Results after a "profesional tune"

[The1]

no WOT fueling wont be affected by closed loop or BLM's and depending on the cam if the fuel wasn't tuned it'd be maxing out the 20% margin as well.

[antus]

Yeah, wont be able to confirm power enrichment, decel enleanment, lean cruise etc

[j_ds_au]

no WOT fueling wont be affected by closed loop or BLM's and depending on the cam if the fuel wasn't tuned it'd be maxing out the 20% margin as well.

Ah, I see. So WOT is open loop, eh?

Joe.

[Dylan]

Any target afr outside of 14.7:1 is open loop. A narrow band O2 sensor is extremely accurate at that afr.
But very innacurate outside of this. They can be a good tool to verify your wide band as well.

[j_ds_au]

Any target afr outside of 14.7:1 is open loop. A narrow band O2 sensor is extremely accurate at that afr.
But very innacurate outside of this. They can be a good tool to verify your wide band as well.

Forgive my ignorance, but I thought stoichiometric was always the target (ignoring the slight rich/lean cycling that is apparently needed to make the cat working properly). Is it just the case that WOT is too uncommon for the ECU to learn the appropriate fuel trims, or it doesn't even try?

Joe.

[VL400]

In simple terms stoich is the point that all fuel is burned leaving no excess oxygen. Running leaner than stoich an excess of oxygen is present, while richer leaves fuel behind. The narrowband oxygen sensor is able detect this lack of or excess oxygen. But its very binary, it can really only say richer or leaner not exactly X AFR. A wideband is basically a narrowband sensor, but has a pump to add or remove oxygen. How much it needs to add/subtract is proportional to the AFR.

Stoich differs for every fuel type, but as the sensor is detecting oxygen you can still have closed loop even if stoich might be 6.4:1 when running methanol.

Google has a heap of info on stoich and also lambda (stoich = lambda 1).

[j_ds_au]

Yeah, I was reading that narrow band sensors have a range of about 14.4 to 15.0 (referenced to petrol), so stoich is pretty much all that an ECU can target in closed loop. I'll have to do some more reading to see if there's really any reason an ECU would want to target a non-stoich AFR, but if so, it would have to do this open loop, and guess the AFR.

Joe.

[Dylan]

There's lots of reasons an ecu will command an afr outside of 14.7 which is open loop as you said.
That's why it's important to get the ve table spot on so it's accurate.

[madmaxisback]

Great info here guys! Best website ever!