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Measured value blocks
Evaluating measured value blocks, display groups 001 - 003
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Display group 1 -Basic functions-
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Read measured value block 1
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⇒
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[ltrif ] Indicated on display
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xxxx rpm
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xx.x °C
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xx.x %
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xx.x° BTDC
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1
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2
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3
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4
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[ltrif ] Display zones
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Specification
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Evaluation
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Ignition angle
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0...13.5 ° BTDC
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---
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Lambda regulator
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-20...20 %
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Coolant temperature
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80...105 °C
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=> Page 01-67
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-66
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Notes on display zone 2:
The engine control unit will use the intake air temperature as a replacement value for an engine start (start temperature - replacement value) as soon as there is a fault stored in the fault memory, which affects the coolant temperature sender (G62). The temperature then rises according to a model stored in the control unit. When the engine has reached normal working temperature a fixed replacement value will be displayed after a certain period. This fixed value is also dependent upon the intake air temperature.
Notes on display zone 3:
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◆ The display must fluctuate around 0. If constant 0 is displayed, the Lambda regulation has switched from regulation to control, because there is a fault in the Lambda regulation. Interrogate fault memory => Page 01-12
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Display group 1 -Basic functions- for control unit number: 021906258BQ ... CN
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Read measured value block 1
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⇒
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[ltrif ] Indicated on display
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xxxx rpm
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xx.x °C
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x.xx
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xx.x° BTDC
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1
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2
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3
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4
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[ltrif ] Display zones
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Specification
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Evaluation
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Ignition angle
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0...13.5 ° BTDC
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---
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Lambda factor
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0.97... 1.03
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=> Page 01-68
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Coolant temperature
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80...105 °C
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=> Page 01-67
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-66
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Notes on display zone 2:
The engine control unit will use the intake air temperature as a replacement value for an engine start (start temperature - replacement value) as soon as there is a fault stored in the fault memory, which affects the coolant temperature sender (G62). The temperature then rises according to a model stored in the control unit. When the engine has reached normal working temperature a fixed replacement value will be displayed after a certain period. This fixed value is also dependent upon the intake air temperature.
Note on display zone 3:
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◆ If the figures are higher or lower than the specification when the engine is warm this leaning or enriching of the mixture (caused by unmetered air or a defective injection system) can lead to a fault being entered. Interrogate fault memory => Page 01-12
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Evaluating display group 1, display zone 1 - Engine speed (idling speed)
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V.A.G 1551 display
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Possible fault cause
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Fault elimination
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Less than 650 rpm
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- Throttle valve control part sticking or defective
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- Check throttle valve control part
=> Page 24-34
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- Large amount of unmetered air (cannot be compensated for by the idling stabilisation)
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- Check intake air system for leaks
=> Page 24-72
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More than 750 rpm
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- Idling switch not closed/defective
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- Interrogate fault memory, => Page 01-12
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- Large amount of unmetered air (cannot be compensated for by the idling stabilisation)
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- Check intake air system for leaks
=> Page 24-72
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- Throttle valve control part sticking/defective
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- Check throttle valve control part
=> Page 24-34
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- Supply voltage too low, engine tries to reduce charge difference through increased idling speed
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- Check alternator
=> Page 01-71
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- Air conditioner operating too long at idling speed
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- Switch off air conditioner
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Evaluating display group 1, display zone 2 - Coolant temperature
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Appears on display
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Possible fault cause
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Fault elimination
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Less than 80 °C
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- Engine too cold
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- If necessary carry out test drive
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- Coolant temperature sender or wiring to engine control unit
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- Check coolant temperature sender
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More than 105 °C
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- Radiator soiled
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- Clean radiator
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- Radiator fan not functioning
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- Check function
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- Thermostat defective (does not open)
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- Check thermostat
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- Coolant temperature sender or wiring to engine control unit
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- Check coolant temperature sender
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Evaluating display group 1, display zone 3 - Lambda regulator
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Appears on display
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Possible fault cause
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Fault elimination
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Outside tolerance range
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- Minus range: Mixture too rich, Lambda control weakens mixture
- Positive range: Mixture too lean, Lambda control enrichens mixture
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- Wait 30 seconds until the display has stabilised
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- Unmetered air
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- Check intake system for leaks
=> Page 24-72
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- Injector defective
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- Check injection rate => Page 24-79
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Display group 2 -Basic functions-
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Read measured value block 2
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⇒
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[ltrif ] Indicated on display
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xxxx rpm
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x.xx ms
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xx.xx V
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xxxxxxxx
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1
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2
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3
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4
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[ltrif ] Display zones
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Specification
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Evaluation
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Exhaust gas recirculation
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EGR active
EGR not active
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---
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Control unit voltage supply
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12.000...14.500 V
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=> Page 01-71
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Injection period
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1.0...3.5 ms
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=> Page 01-70
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-66
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Notes on display zone 4:
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◆ "EGR not active" will be displayed on vehicles with a throttle valve control part but not fitted with exhaust gas recirculation.
