
|
Cause of fault
|
Fault remedy
|
|
3
|
Outside tolerance range
|
Negative display - engine too rich, consequence: Lambda control produces leaner mixture
Positive display ("+" is not displayed) - engine too lean, consequence: Lambda control produces richer mixture
- Unmetered air
- Injector defective
- Lambda learned values (Display group 00 or 08) at stop
|
- Wait 30 seconds until the display
has stabilised
- Eliminate air leak
- Check injection quantity
|
|
4
|
|
- See Display group 01, Display zone 4
|
|
Note on Display zone 3:
The display should fluctuate around 0. If a constant value of 0 is displayed then the lambda control has switched from closed loop to open loop control because a fault is present in the lambda control =>Interrogate fault memory or check Display group 21, Display zone 4.
Display group 07, lambda control and ACF system
|
|
|---|
|
Indicated on display
|
Specified readout
|
Designation
|
|
Read measured value block 7
1 2 3 4
|
1) -5...+5 %
2) -10...+10 %
3) -10...+10 %
|
1 = Lambda control
|
|
|
-0.1 ... +1.1 V
|
2 = Lambda probe voltage
|
|
|
0...99
|
3 = Duty cycle, solenoid valve 1 for activated charcoal filter
|
|
|
0.3...1.2
|
4 = Lambda correction factor with active tank breather
|
1) Engine code ADP 2) Engine code ADR 3) Engine code AEB
Note on Display zone 1:
=>Display group 06, Display zone 3
Note on Display zone 2:
The voltage signal for "Mixture rich" (low level of residual oxygen) is between about 0.7 and 1.1 V (referenced to reference ground).
The voltage signal for "Mixture lean" (high residual oxygen) is between about -0.1..+0.3 V (referenced to reference earth).
During the transition from "rich" to "lean" and vice versa (λ= 1.0), there is a voltage jump from 0.7...1.1 V to -0.1...0.3 V or vice versa.
Because of the sharp voltage jump the lambda control cannot maintain a constant ideal mixture composition of λ= 1.0. The system fluctuates continuously between "slightly too lean" and "slightly too rich".
Note on Display zone 3:
A duty cycle of 0 means that ACF solenoid valve 1 is closed. At a duty cycle of 99 the solenoid valve is fully open.
Note on Display zone 4:
-
◆ At a display value of 0.3 the engine is receiving a very rich mixture from the ACF system. - The lambda control therefore has to reduce the injection quantity to 30%.
-
◆ At a display value of 1.0 the ACF system is either delivering an ideal mixture (no intervention towards lean or rich required), or the ACF valve is closed (adaptation =>Display group 08, Display zone 4).
-
◆ If the value displayed is 1.01 ... 1.2 then the mixture coming from the ACF system is too lean. - The lambda control therefore has to enrich the mixture.
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