Originally Posted by
Hondaeater
Burst knock was determined by GM that if certain parameters were met ENGINE IS GOING TO KNOCK and they removed timing before it happened using the Burst Knock table. It WILL knock at that point in the stock config, so 0 or 8.0 in the Delta means you will have to be more conservative in setting the Main spark tables up or Knock learn factor will bias. The Burst knock when set correctly, is used to keep the Knock learn factor from biasing toward the LOW Octane table. If burst knock removes spark advance, which WILL show up as retard in graph, but logging BKR parameter shows it was specifically Burst knock, then the High Octane table is still used and Knock Learn Factor doesn't bias toward Low Octane.
If on the other hand Burst knock was defeated and you have Knock event the bias toward Low Octane thru the knock learn factor happens and you lose performance. Burst knock DOES reduce the timing TEMPORARILY but to prevent the Knock Learn factor from bias Low Octane long term. Again if you didn't have BKR then you would need to run conservative advance to prevent Knock at Tip in and lean transitions.
The ECM always wants the high octane table but Knock learn factor actively bias to the Advance table that prevents engine damage.
VE or Speed density only uses the Low Octane table and MAF only uses High Octane table which is why we make them the same during the tuning process but afterward reduce the Low Octane to give a safety margin when using both fuel models.
Hope this helps.