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Evaluating measured value blocks, display groups 50...69 -Speed regulation- > < Evaluating measured value blocks, display groups 10...29 -Ignition-
Motronic injection and ignition system (1.8 l engine)
Evaluating measured value blocks, display groups 30...49, 99, 107 -Lambda regulation-
Evaluating measured value blocks, display groups 30...49, 99, 107 -Lambda regulation-

Display group 30 -Lambda regulation-

▪ Engine running at idling speed

Read measured value block 30

◂ Indicated on display

xxx

xxx

1

2

3

4

◂ Display zones

Specification

Evaluation

Lambda regulation status after catalyst

110

Lambda regulation status before catalyst

111

=> Page 01-126

Significance of 3 digit number block in display zones 1 and 2

Significance if display = 1

1

2

3

1

Lambda regulation active

1

Lambda probe operationally ready

1

Lambda probe heating on

Display group 32 -Lambda regulation- Lambda learnt values

▪ Engine running at idling speed

Read measured value block 32

◂ Indicated on display

xx.x %

xx.x %

1

2

3

4

◂ Display zones

Specification

Evaluation

Lambda learnt value at part load (range 2)

-19.0...19.0 %

=> Page 01-128

Lambda learnt value at idling speed (range 1)

-8.0...8.0 %

=> Page 01-128

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.

  • ◆ High values indicate that the engine is running too lean and therefore the Lambda regulation enriches the mixture.
  • ◆ If there is no voltage supply to the control unit and the fault memory is erased, all the values learnt will be cancelled.
  • ◆ Range 1 - The effects of the fault (e.g. unmetered air) decrease as the engine speed increases. The injection period is modified by a fixed amount by this learnt value. This amount is not dependent upon the basic injection period.
  • ◆ Range 2 - The effects of the fault (e.g. faulty injector) increase as the engine speed increases. This learnt value effects the injection period proportionally. This change is dependent on the basic injection period.

Initiating learning process: Control unit in mode 04, Basic settings

  • ◆ Learning conditions for idling: Idling, coolant temperature min. 75 °C, intake air temperature max. 90 °C
  • ◆ Learning conditions for part load: coolant temperature min. 75 °C, intake air temperature max. 90 °C

Evaluating display zone 32, display zones 1 and 2 - Lambda learnt values

Appears on display

Possible fault cause

Fault elimination

Low Lambda learnt values

- Low learnt values at idling but with normal learnt values at part throttle: possible oil dilution (high level of fuel in oil)

- Disappears after motorway drive or oil change

- Injector leaking

- Check injector

- Fuel pressure too high

- Check fuel pressure regulator and holding pressure => Page 24-70

- Activated charcoal filter solenoid valve 1 permanently open

- Check activated charcoal filter solenoid valve 1 => Page 01-88, Final control diagnosis

- Air mass meter defective

- Check air mass meter => Page 24-33

- Lambda probe heating defective or Lambda probe soiled

- Check Lambda probe heating

Appears on display

Possible fault cause

Fault elimination

High Lambda learnt values

- High learnt values at idling speed, not so high learnt values at part throttle: possible unmetered air in area of intake manifold

- Check intake air system for leaks

- Unmetered air between air mass meter and throttle valve

- Rectify cause

- Injector blocked

- Check quantity injected rate

- Display zones 1 and 2 high: Air mass meter defective

- Check air mass meter => Page 24-33

- Fuel pressure too low

- Check fuel pressure regulator and holding pressure => Page 24-70

- Unmetered air at exhaust manifold gasket

- Lambda probe heating defective or Lambda probe soiled

- Check Lambda probe heating

Display group 33 -Lambda regulation- Lambda regulation values

▪ Engine running at idling speed

Read measured value block 33

◂ Indicated on display

xx.x %

x.xxx V

1

2

3

4

◂ Display zones

Specification

Evaluation

Lambda probe voltage, Lambda probe before catalyst

0.000...5.000 V

---

Lambda regulator before catalyst

-25.0...25.0 %

=> Page 01-131

Notes on display zone 1:

  • ◆ 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 01-18.

Evaluating display group 33, display zone 1 - Lambda regulator before catalyst

Appears on display

Possible fault cause

Fault elimination

Outside tolerance range

- Minus range: Mixture too rich, Lambda control weakens mixture
- Positive range: Mixture too lean, Lambda control enriches mixture

- Wait 30 seconds until the display has stabilised

- Unmetered air

- Check intake system for leaks
=> Page 24-76

- Injector defective

- Check injection rate => Page 24-60

- Lambda learnt value on limit

- Check Lambda learnt value in display group 32

Display group 34 -Lambda regulation- Lambda probe diagnosis before catalyst (ageing check)

▪ Vehicle stationary, engine running at increased idling speed

▪ Control unit in mode 04-Basic settings

Read measured value block 34

◂ Indicated on display

xxxx rpm

xxx.x °C

xx.xx

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Result of Lambda probe before catalyst age check (test OFF/test ON/B1-P1 OK / B1-P1 n.OK)


B1-P1 OK


---

Dynamics factor of Lambda probe before catalyst


0.00...1.99


---

Exhaust gas/catalyst temperature

min. 300 °C

---

Engine speed

1 800...2 200 rpm

---

Note on display zone 2:

Value calculated from engine speed and engine load.

