ran into a weird thing today.

i've decided to target a 12.9-13 AFR in power enrichment, which is considered a 'safe' range for max power by pretty much everyone that tunes aluminum headed LT1s.

i got it really damn close, but i noticed average around 3200-3600rpm was swinging a bit rich, 12.5 or so.

i reduced the RPM AFR corrections by hex 0x01 @ 3200 and 0x02 @ 3600. this is less than 1% correction. i figure even if i overshot the mark, i'd be happy with a 13.1 or 13.2 average.

i left the other cells alone.

i matted it up a hill, and it broke right up after 3500 rpm, and wouldn't get over 4500rpm (it acted like it was on fuel cut).

reviewing the logs i found this was due to a lean condition.

here's a static analysis of my average AFR (ignore the low rpm stuff, i use PE for open loop idle):

Code:
**** Wideband AFR (Average) vs RPM during PE ACTIVE ****

RPM    0 -  400        0.0    0 Counts
RPM  400 -  800       13.9    2562 Counts
RPM  800 - 1200       14.4    191 Counts
RPM 1200 - 1600       14.1    1 Counts
RPM 1600 - 2000       15.2    1 Counts
RPM 2000 - 2400       12.9    6 Counts
RPM 2400 - 2800       12.8    20 Counts
RPM 2800 - 3200       13.0    21 Counts
RPM 3200 - 3600       12.9    47 Counts
RPM 3600 - 4000       14.0    26 Counts
RPM 4000 - 4400       15.9    22 Counts
RPM 4400 - 4800       17.9    11 Counts
RPM 4800 - 5200        0.0    0 Counts
RPM 5200 - 5600        0.0    0 Counts
RPM 5600 - 6000        0.0    0 Counts
RPM 6000 - 6400        0.0    0 Counts
RPM 6400 - 6800        0.0    0 Counts
obviously it went completely lean.

now i'm not discounting the possible coincidence that my fuel pump died, or my ign coil might have finally flunked it, and i haven't put a fuel pressure gauge on it yet... but it ran perfectly well yesterday.

isn't it a f#*^ed up coincidence that the RPM that it started flaking out at is exactly in the range i just tweaked the AFR table? is it possible this is some kind of math error in the bin? i can't imagine why though...