Functional questions...

[SSpdDmon]

Two questions really....what exactly do these settings do:

Trans - Throttle kickdown: What's the difference between a kickdown and a downshift? It says a kickdown will be performed if the throttle exceeds the values in the table. But, mine are all 100%, which leads me to believe it's disabled.

Spark - Burst Knock: How does this actually function? I zero'd out the table like Tordne said he did. Maybe it's my imagination, but the car feels a little more peppy and I didn't see any more KR than normal (still working on the spark table).

[caver]

Kickdown at 100% throttle means your foot has to be on the floor before it kicks down.

[SSpdDmon]

Kickdown at 100% throttle means your foot has to be on the floor before it kicks down.

Ok, but what's the difference between a "kickdown" and a downshift? If I put the throttle to 90% at 40mph when it's in 3rd or 4th, it will drop to 2nd because of the part throttle tables. I don't need to give it 100% for it to do that.

[Tordne]

Spark - Burst Knock: How does this actually function? I zero'd out the table like Tordne said he did. Maybe it's my imagination, but the car feels a little more peppy and I didn't see any more KR than normal (still working on the spark table).

Basically the way that I believe this functions is that it determines the difference in air mass and if it is >= the value in the B6210 table it will subtract the amount of spark in the B3612 table in an effort to proactively prevent the onset of knock.

If you log the GM.EST_KRB_DMA PID you will see various amounts of spark being retarded, which I guess you will ultimately feel in the seat :)

I have tried many times to put values in here, low numbers, high numbers..... Basically in every occasion I have found that when I enable BKR I actually get several more instances of logged KR. The last time I enabled BKR I logged up to about 9* of KR (didn't hear anything). I NEVER get anything like that with BKR disabled (0'd out).

Cheers,

[joecar]

Kickdown is a forced downshift (aka detent downshift) when throttle hits (or exceeds) D0960, D0961, D0962 (100% in your case), regardless of the PT downshift tables.

Burst knock: when the PCM sees a sharp rise in cylair, it reduces timing to pre-empt the possibility of knock;
if the cylair mass change ("delta") exceeds B6210, then B6212 is used to pull timing.

Edit: dang, everyone's quick, Andrew you all beat me by a few seconds...:cheers:

[joecar]

Ok, but what's the difference between a "kickdown" and a downshift? If I put the throttle to 90% at 40mph when it's in 3rd or 4th, it will drop to 2nd because of the part throttle tables. I don't need to give it 100% for it to do that.Prior to computers, some transmissions had a WOT position switch or WOT cable position ("detent") which when hit forced the downshift (if the MPH was below the threshold); when the switch/detent hit, an extra valve was moved to boost the pressure regulator into increasing line pressure (to hold the apply components tighter).

tables D0960, D0961, D0962 are the "detent" throttle positions that the PCM uses;

the terminology stuck, "kickdown" means WOT downshift, and "downshift" means PT downshift (no, not circular definitions).

[Tordne]

LOL. Got to get my post count up you know so I get up early to try and catch the good worms :muahaha:

Have you found the same thing with Burst Knock though, that I actually appears to do the opposite of it's intended function? I have read heaps of posts about it when running in Speed Density. Don't know if it works better when teamed up with a MAF.

Cheers,

[SSpdDmon]

Cool...thanks for the info guys. It looks like I'm going to leave BKR zero'd out since it's gotten rid of most of the KR I was seeing. :)

[Tordne]

Most of my erratic logged KR was resolved through the following:

1) Disabling Burst Knock Retard
2) Installed a PCV Catch Can
3) Went one heat range colder on plugs (NGK TR6's).

I still get some logged KR, as you would expect to. But it is all basically false knock.

[joecar]

Andrew,

The few times I changed KRB, it seemed to just subtract timing every time I touched the throttle, so I left it stock; maybe now I'll try to zero it and see what happens; I was having real knock which I seem to be able prevent (pretty much) by running PE richer at around 4000 rpm, I'm still playing with this...
http://img83.imageshack.us/img83/4469/pe2rs.png

[Tordne]

Joe,

Are you running Custom OS?

I am running a V# Custom, and am using the B3647 table for fuelling exclusively (PE disabled). I see to be able to get away with 12.5:1 max enrichment (1.17 EQ).

I'd be real interested to see your results with Burst Knock disabled. I found that most of my knock just vanished :).

[joecar]

Joe,

Are you running Custom OS?

I am running a V# Custom, and am using the B3647 table for fuelling exclusively (PE disabled). I see to be able to get away with 12.5:1 max enrichment (1.17 EQ).

I'd be real interested to see your results with Burst Knock disabled. I found that most of my knock just vanished :).Andrew,
no, not yet, but one day soon :bash:; I'll zero BK and I'll log my commute next week. :cheers:

[SSpdDmon]

Andrew,

The few times I changed KRB, it seemed to just subtract timing every time I touched the throttle, so I left it stock; maybe now I'll try to zero it and see what happens; I was having real knock which I seem to be able prevent (pretty much) by running PE richer at around 4000 rpm, I'm still playing with this...
http://img83.imageshack.us/img83/4469/pe2rs.png


I was always under the impression that this is what you're supposed to do. I have peak tq set close to 12.2~12.3AFR and lean it out just like that to 12.8 at peak hp.

[joecar]

I was always under the impression that this is what you're supposed to do. I have peak tq set close to 12.2~12.3AFR and lean it out just like that to 12.8 at peak hp.Hmmm... so I am on the right track then, thanks. :cheers:

[oztracktuning]

On the dyno last week made 275rwkw (368rwhp) on a Dynolog dyno - much less generous than a dynojet.

The car has burst knock set to zero and made best power at around 12.5 afr. This was both in the tailpipe and on my wideband pre-cats. The car however did want to run richer on the dyno by about 0.3-0.4afr points - so i used the bi-directional controls to fix that.

Car has 26.5 at peak torque and 28.0 at peak power - has 160 thermostat as well. On dyno was 82 deg ECT and 22 c or so IAT