volkswagen Workshop Repair Guides

Volkswagen Workshop Service and Repair Manuals

Checking intake air preheating > < Checking fuel pressure regulator and holding pressure
Motronic inj. and ignition system (2-valve, roller rocker finger)
Checking components
Checking intake air system for leaks (unmetered air)

Checking with engine leak detector spray G 001 800 A1

Notes:

  • ◆ The vacuum in the intake system will cause the leak detector spray to be drawn in with the unmetered air. The leak detector spray reduces the ignitability of the mixture. This leads to a drop in engine speed and to a change of Lambda probe reading.
  • ◆ The safety precautions listed on the container must be adhered to.

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

  • ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3A
  • ◆ Engine leak detector spray G 001 800 A1

Test conditions

  • ● Coolant temperature must be at least 80 °C, =>display group 04, display zone 3.

Test sequence

  • ‒ Remove air cleaner , Fig. 3 .
  • ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
    (Connecting fault reader and selecting engine control unit => Page 01-9 .)
 
→ Indicated on display:
Rapid data transfer     HELP
Select function XXX
  • ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.
 
→ Indicated on display:
Read measured value block
Input display group number XXX
  • ‒ Press keys 0, 0 and 1 for "Display group number 1" and confirm entry with Q key.
 
→ Indicated on display:
(1...4 = Display zones)
Read measured value block     1     ⇒
     1     2     3     4

Only continue with the test when

  • ● The coolant temperature exceeds 80 °C
    -display zone 2-
  • ‒ Observe the engine speed in display zone 1 and the Lambda regulation in display zone 3.
  • ‒ Systematically spray parts of the intake system with engine leak detector spray.

If the engine speed drops or the Lambda regulator changes:

  • ‒ Press ⇒key.
  • ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
  • ‒ Switch off ignition.
  • ‒ Check sprayed areas of intake system for leaks and rectify if necessary.

If the engine speed or Lambda regulator does not change:

  • ‒ Press ⇒key.
  • ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
  • ‒ Switch off ignition.

Checking intake air preheating > < Checking fuel pressure regulator and holding pressure