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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 catalytic converter
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110
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Lambda regulation status before catalytic converter
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111
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=> Page 01-126
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Note on display zone 2:
The 3rd character in the display is not set to 1 (Lambda regulation active) until the engine is run in the part throttle range.
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 catalytic converter1)
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-10.0...10.0 %
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=> Page 01-129
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Lambda learnt value at idling speed (additive) before catalytic converter
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-10.0...10.0 %
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=> Page 01-129
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1) Readings will only be displayed after driving for some time at part throttle and reducing engine rpm to idling speed several times.
Note:
"Multiplicative" means that the fault will have an effect across the whole range of engine speeds and engine loads.
"Additive" means that the fault will only have an effect at idling speed.
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 24-88
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- Activated charcoal filter solenoid valve 1 permanently open
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- Check activated charcoal filter solenoid valve 1 => Page 01-72, Final control diagnosis
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- Lambda probe heating defective or Lambda probe soiled
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- Check Lambda probe heating before catalytic converter
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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 24-88
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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 catalytic converter
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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 catalytic converter
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0.4...0.5 V
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---
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Lambda regulator before catalytic converter
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-15.0...15.0 %
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=> Page 01-132
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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 01-19.
Evaluating display group 33, display zone 1 - Lambda regulator before catalytic converter
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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 24-93
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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 catalytic converter (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 catalytic converter 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 catalytic converter
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max. 1.0 s
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---
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Catalytic converter 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 catalytic converter
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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 catalytic converter (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 catalytic converter
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0.000...1.000 V
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=> Page 01-135
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Evaluating display group 36, display zone 1 - Lambda probe voltage, Lambda probe after catalytic converter
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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 24-107
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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 catalytic converter
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0.000...1.000 V
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=> Page 01-135
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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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◂ 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 catalytic converter
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Htg.aC.ON
Htg.aC.OFF
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Lambda probe heating resistance after catalytic converter
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Lambda probe heating before catalytic converter
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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- Catalytic converter 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 catalytic converter conversion test
(Test OFF / test ON / Cat B1 OK/Cat B1 n.OK)
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Cat B1 OK
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---
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Catalytic converter conversion measurement
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at least 50 %
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Catalytic converter 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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◆ Conditions required for the conversion test:
No entries in fault memory, engine running at increased rpm, coolant temperature 60...118 °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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---
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Lambda regulator before catalytic converter
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-15.0...15.0 %
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=> Page 01-132
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Coolant temperature
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80...110 °C
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=> Page 01-108
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Engine speed (idling speed)
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630...830 rpm1)
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=> Page 01-100
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1) Up-to-date specifications:
=> Exhaust emissions test binder
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