sleeperstyle

iTrader: (4)

i've been fighting kr since i picked up hptuners. it is ALWAYS on tip-in, never partially through a pull (not more than .5kr anyway which is nothing in my book).

i don't have the kr decay or burst knock features in my program since it is a '98 and those tables are constants which cannot be adjusted. i moved the pe tps% from 65% to 40% on pe enable and it has helped some but some times i'll get an instant 3-4* kr which bleeds off.

i had my car dyno-tuned on fri (free dyno time ), got my a/f flat across, so my wot is good and my ltft's are not worse than + 2 in some spots

## my main question is- when the converter is locked up and im accelerating on the highway with it locked up i get kr, sometimes 1* which holds there, sometimes up to 4* kr. this is all before like 2k rpms.. SHOULD I BE WORRIED? my main concern is that the engine is under load, but im pretty sure it would be picking up something else at 1500rpms other than real knock. what would i change to correct this. my 02's are very fat at those points, from 750- 850 and im not even wot so it isn't too lean.

any help is appreciated.

Mitzelj

iTrader: (1)

A few things to think about, 98's had bad knock sensors and is this a vette, if so, bang on your exhaust manifolds and see if they rattle and I think 750 to 850 is actually lean, I've always hears 880 to 910 is where you wanna be. Good luck. Jeff

Another_User

Yeah, you are probably running lean. If so, then yes, I would worry.

jimmyblue

iTrader: (11)

I think most of this will respond to fattening up the low
end of the VE table. Certainly the tip-in knock, especially
if you see the O2s dip as the throttle opens and MAP
rises. This may be at cross purposes with idle, where a
cam will make you want to lean it out. You have to see
what your MAP*RPM are at the start of the lean dip,
and what you run through; in that area bump up VE by a
couple of points, and try it out. After some of this you
should have yourself free of tip-in knock.

750mV is not especially fat. It could be 14.0:1, depending.

You should think about what might be causing a natural
lean condition at the low end. I'm guessing headers may
just have improved the breathing but nobody told the PCM.
But a '98 also has active EGR and if this was removed, but
the spark table adder for EGR is not suppressed or zeroed
there is some significant excess advance that may be put
down.

sleeperstyle

iTrader: (4)

* it is a 98 formula- stock other than lid/'verter/t-stat. i am leaning toward a faulty knock sensor since i get the knock "sometimes" and not any at all no matter what i do sometimes. i can free-rev the car and get kr. do i upgrade to 00-02 knock sensor or what?

i will give the ve table a shot. i would rather not richen up the lower end because my ltft's at idle are -12 to -8, the rest of the time they are pretty good but in the top left of the histogram im pretty rich.

remember im NOT wot when i get this knock so the 02's could be lower than 870mv i would think? when i got my car dynotuned it liked 850-870mv for a good a/f ratio, every car may be slightly different but i know what my car likes- it hovers around 870-880 right now in the wot cells. i agree the 750mv is way lean but that only was in one cell that it was that low (probably the cell that i saw the kr in.

so (jimmyblue) you reccomend about 5 points in the problematic ve areas? i've heard that you need to change the ve table DRAMATICALLY to see any improvements (like 20%)?

jimmyblue

iTrader: (11)

The change needed, depends a lot on where in the
table (RPM) you are. My experience (not universally
shared it seems) is that about idle VE is 1:1 and MAF
is no effect, between idle and 4000RPM the airflow
calculation "blends" SD and MAF inputs with more
weight on the MAF as you go up, and after 4000RPM
it's all MAF except when the MAP is unsteady, then
it all falls back to SD (hence wanting to fatten the
VE table). If the VE table is mostly ignored, so much
the better. You're not looking to alter LTFTs or the
steady state fueling, just make sure that when the
SD tune is "uncovered", it makes sense.

If you have already fixed idle problems by lean-out
you don't want to go backward. But I think it's probably
the 1500-2500 range where you have maybe a little
short VE value that makes transient lean come through.

What about the EGR? Is it hooked up, unhooked and
just code-suppressed, or unhooked and the EGR spark
tables properly flattened?

sleeperstyle

iTrader: (4)

the egr is untouched- no codes no anything (no hacking basically).

im gonna give this a try and see what i come up with.

thanks.