burst knock questions.

[sleeperstyle]

still trying to tune out the little bit of kr i get with my 98 firebird (ls1). all it has is a lid/stall/thermostat/hptuners (well basically)

i have the newer version of hptuners with the burst knock feature for the 98 year cars.

it was set at .050, i changed it to .020 to try to make it give the car less timing during throttle transitions, since i mostly get kr when stomping on it and the car is downshifting to first gear or downshifting to 2nd gear from lockup in OD.

my question is am i going about this the right way? as in lowering the value of burst knock delta-cyl-air enable from .050 to .020. my goal is to get it so i can slam my foot down on the throttle and see no kr no matter what speed im at but im having no luck.

## SHOULD i higher or lower this value to get rid of the kr im seeing at tip-in is my MAIN question.##

btw ltft's are fine (all negative and 0 at wot). stock 98 timing map, which i had altered a while ago to try to cure the kr to no avail. the knock is there sometimes and sometimes not but hardly ever more than like 3.8*. my a/f is also nice and flat around 13.0 which i confirmed on a wideband last year.

thanks in advance- i had given up trying to tune this kr out of the car last year but now im ready to give it another shot.

[jimmyblue]

I moved a truck -up- to 0.020 to get BK to go away, so
you probably have to put the floor lower. To see the
actual delta CylAir, use Excel, make a column that (if
Dynamic Cylinder Air is, say, column P)"

=max((P3-P2)/8,0) and copy/paste so you will have a
vector of delta cylair to look at. Use the max() to clip off
all the negative crap.

Now, you want to "position" the BK delta threshold so
that it is not exceeded by simple RPM run-up; on the
rising face of the VE map surface increases in RPM can
make enough CylAir increase to trip BK if the threshold
is too low. Study the delta vector against what you see
for TPS and RPM movement and pick a place where the
RPM-rising delta will not trip burst knock but a good
throttle blip will.

[sleeperstyle]

jimmy- great advice. im going to be completly honest in saying that im not going to do what you said- too complicated for my feeble mind :huh2: mostly because i never used exel (a spreadsheet if i remember correctly) and i just don't feel like getting THAT deep into it- but GREAT advice for anybody reading this thread or doing a search for burst knock.

so im going in the right direction in lowering it, that is all i really wanted to know. i think im going to lower it a little more till i don't see any kr on tip-in (which i still do at .020), but if it starts to affect performance in a big way i'll bring it back up.

i have always had the feeling that my car suffers from the dreaded phantom knock of the 98 ls1 cars, so i could be wasting my time. maybe swapping in some newer knock sensors could tell me if this is the case?

thanks.

[luv2spd]

We also have the option of desensitizing the sensors a little now if you verify that its false knock.