00 Z-28

iTrader: (9)

MAYBE, I'll figure it out one day. Just installed the canned predator program. Getting 3.8 kr @ 4300 rpm. Getting 700 - 780 readings on the 02's cruising, 880 - 920 @ wot. LTFT - bank one = +1 / bank two = +1 cruising, bank one = +3 / bank two = +4 @ wot. Backed off timing 3% still getting 3.8 kr @ 4300 rpm ( pinging is present). Timing usually stays around 28* - 42*, but drops a little when acc. Waitng on James @ RWTD to contact me. Any expertise or comment would be very app.

Thnx

HumpinSS

iTrader: (1)

Long Term fule trims are what the computer does to compensate to keep the engine running at a commanded Air fule ratio (14.6-14.7 closed loop). The computer know how much fuel for the given amount of air and O2 readings it needs to supply the enigine. If it cant meet these requirements it starts to add fuel via the LTFT's and the STFT's. THe reason you want these to be 0 or negative is because at WOT the computer locks in the last LTFTs and automatically adds this on top of any fuel that is needed when the computer is in Power Enrichment mode(PE). You are getting knock retard becasue this still isnt enough fule for the demad that the engine is requesting hence the knock retard. You can see you are getting into a lean condition because your 02's are running around .700 mv or so. I am having the same issue with my car and I have one of three options.

1. MAft
2 LS1 Edit
3 Getting it tuned by a local shop.


My car is stock with the exception of the Air filter, lid, pulleys, 4.10 and a flowmaster. That is all i have done to it for now and I am seein the same symptoms.

jimmyblue

iTrader: (11)

The funny computer WOT enrichment response to LTFT
is a stark reason to get them right, but the LTFT
data is also a direct indicator of how well tuned
your fuel delivery really is - the whole stack of
sensors, plumbing and squirt. When you see a big
value, you know that something is just off, and
yer buddy the computer has to make up the slack.

If you're way off, rich, all you get is some soot.
If you're way off, lean, you get knock. The place
the error is laid bare is on throttle transients
and WOT, where closed loop is out.

If you have consistent mixture error, the only
hardware change to fix it is a fixed MAF or MAFT
(demand side) or bigger injectors / higher fuel
pressure (at max flow) on the supply side.

In software you can mess with various air and
fuel data tables (with the proper tools). These
cal map data can tighten up the fuel delivery
computation to your real setup. But, you have
to know where to start. Predator starts from a
single generic assumption. A car that's 5% off
from the pack, will have 5% less "tuning margin".
And that's what you call someone with +4 LTFTs.

First order, tweaking PE should fix midband
LTFTs and not touch WOT too much as dropping
LTFTs will take away what PE adds - this is good
as you have up to 920mV O2s. You will see more
consistency once you lock zeroes at WOT.

So give it the full +5% PE and a week of driving,
see what square you land on. Too fat? Back off.
Still too thin? Then bother James for a special
fuel tune. But I don't figure he has the time for
being everybody's Tuning Answer Boy. I wonder
what his inbox looks like. I'd guess it ain't
pretty.

waverider

I only have a fipk and my lt's are around 2.34 at part throttle and wot. I ordered a maft but the damm thing is on backorder. Since I'm running very lean at part throttle my 02's are really high, rich. Car runs very weak especially in the heat. Stupid how some ls1's stock are screwed up tune wise. By the way I'm running the STOCK MAF, so ignore the sig.