Logging Burst Knock Retard

[c001074161]

I have an 04 GTO with a 227/234 cam. Knock learn before cam replacement was always around 1.0. I have always used 91 octane which is the best I can get in my area. While trying to get the tune sorted out I had been noticing knock retard and knock learn was usually 0.30 at best. Knock always happened at low load/rpms, leaving a stop sign and tipping into the throttle. Rarely saw knock at wide open. Running stock timing tables and even pulled 5-8 degrees out in the areas that I was having problems with no change. I'm logging burst knock and never see evidence that it is burst knock. I was looking through other tunes trying to compare tables and noticed on one tune that under Spark/Retard/Burst Knock Retard/Enable Delta Cyl Air I had maxed out at 8.0 which seems to be due to the way the description is worded. I of course realized that was my problem. Shouldn't this show up when logging burst knock retard?

[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.

[Mr. Smith]

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.

So could me pretty-much disabling Burst Knock be the reason why my Knock Learn Factor has sat on 0.75 for the last 5 years?

[Hondaeater]

Yes if the knock strategy enables retard and it is "real" knock retard not BKR then Learn factor is effected. You mentioned reducing the Advance by 5-8* ... and it still knocked, reduce another 5* and if still Knocking then you now need to determine the reason for the knock before ruling it out as false knock. If the spark reduction didn't help then put it back in. If it reduced the degrees of retard then get an octane booster like Boostane etc or add some fuel.
Did you use different injectors? Some issues can arise when the MAF and VE tables are adjusted to compensate for poor injector data and the air mass is misrepresented. When that happens you think you are in .XX area of spark table but the reality is you are in a different g/s part of the advance table and there can be a big difference in spark for the "real" fuel/air ratio. Consider adjusting a broader chunk of the timing table where the g/s & RPM has the knock and log for effect. BKR will effect the learn factor but if you have false knock then it doesn't matter. You can reduce the spark to be conservative or use the BKR but if it is not spark related then neither will get the Learn factor back or stop the knock. I hope that helps and I didn't just keep repeating myself lol.

[Mr. Smith]

Yes if the knock strategy enables retard and it is "real" knock retard not BKR then Learn factor is effected. You mentioned reducing the Advance by 5-8* ... and it still knocked, reduce another 5* and if still Knocking then you now need to determine the reason for the knock before ruling it out as false knock. If the spark reduction didn't help then put it back in. If it reduced the degrees of retard then get an octane booster like Boostane etc or add some fuel.
Did you use different injectors? Some issues can arise when the MAF and VE tables are adjusted to compensate for poor injector data and the air mass is misrepresented. When that happens you think you are in .XX area of spark table but the reality is you are in a different g/s part of the advance table and there can be a big difference in spark for the "real" fuel/air ratio. Consider adjusting a broader chunk of the timing table where the g/s & RPM has the knock and log for effect. BKR will effect the learn factor but if you have false knock then it doesn't matter. You can reduce the spark to be conservative or use the BKR but if it is not spark related then neither will get the Learn factor back or stop the knock. I hope that helps and I didn't just keep repeating myself lol.

Thanks.
Sh*tload of info I need to reread 25x for it to sink in..
Will start............... now.

(I'm not the OP btw)
(I f-ing hate this burst knock and knock learn factor SH*T)
(I can't believe you have to go to your "Settings" tab to see if you have thread replies. That's stupid af, HP Tuners tech geeks)

[blindsquirrel]

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