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Open loop fueling targets and wall wetting

Understanding AFR

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Discussion and questions related to the course Understanding AFR

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Hey guys,

So I was recently experimenting with leaning things out slightly in my WOT range as initially it was targeting around 0.72 to 0.73 lambda in these regions.

I made some fairly conservative changes to the open loop fueling tables which currently look like this:

I havent been revving the car out past ~6k usually so I would actually expect the open loop targets to be hitting the cells in that table that are around

11.0 and 10.94 ( ~0.74ish) for max load. Oddly though, when I log the car through this region it looks like the actual fueling target seems to be more like 10.7 (~0.72ish) @ ~5300rpm. Basically Im trying to figure out why my actual commanded final fueling is a fair bit richer than what I have in the tables.

As far as I can tell there shouldn't be any fueling compensations being applied there and I have also changed the AF #1 learning table breakpoints so that the learned closed loop fuel trims shouldn't be getting applied in open loop. The only thing it seems like it could be related to is perhaps some wall wetting tau functionality impacting the fuel target?

If anyone has any insight on why this enrichment is happening in these regions that would be great.

Attached Files

Yes wall wetting can have a big impact, sometimes over a full point AFR.

The simple solution to determining when it is impacting your commanded fuel target, is logging the wall wetting monitors. Then you know exactly how much effect it's having, and which portion of the wall wetting system are active at a given time, and then can decide what adjustments you may want to make.

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