Volkswagen Polo Workshop Service and Repair Manuals

Note:

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

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

Check conditions

• ● Coolant temperature must be at least 80 °C, =>display group 1, display zone 2.
• ● Throttle cable adjustment must be OK, checking:

=> Repair group 20; Throttle controls; Adjusting throttle cable

Test sequence

• ‒ 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 .)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 1 for "Display group number 1" and confirm entry with Q key.

• ‒ Check whether the coolant temperature is above 80 °C in display zone 2.
• ‒ Press C key.

• ‒ Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

• ‒ Observe -8 digit number block- in display zone 4 :
  (The right-hand 4 digits are of no consequence)

Display in operating mode

• ◆ Idling:

• With throttle valve closed, 2nd position from left must display 1
       Display: 01000000

• ◆ Part throttle:

• ‒ Rev up evenly.

• 3rd position from left must display 1
       Display: 00100000

• ◆ Full throttle:

• ‒ Briefly open throttle fully (throttle burst).

• 4th position from left must briefly display 1
       Display: 00010000

Note:

A test drive may have to be performed to show "Full throttle" in display.

A 2nd person is required when performing a test drive.

Observe the valid safety measures during a test drive => Page 24-28 .

• ◆ Overrun mode:

• ‒ Increase engine speed to above 3000 rpm.
• ‒ Close throttle valve abruptly.

• As long as the engine speed is above 1400 rpm, 1st position from left must display 1
       Display: 11000000 (briefly)

Note:

Below 1400 rpm idling speed is again recognised.

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

If the specifications are not attained:

• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-13 , interrogating and erasing fault memory.
• ‒ Check accelerator mechanism for ease of operation.
• ‒ Check throttle valve potentiometer
  => Page 24-35 , Checking throttle valve control part.