Knock Control, Checking

Knock Control, Checking

If a malfunction entry relating to "knock control stop reached " is made, perform the following checks:

Special tools, testers and auxiliary items required

• (VAS5051) with (VAS5051/1)





Test sequence

- Connect testing and information system (VAS5051 ) and select vehicle system "01 - Engine electronics" in selection. Refer to => [ VAS 5051, Connecting and Select Functions ] VAS 5051, Connecting and Select Functions. Engine must be running at idling speed.

Display on (VAS5051):





- Under - 1 - select diagnostic function "08 - Read measured value block".

Display on (VAS5051):





1. Enter display group max. input value = 255

- Enter "020" for "display group number 020" in zone - 2 - and confirm entry by pressing Q button.

Display on (VAS5051):





- Check indication in display fields - 1 - to - 4 -.





• The numbers displayed in display zones 1 to 4 represent the actual ignition timing retardation due to the knock control of the individual cylinders. The ignition angle retardation is carried out late in °CA (crankshaft degrees).

- To change to display group 021, press s button.

Display on (VAS5051):





- Check indication in display fields - 1 - and - 2 -.





• The numbers displayed in display zones 1 and 2 represent the actual ignition timing retardation due to the knock control of the individual cylinders. The ignition angle retardation is carried out late in °CA (crankshaft degrees).

- Exit function "08 - Read measured value block" by pressing arrow button.

Evaluation of ignition angle retardation.