Knock control, checking

Connect VAG1551 or VAG1552 Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (engine running at idle). See VAG1551 OR VAG1552 SCAN TOOL (ST), CONNECTING AND SELECTING "ENGINE ELECTRONICS" ADDRESS WORD 01 .

Indicated on display

Fig 1: VAG1551 Tool Display - Knock Control (1 Of 3)

Press buttons -0- and -8- to select "Read Measuring Value Block" (scan tool function 08), and press -Q- button to confirm input.

Indicated on display

Fig 2: VAG1551 Tool Display - Knock Control (2 Of 3)

Press buttons -0-, -1 - and -3- to input display group number 13 (013), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)

Fig 3: VAG1551 Tool Display - Knock Control (3 Of 3)

Check specified values for knock control for bank 1 (display fields 1-4). See Fig 4.
Road test.
WARNING:
- When driving or riding in an airbag-equipped vehicle, NEVER hold the scan tool or other test equipment in your hands or lap while in motion. Objects between you and the airbag increase the risk of injury in an accident.
- During a test drive in an airbag-equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician.
Fig 4: Display Group 13: Knock Control, Bank 1 (Vehicle In Operation)

If displayed values are not as specified in Fig 4, see CHECKING KNOCK SENSORS .
Press -3- button to advance to display group 14.
Check specified values for knock control for bank 2 (display fields 1-4). See Fig 5.

Fig 5: Display Group 14: Knock Control, Bank 2 (Vehicle In Operation)

If displayed values are not as specified in Fig 5, see CHECKING KNOCK SENSORS .

Notes on knock control:

Temporary fluctuations of 12° (crankshaft) are OK.
Knock control is active throughout the entire RPM range, starting at engine loads greater than 30%. When engine load exceeds 30% the actual timing retardation values are indicated.

Fig 6: Evaluating Display Groups 13 And 14
Press -3- button to advance to display group 15.