Volkswagen Workshop Service and Repair Manuals

Notes:

• ◆ The idling check is performed in the basic setting function of the fault reader V.A.G 1551.
• ◆ In the basic setting, the Digifant control unit is matched to the throttle valve potentiometer at idling speed. Idling speed stabilization, Lambda control and ignition timing adjustment are switched off.
• ◆ Observe test sequence.

• ● Engine oil temperature min. 80 °C
• ● Electrical consumers switched off (radiator fan must not run during the check/adjustment).

• ● Air conditioner switched off
• ● Accelerator cable adjustment OK

=> Repair group 20; Removing and installing parts of fuel supply system; Adjusting throttle cable

• ● Exhaust system must be free of leaks

• ‒ → Connect ignition tester V.A.G 1367 with pick-up clamp V.A.G 1367/8 or ignition tester V.A.G 1767.
• ‒ → Connect CO tester V.A.G 1363A with adapter V.A.G 1363/3 to CO sampling pipe.

• ‒ → Pull off crankcase breather hose at pressure regulating valve and seal hose opening to intake hose -arrow-.
• ‒ Interrogate and erase fault memory, eliminate faults if necessary .
• ‒ Operate fault reader taking into account the information on the display:
• ‒ Press ⇒ button.
• ‒ Input 04 for "Initiate basic setting" and confirm with Q.

• ‒ Input 01 for display group 01 and confirm with Q.

Do not continue with check until 00000000 appears in the 4th display zone.

Note:

If one or more 1s appear in display zone 4, test conditions are not satisfied:

=>Meaning of figures in display zone 4,

Page 24-30 .

• ‒ Checking ignition timing at 2000...2500 rpm.
       Specification: 4...8° before TDC1)
• ‒ If necessary adjust ignition timing by turning the distributor:
       Setting figure: 6 ± 1° before TDC1)

     1)     Up-to-date specifications:

=> "Emission and idling test" binder

• ‒ Allow engine to idle for at least 1 minute.

• ‒ → Check idling speed and CO content, if necessary adjust by alternately turning CO adjustment screw -A- and idling speed adjustment screw -B-.
       Idling speed: 800 ±50 rpm1)
       CO content 0.7 ±0.4 Vol. %1)

• Workshops above 300 m altitude add 0.2 Vol.% for every additional 100 m.

     1)     Up-to-date specifications:

=> "Emission and idling test" binder

• ‒ After adjusting CO adjustment screw, seal with an anti-tamper plug.
• ‒ Allow engine to idle for at least 1 minute.
• ‒ End the engine basic setting by pressing the⇒ button. When doing this the radiator fan must not run.

Note:

After completing basic setting, CO content lies within the range 0.3...1.1 % volume, even at attitudes above 300 m.

• ‒ Reconnect crankcase breather hose.
• ‒ Input 08 for "Read measured value block" function and confirm with Q.

• ‒ Input 01 for display group 01 and confirm with Q.

• ‒ Increase engine speed to approx. 2500 rpm for 1 minute and then allow engine to idle.
• ‒ Read Lambda voltage in display zone 3. Lambda voltage must fluctuate by
       more than 0.3 V.
  

If Lambda voltage does not fluctuate:

• ‒ Check Lambda probe and Lambda control
  => Page 24-32
• ‒ Press ⇒ key.
• ‒ Input 06 for "End output" and confirm with Q.

Meaning of numbers in display zone 4

The control unit is only in check or adjust mode if 00000000 appears in the 4th display zone (conditions satisfied). The conditions are not satisfied if one or more 1s appear in display zone 4:

• ◆ 01000000 = Signal from automatic gearbox control unit to Digifant control unit not OK.
• ◆ 00100000 = Air conditioner not switched off
• ◆ 00000100 = Throttle valve not closed
• ◆ 00000010 = Engine speed outside permitted range
• ◆ 00000001 = Coolant temperature below 85 °C