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Evaluating measured value blocks, display grps. 30...33, 99 -Lambda regulation-
Evaluating measured value blocks, display grps. 30...33, 99 -Lambda regulation-
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Display group 30 -Lambda regulation status-
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▪ Engine running at idling speed
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Read measured value block 30
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◂ Indicated on display
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xxx
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xxx
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Lambda probe status, probe 2 bank 1 after catalyst
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111
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Lambda probe status, probe 1 bank 1 after catalyst
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111
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=> Page 01-145
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Note on display zone 2:
The third display position is not set to "1" until the partial-load range is reached.
Significance of 3 digit number block in display zone 1:
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Significance if display = 1
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1
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2
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3
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1
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Lambda regulation active
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1
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Lambda probe operationally ready
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1
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Lambda probe heating on
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Note:
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◆ Depending on the status of the Lambda regulation, 0 or 1 may appear alternately in the 3-digit block, but the Lambda probe must always be operationally ready.
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◆ The 1 set for the Lambda probe heating may sporadically be 0 because the heating is pulsed.
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Display group 32 -Lambda regulation- Lambda learnt values
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▪ Engine running at idling speed
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Read measured value block 32
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◂ Indicated on display
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xx.x %
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xx.x %
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Probe 1 bank 1 Lambda learnt value at partial load (mul.)
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-10...10 %
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=> Page 01-147
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Probe 1 bank 1 Lambda learnt value at idle (add.)
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-5.4...5.4 %
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=> Page 01-147
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Notes on display zones 1 and 2:
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◆ The operating range of the Lambda regulation lies between -25...25 %.
Low values indicate that the engine is running too rich and therefore the Lambda regulation is leaning the mixture.
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◆ High values indicate that the engine is running too lean and therefore the Lambda regulation enriches the mixture.
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◆ If there is no voltage supply to the control unit all the values learnt will be cancelled.
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◆ add = additive - The effects of the fault (e.g. unmetered air) will reduce as the engine speed increases. The injection period will be modified by a fixed amount for additive learnt values. This amount is not dependent upon the basic injection period.
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◆ mul = multiplicative - The effects of the fault (e.g. faulty injector) will increase as the engine speed increases. A multiplicative learnt value is a proportional change to the injection period. This change is dependent on the basic injection period.
Initiating learning process: Control unit in mode 04, Basic settings
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◆ Learning conditions for idling: Idling, coolant temperature min. 70 °C, intake air temperature max. 80 °C
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◆ Learning conditions for partial load: coolant temperature min. 70 °C, intake air temperature max. 80 °C
Evaluating display group 32, display zones 1 and 2 - Lambda learnt values
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Appears on display
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Possible fault cause
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Fault elimination
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Low Lambda learnt values
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- Low learnt values at idling but with normal learnt values at part throttle: possible oil dilution (high level of fuel in oil)
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- Disappears after motorway drive or oil change
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- Injector leaking
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- Check injector
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- Fuel pressure too high
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- Check fuel pressure regulator and holding pressure => Page 24-101
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- Activated charcoal filter solenoid valve 1 permanently open
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- Check activated charcoal filter solenoid valve 1 => Page 01-89, Final control diagnosis
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- Air mass meter defective
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- Check air mass meter => Page 24-49
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- Lambda probe heating defective or Lambda probe soiled
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- Check Lambda probe heating
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Continuation on next page
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Appears on display
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Possible fault cause
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Fault elimination
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High Lambda learnt values
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- High learnt values at idling speed, not so high learnt values at part throttle: possible unmetered air in area of intake manifold
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- Check intake air system for leaks
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- Unmetered air between air mass meter and throttle valve
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- Rectify cause
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- Injector blocked
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- Check quantity injected rate
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- Display zones 1 and 2 high: Air mass meter defective
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- Check air mass meter => Page 24-49
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- Fuel pressure too low
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- Check fuel pressure regulator and holding pressure => Page 24-101
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- Activated charcoal filter solenoid valve 1 permanently open
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- Check activated charcoal filter solenoid valve 1 => Page 01-89, Final control diagnosis
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- Unmetered air at exhaust manifold gasket
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- Lambda probe heating defective or Lambda probe soiled
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- Check Lambda probe heating
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Display group 33 -Lambda regulation- Lambda regulation values
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▪ Engine running at idling speed
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Read measured value block 33
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◂ Indicated on display
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xx.x %
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x.xxx V
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Probe voltage Lambda probe 1 bank 1
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1.400...1.600 V
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=> Page 01-150
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Lambda regulation Bank 1
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-10.0...10.0 %
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=>Page01-150
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Notes on display zone 1:
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◆ The display must at least fluctuate around 0 %. If 0 is constantly displayed, the Lambda regulator has switched from regulation to control because a fault has occurred in the Lambda regulation. Interrogate fault memory => Page 01-16.
