volkswagen Workshop Repair Guides

Volkswagen Workshop Service and Repair Manuals

Checking intake air preheating > < Checking fuel pressure regulator and holding pressure
Motronic fuel injection and ignition system 08.95 ä
Motronic injection and ignition system
Checking intake air system for leaks (unmetered air)

Checking with engine leak detector spray G 001 800 A1

Special tools, testers and auxiliary items

  • ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
  • ◆ 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 outside air. The leak detector spray reduces the ignitability of the mixture. This leads to a drop in engine speed and to a significant increase of the CO content.
  • ◆ The safety precautions listed on the container must be adhered to.

Test sequence

  • ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
    (Connecting fault reader and selecting engine electronics control unit .)
 
→ Indicated on display:
Rapid data transfer     HELP
Select function XX
  • ‒ 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     HELP
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
  • ‒ Note Lambda control in display zone 3.

Display zones

1

2

3

4

Display group 1: Idling test

Display

xxxx rpm

xxx.x °C

xx.x%

xx.x <°

Indicated

Engine speed

Engine temperature

Lambda control

Ignition angle

Working range

800...6000 rpm

---

-25.0...25.0 %

0.0...40.0 <°

Specification

800...880 rpm

---

The value must fluctuate at least 2 % in range -5.0...5.0 %

2.0...15.0 <°

  • ‒ Systematically spray parts of the intake system with engine leak detector spray.

If the engine speed drops or the figure displayed for Lambda control changes:

  • ‒ Check the area of the intake system which has been sprayed for leaks and eliminate leaks.

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