Ignition timing of the 928S4 GT and GTS is handled completely by the EZK ecu.
One of the nice features is that it tries to advance the timing as far as possible until knock errors occur. As soon as knock errors occur the EZK decides to retard the timing in steps of 3 degrees to a total of 9 degrees.
When detonation knock is detected, the ignition advance on the affected cylinder(s) is retarded almost instantaneously by 3 degrees. If knock continues, then another 3 degrees retard is applied and this is repeated up to a maximum retard of 9 degrees. If detonation ceases, then the ignition is slowly advanced in small steps back towards the value in the main maps. This process can take at least 10 seconds.
A faulty Hall or knock sensor will retard the ignition by 6 degrees from the mapped value above 50% load, and above 2000rpm.
Note that if a knock sensor or Hall sensor fault retards the ignition, then detonation knocks are not logged on the knock counter, and the knock retard system is disabled
This retard is only carried out on the cylinder(s) that have detonation. The EZK can differentiate which cylinder is knocking, as long as the knock and Hall sensor signals are present.
I don't have very precise data but advance timing is approximately like this:
1000 rpm: 0 deg
1500 rpm: 18 deg
2000 rpm: 24 deg
2500 rpm: 28 deg
3000 rpm: 33 deg
This is not what I measured but found on the internet as part of discussions, so to be verified....