burst knock

[smslyguy]

I have the v.e table dialed in and the m.a.f. sensor is re-calibrated and yet i still have burst knock. I zeroed out b6210, but while scanning i notice on the data log that it is usaually pegged at 8.1. I even loaded a stock tune and the burst knock is still there, I thought once you had the v.e. tables dialed in it would eliminate the burst knock. Just to get an understanding on it, do you get burst knock from the calc air vrs the actaul air from being off?
My v.e tables are within + or -1 and the ma.f is the same. Just trying to figure out why. It is not affecting drivability at all just trying to understand it a bit more. Thanks for any reply's. Oh the car is in my sig. just basic bolt ons

[WeathermanShawn]

I have the v.e table dialed in and the m.a.f. sensor is re-calibrated and yet i still have burst knock. I zeroed out b6210, but while scanning i notice on the data log that it is usaually pegged at 8.1. I even loaded a stock tune and the burst knock is still there, I thought once you had the v.e. tables dialed in it would eliminate the burst knock. Just to get an understanding on it, do you get burst knock from the calc air vrs the actaul air from being off?
My v.e tables are within + or -1 and the ma.f is the same. Just trying to figure out why. It is not affecting drivability at all just trying to understand it a bit more. Thanks for any reply's. Oh the car is in my sig. just basic bolt ons

I usually make Table B6212 all Zero's. That will eliminate it.

First off, are you 100% sure its burst knock? Burst Knock has no real relationship with the VE Tables and/or MAF. It is a preventative pulling of timing when a large change in cylinder air mass is detected. I.E., you mash the throttle.

Smslyguy, not everyone agrees with this approach, but I don't like 'enabling' burst knock on a lightly-modified car. If your Spark Tables are dialed in, and you do not get any detectable KR (big difference from burst KR), then zeroing out Table B6212 will do the trick.

Hope that helps..

[joecar]

Post some files.

[N0DIH]

Greg Banish talked about Burst Knock in his first book, grab it and read it. He said it is a phenomon. It is something that needs to be there, you aren't going to get around it as easy as a simple tune, if that was all that is needed GM would just tune the vehicles to eliminate it. WeathermanShawn speaks the truth there.

My LT1 had it, and no way to deal with it. My L67 has tables for it, but factory turned off, but the non SC 3800's have it dialed in and use it. Diff? Higher compression.

Just thoughts...

[joecar]

I have the v.e table dialed in and the m.a.f. sensor is re-calibrated and yet i still have burst knock. I zeroed out b6210, but while scanning i notice on the data log that it is usaually pegged at 8.1. I even loaded a stock tune and the burst knock is still there, I thought once you had the v.e. tables dialed in it would eliminate the burst knock. Just to get an understanding on it, do you get burst knock from the calc air vrs the actaul air from being off?
My v.e tables are within + or -1 and the ma.f is the same. Just trying to figure out why. It is not affecting drivability at all just trying to understand it a bit more. Thanks for any reply's. Oh the car is in my sig. just basic bolt ons

The description for table B6210 says:

When a change in cylinder air mass exceeds these calibrated values, burst knock can be enabled.

My understanding is this:

if B6210 is zero, then any change in cylinder airmass always exceed zero... so this would keep burst knock always enabled (as I understand it).

Instead, zero table B6212 so that when burst knock enables, zero timing will be pulled.

And burst knock retard does not show up in the KR pid... BKR has its own pid: GM.EST_KRB_DMA.

[WeathermanShawn]

Greg Banish talked about Burst Knock in his first book, grab it and read it. He said it is a phenomon. It is something that needs to be there, you aren't going to get around it as easy as a simple tune, if that was all that is needed GM would just tune the vehicles to eliminate it. WeathermanShawn speaks the truth there.

My LT1 had it, and no way to deal with it. My L67 has tables for it, but factory turned off, but the non SC 3800's have it dialed in and use it. Diff? Higher compression.

Just thoughts...

Just to clarify. If you ramp down High-Octane Spark fast enough from lower cylinder air to high in your tune, then in essence you have 'tuned' out the need for burst knock.

For example, I have ran the following High-Octane Spark table on a 11.0:1 CR, with no KR and no burst knock.

I like Joe's idea where you simply put the amount of Burst Knock to zero. Again, you have to have a 'perfect' High-Octane Spark Table. Otherwise, it may just be smarter to leave it 'enabled'. Problem is a any TPS mash may unnecessarily enable it. At least in in this OS, you can mitigate its effect. You just have to work on eliminating any mechanically-induced KR.

Good luck..

[smslyguy]

yes shawn, this is exactly what i did. I was just woundering what causes burst knock or if it is of any concern. I know it it burst knock and not "real" knock and that it is not pulling any timming off anymore since i zeroed out b6210. Just trying to understand as to the "why's" i would be still having burst knock. It shows on the scan that it it constant at any throttle. It did it as well on my stock tune??

[smslyguy]

The description for table B6210 says:My understanding is this:

if B6210 is zero, then any change in cylinder airmass always exceed zero... so this would keep burst knock always enabled (as I understand it).

Instead, zero table B6212 so that when burst knock enables, zero timing will be pulled.

And burst knock retard does not show up in the KR pid... BKR has its own pid: GM.EST_KRB_DMA.

yes joecar i am logging that pid GM.EST_KRB_DMA for burst knock only. I did however just zero out b3610 and not b3612 and that did infact elimenate all my burst knock. Just a thought it worked on my car??

[WeathermanShawn]

yes joecar i am logging that pid GM.EST_KRB_DMA for burst knock only. I did however just zero out b3610 and not b3612 and that did infact elimenate all my burst knock. Just a thought it worked on my car??

Just for clarification smslyguy. You said you zeroed out B3610? What OS are you running? On mine that is a PE Delay RPM Bypass. Is that what you meant?

Thanks..

[joecar]

The difference between BKR and faster octane scaler ramping is that BKR tries predict if knock will occur and avoid it, whereas the faster octane scaler ramping is after the fact...

Exactly what N0DIH said, knock may or may not occur on a load increase, but GM thought critically enough about it to add extra code/tables to try to avoid it.

Some people can get away with zero BKR, others can't, depends on their engine and conditions.