Burst knock question(s)

[SSbaby]

I'm wondering what the 'best balance' is for setting the burst knock tables.

Currently, my tables are set as follows...

{B6210} Burst Knock Delta Air Mass:

Values range from 0.016 to 0.038 with increasing rpm.

{B6212} Burst Knock Retard:

Set to 12 degrees. Is this too high? I've seen values as low as 2 degrees but this seems to low to be effective? :?

{B6207} Knock Retard Revovery Rate:

Set to 0.80.

Cheers

[GMPX]

Not sure on exact numbers but ideal IMHO is to have maybe 4 - 5 degrees at low RPM with much larger airflow numbers, ramped out very fast. At higher RPM no burst knock esp when MAFless, it can false trigger burst knock.
Others may dispute and they may be correct :?

Cheers,
Ross

[SSbaby]

For those interested, I got good results using the following Burst Knock values after a brief run last night:

Deltas | Burst KR
0.040039 3.999023
0.040039 3.999023
0.040039 3.999023
0.060059 3.999023
0.060059 3.999023
0.060059 3.999023
0.060059 3.999023
0.060059 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023
0.050049 3.999023

Oh, and i also increased my Knock Retard Recovery Rate table values to 0.10 degrees per 4x crank rotation (from 0.06).

I believe better performance is attainable if high-ish Deltas are used instead of the stock 0.20/0.10 in my table for 2001 PCM (VX2 M6). Might wind down the retard values to 2-3 degrees to see if I get better throttle response during kickdown in the taller gears from low rpm.

Either way, I'll brief you on my results.

Cheers.

[Tordne]

I am tracking this with interest :)

I actually zeroed out both the Burst Knock tables and have had better results (from a limited number of runs admittedly).

[SSbaby]

I actually zeroed out both the Burst Knock tables and have had better results (from a limited number of runs admittedly).

It's not the first time I heard about zero BKR giving best results. However, a baby must first learn to walk before it attempts to run. ;)

For safety's sake, I prefer to run at least 2 degrees of BKR... but will also play around with zero BKR.

[zrx1200]

ssb i have never encounterd any burst knock.perhaps i'm a bit tame with my spark?my b/k settings are the same as gts but with less retard 5 max but spose the auto looks after itself a bit compared to lugging a manual?

[SSbaby]

I was aggressive with my spark table but kept getting KR when I mashed the throttle in the higher gears, even with 8 degrees BKR!!! I then decided to adjust the BKR table with values of 12 degrees... someone told me that's too much pre-emptive timing to retard. :shock:

Your Burst Knock tables should be tuned especially if you have a cam installed, otherwise you'll sacrifice driveability or fail to exploit the added benefits. I reckon the trick is in tuning the delta airflow values... if you go high-ish (i.e. in the range of 0.40-0.60 g/s) you can get away with running lower BKR values (2-4 degrees) without having to alter your spark table much.

I don't know about the auto vs manual caper, it might depend on your driving style... what if (in the auto) you hold 2nd and give it WOT, can you trigger KR? :?:

[caver]

Been keeping an eye on this post.Maybe this is one of the reasons I cant run as much advance as I would like on s/c cars.

[ringram]

This was my exact problem, stock was pulling 14deg out for no reason as no actual knock existed. Im in SD mode. I put a stock set of GTS values in which starts off at 8deg and drops away to around 4. So far good results.
Am waiting to get LC-1 in before I do any more sharpening of the BKR knife.

[caver]

The IAT spark table removes huge amounts of timing starting at 35 degC.There is also timing taken away in the ECT spark table at around 80 deg C or so.

Gotta keep an eye on all those buggers or you will be driven insane.

[Tordne]

OK, some results from me.

I have now performed about 7 runs in the car since zeroing out both the {B6210} and {B6212} tables. No other changes to the tune have occurred (i.e. no changes to spark tables, VE or otherwise).

I have also "driven" the car a little harder than I might normally, but have also performed the regular drives to work as well.

NO KR at all on any of these logged runs. Not even 0.09. NOTHING!

Previous to this change I was getting up to 3 degrees of knock in the higher RPM areas. No amount of reducing timing seemed to completely eliminate this. I actually reduced a lot of the table by around 4 degrees to see if that would get rid of the KR, but it did not.

Interesting to see other peoples results.

Cheers,

[SSbaby]

Andrew,

Not disputing your findings. But can I ask how you attained your results?

Did you simulate a drag strip run or were you hovering at 2,500-3000rpm in the lower gears (2nd, 3rd,...) and mash the throttle? Did you also try the same in 5th, 6th gears? I usually get burst knock if I hold 5th or 6th and WOT at 1500 rpm, even with 4* BKR.

If you have performed the tests described, please let us in on your timing secrets. ;) :D

[Tordne]

My original frustration was with getting KR during normal, everyday driving conditions (driving to and from work etc.). I used to get KR when going over a speed hump in second gear and lightly accelerating away from it. That particular situation was resolved in part by changing the commanded AFR, but the burst knock settings have also helped.

So, my testing has basically been around normal driving conditions. My symptoms were also commonly getting KR as the RPM's got up to and about 3000. Accelerating down a motorway on ramp in 2nd or 3rd gear for example. I gave it a boot the other night in 3rd gear, this would have normally given me a few degrees of KR. With ONLY the burst knock settings changed (I promise) these was no KR at all.

As far as going WOT in 5th or 6th, I would totally expect the car to knock under those circumstances as the car will be really unhappy with that situation. I honestly haven't tried doing that. I'll give it a quick try, but I will be completely floored if I don't get any KR.