Evaluating display group 33, display zone 1 - Lambda regulator, bank 1
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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 enriches 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 24-108
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- Injector defective
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- Check injection rate => Page 24-89
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- Lambda learnt value on limit
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- Check Lambda learnt value in display group 32
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Evaluating display group 33, display zone 2 - Lambda probe voltage, bank 1
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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 1.5 V
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- Wiring open circuit
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- Check Lambda probe wiring
=> Pages 24-125
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Display group 34 -Lambda regulation- Lambda probe diagnosis before catalyst (checking age)
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▪ Vehicle stationary, engine running at fast idle (only with depressed brake and accelerator in wide-open position)
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▪ Control unit in mode 04-Basic settings
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Read measured value block 34
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◂ Indicated on display
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xxxx rpm
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xxx.x °C
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xx
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Text
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Result of Lambda probe before catalyst age check (test OFF/test ON/B1-P1 OK / B1-P1 n.OK)
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B1-P1 OK
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---
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Dynamic factor of Lambda probe before catalyst
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0.5...2
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Catalyst temperature
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min. 350 °C
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Engine speed
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ca. 2 300 rpm
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Note on display zone 2:
Value calculated from engine speed and engine load.
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Display group 36 -Lambda regulation- Operational readiness of probe after catalyst
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▪ Engine running at idling speed
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▪ Control unit in mode 04-Basic settings
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Read measured value block 36
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◂ Indicated on display
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x.xxx V
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Text
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Check Lambda probe after catalyst (Test OFF/Test ON/B1-P2 OK / B1-P2 n.OK)
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B1-P2 OK
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Lambda probe voltage, Lambda probe after catalyst
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0.100...0.900 V
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=> Page 01-153
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Evaluating display group 36, display zone 1 - Lambda probe voltage,Lambda probe after catalyst
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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 1.100 V
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- Short to positive via:
- Lambda probe, probe wiring, earth wiring, engine control unit
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- Check Lambda probe wiring
=> Page 24-127
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Constant between
0.400...0.500 V
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- Open circuit via:
- Lambda probe, probe wiring, earth wiring, engine control unit
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Constant 0.000 V
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- Short to earth via:
- Lambda probe, probe wiring, earth wiring, engine control unit
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Display group 41 -Lambda probe heating before and after catalyst, bank 1-
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▪ Vehicle standing, engine idling
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Read measured value block 41
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⇒
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◂ Indicated on display
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Text
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Text
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Lambda probe heating probe 2 bank 1 (after catalyst)
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Htg.aC. ON
Htg.aC. OFF
sporadically changing
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Lambda probe heating after catalyst, resistance
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0...25 kOhm
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Lambda probe heating probe 1 bank 1
(before catalyst)
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Htg.bC. ON
Htg.bC. OFF
sporadically changing
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Note on display zones 2 and 4:
The Lambda probe heating may be switched ON or OFF depending on the operating conditions of the engine, therefore the display in display zone 2 or 4 may show "Htg.b(a)C.ON" or alternating from "Htg.b(a)C.ON" to Htg.b(a)C.OFF".
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Display group 43 -Lambda regulation- Lambda probe after catalyst diagnosis (ageing test)
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▪ Vehicle stationary, engine running at fast idle (only with depressed brake and accelerator in wide-open position)
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▪ Control unit in mode 04-Basic settings
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Read measured value block 43
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⇒
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◂ Indicated on display
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xxxx/min
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xxx.x °C
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x.xx V
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Text
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Result of Lambda probe after catalyst ageing test (Test OFF/Test ON/B1-P2 OK / B1-P2 n.OK
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B1-P2 OK
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---
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Probe voltage Lambda probe 2 bank 1
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0.00...1.00 V
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Catalyst temperature
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min. 350 °C
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Engine speed
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ca. 2 300 rpm
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Note on display zone 2:
Value calculated from engine speed and engine load.
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Display group 99 -Lambda regulation- Lambda regulation operating condition
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▪ Engine running at idling speed
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▪ Control unit in mode 04-Basic setting, Lambda regulation off
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▪ Control unit in mode 08-Read measured value block, Lambda regulation on
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Read measured value block 99
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⇒
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◂ Indicated on display
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xxxx rpm
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xx.x °C
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x.x %
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Text
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Lambda regulation operating mode
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λ-Reg. OFF or
λ-Reg. ON
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Lambda regulator
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-10.0...10.0 %
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=> Page 01-150
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Coolant temperature
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80...110 °C
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=> Page 01-131
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-125
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Notes on display zone 4:
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◆ For a defined fault finding the Lambda regulation is switched off when selecting display group 99 under "Basic setting" or switched on under "Read measured value block".
When the function 04 "Basic setting" is exited the Lambda regulation is automatically active again.
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◆ It is possible to switch between the function 04 "Basic setting" and the function 08 "Read measured value block" by pressing the keys 4 and 8 on V.A.G 1551/1552.
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