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◆ If no exhaust gas recirculation is fitted, for control unit number 021906258BQ ... CN 182.0 °C or 217.0 °C will be displayed constantly.
Evaluating display group 2, display zone 2 - Injection period
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Appears on display
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Possible fault cause
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Fault elimination
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Less than 1.00 ms
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- Large amount of fuel from the activated charcoal filter system
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- Check activated charcoal filter solenoid valve
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- Incorrect injectors with greater throughput installed
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- Check injection rate => Page 24-79
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- Fuel pressure too high
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- Check fuel pressure regulator
=> Page 24-69
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More than 3.50 ms
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- Increased engine load due to electric consumers, air conditioner, gear selected or P.A.S. steering on full lock
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- Eliminate increased load (air conditioner, power assisted steering etc.)
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Evaluating display group 2, display zone 3 - Control unit voltage supply
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Appears on display
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Possible fault cause
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Fault elimination
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Less than 12.000 V
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- Generator defective, battery heavily discharged
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- Check voltage, charge battery
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- Battery heavily loaded shortly after starting due to high charging current and current consumers
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- Increase revs slightly for a few minutes and switch off current consumers
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- Transfer resistance in the current supply or the engine control unit earth connection
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- Check engine control unit voltage supply => Page 24-108
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- Current draw when ignition is off
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- Eliminate current draw
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More than 14.500 V
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- Voltage regulator in alternator defective
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- Check voltage, replace regulator if necessary
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- Excess voltage due to jump starting or quick charging unit
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- Interrogate fault memory => Page 01-12
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Display group 3 -Basic functions-
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Read measured value block 3
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⇒
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[ltrif ] Indicated on display
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xxxx rpm
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x.xx ms
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x <°
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xxx.x °C
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1
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2
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3
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4
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[ltrif ] Display zones
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Specification
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Evaluation
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Intake air temperature
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-45...108.5 °C
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Throttle valve angle
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1...5 <°
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=> Page 01-73
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Injection period
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1.0...3.5 ms
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=> Page 01-70
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-66
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Note on display zone 3:
When the throttle valve angle displays 0 at idling speed, the engine control unit recognises "overrun". Match throttle valve control part to engine control unit => Page 24-116
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Note on display zone 4:
Exact information on specifications is not possible as the display is largely dependent on the ambient temperature.
Evaluating display group 3, display zone 3 - Throttle valve angle
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Appears on display
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Possible fault cause
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Fault elimination
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More than 5 <°
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- Engine control unit not matched to throttle valve control part
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- Perform matching to throttle valve control part => Page 01-12
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- Throttle valve potentiometer in throttle valve control part defective
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- Check throttle valve control part
=> Page 24-34
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- Accelerator cable adjustment
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- Adjust accelerator cable
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- Throttle valve sticking
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- Eliminate cause
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Note:
If the accelerator pedal is floored the value will be 75...95 <°.
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Display group 3 -Basic functions- for control unit number: 021906258BQ ... CN
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Read measured value block 3
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⇒
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[ltrif ] Indicated on display
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xxxx rpm
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x.xx %
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xx <°
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xxx.x °C
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1
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2
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3
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4
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[ltrif ] Display zones
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Specification
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Evaluation
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Intake air temperature
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-45...108.5 °C
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Throttle valve angle
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9...19 <°
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---
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Engine load
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1.0...4.0 %
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---
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-66
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Note on display zone 3:
If the throttle valve angle is outside of the specification at idling speed, check the adjustment of the accelerator cable and then the operating modes => display group 4 display zone 4. Also check the throttle valve potentiometer => Page 24-51
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Note on display zone 4:
Exact information on specifications is not possible as the display is largely dependent on the ambient temperature.
Evaluating display group 3, display zone 4 - Intake air temperature
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Appears on display
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Possible fault cause
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Fault elimination
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Constant 46.5 °C
or 141.0 °C
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- Fault on intake manifold temperature sender -G72 recognised
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- Interrogate fault memory => Page 01-12
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- Intake manifold temperature sender -G72
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- Check intake manifold temperature sender -G72
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