Engine Operating Mode, Checking

NOTES: Checks whether engine control unit recognizes the engine operating modes idling, overrun, part throttle, enrichment, full throttle.


Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG1551 scan tool or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3

Test conditions
- Coolant temperature must be at least 80 °C, See display group 04, display zone 3.

Test sequence
- Connect VAG1551 scan tool (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 scan tool and selecting engine control unit.) Testing and Inspection

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
Input display group number XXX

- Press keys 0, 0 and 5 for "Display group number 5" and confirm entry with Q key.

Indicated on display: (1-4 = Display zones)

Read measured value block 5 ->
1 2 3 4

- Check whether the control unit recognizes the operating mode (display zone 4):
- Idling:

- As long as the engine is running at idling speed idling must be displayed Display:Idling
- Overrun mode:
- Increase engine speed to above 3000 rpm.
- Close throttle abruptly.
- As long as the engine speed is above 1400 rpm overrun must be displayed Display:Overrun

NOTES: Below 1400 rpm idling speed will be recognized.

- Part throttle:

- Rev up evenly.
- As long as the engine is being revved up evenly, part throttle must be displayed Display: Part throttle
- Enrichment:
- Floor accelerator pedal (onto throttle valve stop).
- Acceleration enrichment must be displayed briefly
- Display: Enrichment

Observe the valid safety precautions when carrying out a road test. Technician Safety Information

- Press -> key.
- Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

It the specifications are not attained:
- Check DTC memory, if necessary, repair any faults and then erase DTC memory. Testing and Inspection
- Check throttle valve control module. Testing and Inspection