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Evaluating measured value blocks, display grps 30...49, 99 -Lambda regulation-
Evaluating measured value blocks, display grps 30...49, 99 -Lambda regulation-
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Display group 30 -Lambda regulation-
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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 regulation status after catalyst
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110
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Lambda regulation status before catalyst
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111
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=> Page 01-115
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Note on display zone 2:
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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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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---
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---
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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 learnt value at part load (multiplicative) before catalyst
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-10.0...10.0 %
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=> Page 01-118
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Lambda learnt value at idling speed (additive) before catalyst
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-10.0...10.0 %
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=> Page 01-118
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Notes on display zones 1 and 2:
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.
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◆ Learning conditions for part load: coolant temperature min. 75 °C, intake air temperature max. 90 °C, whilst driving.
Evaluating display zone 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 24-81
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- Activated charcoal filter solenoid valve 1 permanently open
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- Check activated charcoal filter solenoid valve 1 => Page , Final control diagnosis
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- Lambda probe heating defective or Lambda probe soiled
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- Check Lambda probe heating before 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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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 filter and throttle valve
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- Eliminate cause
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- Injector blocked
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- Check quantity injected rate
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- Fuel pressure too low
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- Check fuel pressure regulator and holding pressure => Page 24-81
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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 before catalyst
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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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---
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---
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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 voltage, Lambda probe before catalyst
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0.000...1.000 V
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---
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Lambda regulator before catalyst
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-10.0...10.0 %
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=> Page 01-121
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Notes on display zone 1:
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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 01-16
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Evaluating display group 33, display zone 1 - Lambda regulator before 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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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 24-85
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- Injector defective
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- Check injectors
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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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Display group 34 -Lambda regulation- Lambda probe diagnosis before catalyst (checking ageing via amplitude duration monitoring)
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- Rev up briefly over 5,000 rpm twice
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▪ Vehicle stationary, engine running at raised speed
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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.xx s
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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 ageing 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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Cycle duration Lambda probe before catalyst
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max. 1.0 s
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Catalyst temperature
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---
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---
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Engine speed
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1500...3900 rpm
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Note on display zone 3 and 4:
The cycle duration of the lambda probe indicates the time between two voltage pulses (e.g. rich - lean - rich). It is therefore a means of evaluating lambda probe ageing (i.e. the condition of the lambda probe). If the indicated cycle duration is exceeded, "B1-P1 n. OK" will appear in display zone 4.
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Display group 36 -Lambda regulation- Operational readiness of probe after catalyst
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▪ Vehicle stationary, foot brake depressed, engine running at increased idling speed (1500...4000 rpm)
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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 after catalyst
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0.000...1.000 V
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=> Page 01-124
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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 2 basic voltage
=> Page 24-99
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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 37 -Lambda regulation- Lambda probes
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▪ Whilst driving
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Read measured value block 37
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◂ Indicated on display
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xxx %
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x.xxx V
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xxx.xxx
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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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Test of Lambda probes
(Test ON / OFF / Syst. OK / n.OK)
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Syst. OK
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Not for Service
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Lambda probe voltage
Lambda probe after catalyst
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0.000...1.000 V
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=> Page 01-124
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Engine load
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12.0...40.0 %
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Display group 41 -Lambda regulation- Lambda probe heating
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▪ Engine running at idling speed
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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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xxx ω
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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 after catalyst
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Htg.aC.ON
Htg.aC.OFF
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Lambda probe heating resistance after catalyst
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Lambda probe heating before catalyst
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Htg.bC.ON
Htg.bC.OFF
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Note:
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 46 -Lambda regulation- Catalyst diagnosis (conversion test)
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▪ Control unit in mode 04-Basic setting
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▪ Vehicle stationary, engine running at raised speed
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Read measured value block 46
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◂ Indicated on display
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xxxx rpm
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xxxx °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 catalyst conversion test
(Test OFF / test ON / Cat B1 OK/Cat B1 n.OK)
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Cat B1 OK
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Catalyst conversion measurement
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at least 50 %
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Catalyst temperature
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at least 300 °C
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Engine speed
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1500...3900 rpm,
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Note to display group 46:
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◆ Prerequisite for the conversion check:
No entries in fault memory, engine running at idling speed, coolant temperature 60...120 °C, Lambda regulation active and stable.
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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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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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xxx.x °C
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xx.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 before catalyst
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-10.0...10.0 %
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=> Page 01-121
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Coolant temperature
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80...110 °C
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=> Page 01-98
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Engine speed (idling speed)
Vehicles with engine code AUA
Vehicles with engine code AUB
Vehicles with automatic gearbox
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800...900 rpm1)
790...890 rpm1)
630...730 rpm1)
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=> Page 01-90
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1)
Up-to-date specifications:
=> Exhaust emissions test binder
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