Hmm, interesting. So the knock test can add more timing then tables and scalars indicate. Is the amount controllable? Or is it just not broken out in this definition?

Some more clarification and questions. If it is the knock test, why does it never appear in the first drive cycle? Are the test 'results' stored in non-volatile memory afterwards? That could explain the behavior.

Without logging, i'm flying kinda blind right now, but more detail. The just above cruise acceleration was one example. Once I achieve this ping state, it continues to happen on any light acceleration. From stand still, around town, etc. Not just highway cruise. All said previously applies. Good for 1-2 drive cycles.

I pulled 6 degrees further into the spark table. Have it now up to 65. Morning drive was good again. Will see what happens going back.
The main spark table is labeled RPM vs Load. But the table units show Kpa which in Ford speak is only manifold pressure, not really LOAD. Are they one and the same for GM. Some of the stuff I need clarification on. Some tables use Kpa and other speak vacuum and look like they are in inches of Hg.

In any case, best I can tell with the hand held scanner which only read MAP voltage, the ping tends to occur around the 2.45-2.6 volt range. Is there a way to correlate that to the spark load table easily. It's about 1/2 the voltage so does that roughly equate to the 50 column in the table? If the table is not really LOAD but just MAP in Kpa, then it might be a simpler extrapolation.

Thoughts?