Air fuel code for scangauge

Jordo!

Is that a transformed value derived from the narrowband O2 voltage? In closed loop, all the ECU cares about is seeing the O2 hover around .5 volts (i.e., ~14.68 AFR / lambda = 1.0).

There's pretty much no way it can run too rich or too lean in closed loop (fuel trims will correct) unless something is really fvcked up, in which case you'll get a CEL.

In open loop the AFR will be whatever was tuned from the factory without the narrowband commanding any adjustments (except probably for a long term trim that carries over that is).

Say what? Is that a sustained AFR or only an occasional blip (e.g., going lean on tip-in)?

If you are seeing stable AFR's that lean under heavy load (i.e., WOT, high RPM's) GET OFF THE THROTTLE! You may very well get massive detonation and kill a piston or spin a bearing in short order.

Assuming that value is accurate -- best to confirm with a good wideband O2 either on a dyno or one you can buy (e.g., AEM UEGO)

You do not want to see anything leaner than ~13.5 under heavy load, N/A and a bit richer would be preferred for best power.

Especially if you are using 91 AKI instead of 93... with 93 anything south of stoich is probably okay (N/A), though not best for safety or power.

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