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Volkswagen Workshop Service and Repair Manuals

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Checking throttle valve potentiometer > < Checking Lambda probe and Lambda control

Golf Mk3

Motronic injection and ignition system (4-Cyl. engine)
Motronic injection and ignition system
Checking engine operation

Note:

Check establishes whether Motronic control unit (J220) recognises the engine operating condition.

Special tools, testers and auxiliary items

  • ◆ Fault reader V.A.G 1551 with cable V.A.G 1551/3

Test sequence

  • ‒ Start engine and run at idling speed.
  • ‒ Connect fault reader V.A.G 1551 and select engine electronics control unit (address word 01); selection is carried out with engine idling .
 
→ Indicated on display:
Rapid data transmission     HELP
Select function XX
  • ‒ Input 08 for "Read measuring value block" function and confirm with Q.
 
→ Indicated on display:
Reading measuring value block     HELP
Input display group number XX
  • ‒ Input 04 for display group 04 and confirm with Q.
 
→ Indicated on display:
(1...4 = Display zones)
Read measuring value block 4     ⇒
     1     2     3     4

Note:

If something different is indicated on the display:

=> Fault reader operating instructions

Idling speed:
     
    → Observe 4th position from left in display zone 4.
         Specification: 1
    Read measuring value block 4     ⇒
         ...rpm     ...%     ...km/h     00010

    Part-load:
       
      → Observe 3rd position from left in display zone 4 and smoothly open throttle.
           Specification: 1
      Read measuring value block 4     ⇒
           ...rpm     ...%     ...km/h     00100

      Full throttle:
         
        → Observe 2nd position from left in display zone 4 and open throttle fully (rev up).
             Specification: 1
        Read measuring value block 4     ⇒
             ...rpm     ...%     ...km/h     01000

        Acceleration enrichment:
           
          → Observe 1st position from left in display zone 4 and open throttle fully (rev up to over 3000 rpm, coolant temperature below 70 °C).
               Specification: 1
          Read measuring value block 4     ⇒
               ...rpm     ...%     ...km/h     10000

          Overrun:

          • ‒ Increase engine speed to above 3000 rpm.
          • ‒ Observe 5th position from left in display zone 4.
           
          → Close throttle valve abruptly.
               Specification: above 1200 rpm = 1
          Read measuring value block 4     ⇒
               ...rpm     ...%     ...km/h     00001

          Note:

          Below 1200 rpm idling speed will be recognised.

          • ‒ Press ⇒ button.
          • ‒ Input 06 for "End output" and confirm with Q.

          If the specifications are not attained:

          • ‒ Interrogate and erase fault memory, eliminate faults if necessary => Page 01-5 .
          • ‒ Check accelerator mechanism for ease of operation.
          • ‒ Check throttle valve potentiometer
            => Page 24-34 .

          Checking throttle valve potentiometer > < Checking Lambda probe and Lambda control