Forum » Practical Standalone Tuning » Should the fuel VE table stay the same if you only change the targeted AF table or do you need to retune the VE table afterwards?

Should the fuel VE table stay the same if you only change the targeted AF table or do you need to retune the VE table afterwards?

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If the only change you make is to the targeted AF table and select new af targets for the whole map - assuming you have "the right other bits" setup (ha!) should things will "just work" or will "they'll be close" or would it be more of an 'awwh crud "goddamn everything has changed"' type of revision?

Should it work as theory says - if you have injectors setup, ve tables setup, fuel pressure behind the injector doesnt lag behind demands etc - should changing the targeted af table work by itself - or would you need to re-tune the ve table for the engine if you change the target table?

What things apart from injector characterization would allow you to see the correct ve model so you could make changes to say injectors or fuel pump or targeted af ratio or whatever and have the system "just work" ? Or due to modeling reasons - you cant have one ve table for every set of conditions?

(working with haltech e2500 ecu on an n/a k20a)

It should do if the fuel model is decent and the injector characterisation is good. There are many factors that influence how linear the relationship between inj PW and Lambda is and some ECU's have more complete fuel models than others so your mileage may vary, but if the fuel model is good enough and the injector characterisation is accurate then the measured lambda should follow a change in target lambda very closely. In Link after tuning the VE table and other basic influencing factors such as fuel charge cooling effect for instance you can just change the target lambda and the measured lambda will follow very closely. With an NA engine I will generally tune it with a slightly richer target than I think it will need, then after tuning the VE table, just change the target afterwards to see what mixture it likes best. Motec M1 is another ECU that I have used that does it very well too. I haven't tuned an Elite for a long time so I cant remember how well it works with their more basic fuel model.

If you have Instagram here is a short video from one of our dealers showing how it works:

So if you have as much input data as possible for ve table and injectors and sensors as good as they can be - it "should just work" when you change the target table without needing to change the ve table at all - if the setup was good enough

I'll mark this as resolved now - many thanks for the input :)