Note on display zone 3 and 4:

The dynamics factor is a measure of the ageing condition of the Lambda probe. If this value is exceeded, "B1-P1 n. OK" will appear in display zone 4.

Display group 36 -Lambda regulation- Operational readiness of probe after catalyst

▪ Vehicle stationary, engine running at high idling speed at 1 800...2 800 rpm

▪ Control unit in mode 04-Basic settings

Read measured value block 36

◂ Indicated on display

x.xxx V

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Lambda probe after catalyst test (Test OFF/Test ON/B1-P2 OK/ B1-P2 n.OK)


B1-P2 OK


---

Lambda probe voltage, Lambda probe after catalyst

0.100...0.900 V

=> Page 01-134

Evaluating display group 36, display zone 1 - Lambda probe voltage,Lambda probe after catalyst

Appears on display

Possible fault cause

Fault elimination

Constant 1.100 V

- Short to positive via:
- Lambda probe, probe wiring, earth wiring, engine control unit

- Check Lambda probe wiring
=> Page 24-93

Constant between
0.400...0.500 V

- Open circuit via:
- Lambda probe, probe wiring, earth wiring, engine control unit

Constant 0.000 V

- Short to earth via:
- Lambda probe, probe wiring, earth wiring, engine control unit

Display group 37 -Lambda regulation-

▪ Vehicle stationary, engine running at high idling speed at 1 800...2 800 rpm

▪ Control unit in mode 04-Basic settings

Read measured value block 37

◂ Indicated on display

xx.x %

x.xxx V

x.xxx

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Result (Test On / OFF /
Syst. OK / n.OK)


Syst. OK

Delta, Lambda after catalyst

-0.5...0.5

Lambda probe voltage, Lambda probe after catalyst


0.100...0.900 V

=> Page 01-134

Engine load

10...25 %

=> Page 01-120

Display group 41 -Lambda regulation- Lambda probe heating

▪ Engine running at idling speed

Read measured value block 41

◂ Indicated on display

x.x kOhm

Text

x.x kOhm

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Lambda probe heating after catalyst

Htg.aC.ON
Htg.aC.OFF

---

Resistance, Lambda probe heating before catalyst

---

---

Lambda probe heating before catalyst

Htg.bC.ON
Htg.bC.OFF

---

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".

Display group 43 -Lambda regulation- Lambda probe diagnosis before catalyst (ageing check)

▪ Vehicle stationary, engine running at increased idling speed

▪ Control unit in mode 04-Basic settings

Read measured value block 43

◂ Indicated on display

xxxx rpm

xxx.x °C

x.xxx s

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Result of ageing check of Lambda probe after catalyst (test OFF/test ON/B1-P2 OK / B1-P2 n.OK)


B1-P1 OK


---

Lambda probe voltage, Lambda probe after catalyst


0.100...0.900 V


---

Exhaust gas/catalyst temperature

min. 350 °C

---

Engine speed

1 800...2 200 rpm

---

Note on display zone 2:

Value calculated from engine speed and engine load.

Display group 99 -Lambda regulation- Lambda regulation operating condition

▪ Engine running at idling speed

▪ Control unit in mode 04-Basic setting, Lambda regulation off

▪ Control unit in mode 08-Read measured value block, Lambda regulation on

Read measured value block 99

◂ Indicated on display

xxxx rpm

xx.x °C

x.x %

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Lambda regulation operating mode

λ-Reg. OFF or
λ-Reg. ON

---

Lambda regulator before catalyst

-25.0...25.0 %

=> Page 01-131

Coolant temperature

80...110 °C

=> Page 01-115

Engine speed (idling speed):

760...880 rpm

=> Page 01-109

Notes on display zone 4:

  • ◆ 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.
  • ◆ 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.

Display group 107 -Lambda regulation- Lambda regulation diagnosis

▪ Engine running at idling speed

▪ Control unit in mode 04-Basic settings

Read measured value block 107

◂ Indicated on display

xxxx rpm

x.x %

Text

1

2

3

4

◂ Display zones

Specification

Evaluation

Result of diagnosis (Test OFF/Test ON / Syst. OK / Syst. n.OK))


Syst. OK


---

Lambda regulation (averaged value)

-25.0...25.0 %

---

Engine speed (idling speed):

760...880 rpm

=> Page 01-109

Notes on display zone 4:

Evaluation of Lambda learnt values in display group 32:

  • ◆ At idling speed (range 1) +/- 8 %. If outside specified range, then Syst. n.OK.
  • ◆ At partial load (range 2) +/- 19 %. If outside specified range, then Syst. n.OK.

Evaluating measured value blocks, display groups 50...69 -Speed regulation- > < Evaluating measured value blocks, display groups 10...29 -Ignition-