Running the ARAP bin gives me 12.5 A/F on my scanner. That's where you want to be for WOT, right? I'm doing WOT plug chops and it looks a little lean, so as I add % to this table my scanner shows that I'm getting values now around 11.6. I haven't seen much difference in the plug color yet. Does the A/F scanner value at WOT really mean anything? I could really see the O2 values increase with each chip burn. I increased fuel and did plug chops in three steps from the ARAP table values of -3.9 to 5. The O2 started at 875 and wound up at 935.

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'87 Formula WS6 - ZZ4 Crate TPI, Scroggin-Dickey ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel base, ported plenum, Edelbrock 58mm TB, Crane Fireball ignition, SLP cold air, SLP 1 5/8 headers, !cat, Summit exhaust cutout, Walbro 255, Koni yellows, Hotchkis panhard & LCA's, 9 bolt w/3.27's.

 

You never, never, never tune to get a particular AFR. You tune for best performance, measured performance.

Looking lean can happen with some of the strange brews of gas floating around. About the only fuel that burns with the right color anymore is race stuff.

 

Scanners cannot measure TRUE AFRs. They only report estimated AFRs which most often will be off by a significant amount. That number allows you to get some insight into what the computer is shooting for. The only way to get a true AFR is via a Wide Band O2 sensor.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Grumpy, with that being said...it sure makes it hard to use plug reading for anything other than "significantly rich" or "significantly lean". I've gotten rid of any knock, my BLM's are close, and the plugs are white even though I've tried adding fuel at WOT. I'm thinking I must be in the region I want to be. Performance meter says I am, but I don't trust it. I'm using the 1/4 mile function in Moates software and it gives me 12.7 @ 108. Maybe I need to break down and buy a Gtech. I guess I'm "lean paranoid" because I'm still running the original 95K mile 22lb injectors, when I know I should put in some SVO 24lb'ers to bring my pulse widths down (~10.8).

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'87 Formula WS6 - ZZ4 Crate TPI, Scroggin-Dickey ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel base, ported plenum, Edelbrock 58mm TB, Crane Fireball ignition, SLP cold air, SLP 1 5/8 headers, !cat, Summit exhaust cutout, Walbro 255, Koni yellows, Hotchkis panhard & LCA's, 9 bolt w/3.27's.