steveo
03-08-2014, 06:33 AM
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):
**** 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...
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):
**** 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...