Tip in KR and Burst Knock

[Mitzelj]

I've got a 99 Vette that I'm having throttle transtion or tip in KR with. When I look at the raw excel file, it seems that one 02 is always low(double digit) at that onset of the throttle opening. So I have a couple questions.

Would this be a lean hole in the VE table and would I tweak the primary or
secondary?

99 Vettes appear to have the burst knock table set to a delta of 16 and
then other burst knock table is zeroed out,is this normal?

I pulled a bin from Horist's site and the 99 Vette there is the same as
mine but 99 F-body's have the burst knock info populated as do later model
Vettes.

Any thoughts would be appreciated. Thanx, Jeff

[Ouija]

Did you runa search on "Burst Knock" on here check the thread

;D

[Mitzelj]

Did you runa search on "Burst Knock" on here check the thread

;D

Yep, I 'd seen that, but my BK tables are disabled but I'm gonna turn em on and see what it does. I also fattened up my VE table as well. Thanx, Jeff

[MNR-0]

I love burst knock. It protects against throttole transients that generate lean conditions and knock. But best of all, it helps you off the launch. I call it launch control. You only need it down low. Its safe to zero out the values after 2800RPM, or whatever your stall speed is.

[Mitzelj]

Here's what my research has revealed. My knock
occurs at low RPM to high RPM transtions.
It begins as a single event and the ramps down to
either 0 or stops when the throttle is lifted.

It's onset is unafftected by raising VE values or
reducing spark. I used burst knock and spark
reduction to pull the spark timing at the event to as
low as 10 degrees which resulted in a KR pull to
2.5 degrees total advance.

It's onset is not affected by fuel octane as I have
run the car with 100/104 CAM2 unleaded and still
observed the same KR events.

I have elminated all audible rattles in the engine/exhaust
system.

So, I believe this has to be an engine, valve train or exhaust
related harmonic that is causing the sensors to hear knock when
there is none. This coupled with my understanding that knock
events occur from low octane, excessive advance, lean fueling or
high engine loadings, leads me to believe the knock is false, as it is
most present when the motor spins up prior to a downshift or
against the converter during launch. The event always occurs
prior to the engine actually being loaded and then bleeds off
if the throttle is kept open.

So what I've done is descrease the knock sensors sensitivity
below 2800 RPM in the Knock Sensor Level vs
RPM vs CYL table. This has eliminated all of the KR.

So given that long explanation does anyone agree or disagree?

Thanx, Jeff

[MNR-0]

I concur. I did the same. I keep max. sensitivity from 6000RPM onwards though, but limit the spark pull for each knock event. I enjoy racing, but liek to have my car in one piece too.

As you have discovered for yourself, its a combination of factors that leads to a well tuned car. All tables have their place, its just finding the balance between them all that makes the difference.

[BLOWNZ06]

Here is my question...

I have been fighting a randon knock problem too since I installed my headers on my Supercharged ZO6.

I went and logged several WOT runs.. getting varied retard levels.. I refereced the area on the logs with an excel spreadsheet, calculating delta in airflow.

There were places were the delta was as high as 0.19

Right now my table is set for burst KR delta enable of 0.04... so I adjusted it for the rpm range between 3400 and 5200 where this is happening to 0.20?

Is this the correct move? If I am understanding the table correctly, now I would have to have a delta of greater than 0.20 to enable the burst knock retard?

TIA

[MNR-0]

Here is my question...

I have been fighting a randon knock problem too since I installed my headers on my Supercharged ZO6.

I went and logged several WOT runs.. getting varied retard levels.. I refereced the area on the logs with an excel spreadsheet, calculating delta in airflow.

There were places were the delta was as high as 0.19

Right now my table is set for burst KR delta enable of 0.04... so I adjusted it for the rpm range between 3400 and 5200 where this is happening to 0.20?

Is this the correct move? If I am understanding the table correctly, now I would have to have a delta of greater than 0.20 to enable the burst knock retard?

TIA

Well, yes. But if you dont want burst knock at WOT, just zero it out. Much easier. All you are doing is raising the point so that Burst will never apply, effectively the same as zeroing out the burst knock retard tables.

[BLOWNZ06]

Thanks.. I will try that approach.

Nick

[Mitzelj]

Here is my question...

I have been fighting a randon knock problem too since I installed my headers on my Supercharged ZO6.

I went and logged several WOT runs.. getting varied retard levels.. I refereced the area on the logs with an excel spreadsheet, calculating delta in airflow.

There were places were the delta was as high as 0.19

Right now my table is set for burst KR delta enable of 0.04... so I adjusted it for the rpm range between 3400 and 5200 where this is happening to 0.20?

Is this the correct move? If I am understanding the table correctly, now I would have to have a delta of greater than 0.20 to enable the burst knock retard?

TIA

Burst knock does not show up on the KR PID, it has it's own. What you will see is a timing dip for a frame or two. If you want to see the BK info you need to log the BK PID in the scanner and see what it is doing. Does pulling timing or raising octance help the logged KR at all?? As always YMMV. Jeff

[domestic rice]

7 years later..... Is this method still correct or is there something newer proving these theories wrong?