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Title: ME7.1.1 fuel consumption scale (KVB) Post by: nugentp on October 20, 2020, 06:00:27 AM Looking at the alleged KVB values for the BCY and BBK engines I found something unexpected.
The fuel flow rate referenced on the BCY (C5 RS6) is around 353ccpm - thats a lot lower than what those injectors actually flow at 4bar petrol - spec is 390ccpm. The value of 353 is more believable as heptane at 3bar. Meantime on the BBK original chip I see 240ccpm referenced and thats a little higher than the nominal 230cc spec at 4bar with petrol. The figure of 240 is pretty well on the spec for heptane at 4bar. Wondering if anyone can confirm which method is correct. I was expecting KVB to reference the fuel flow rate in respect to petrol unless some other calcs do a nominal conversion from heptane spec to petrol. Ahh - in both cases I was uses map pack guidance of multiplying the eprom byte value by 3.046875 and I have no way to verify if that is correct for either ECU type. Title: Re: ME7.1.1 fuel consumption scale (KVB) Post by: nugentp on October 21, 2020, 05:31:50 AM A little extra information finds that the accompanying FKVA value is 1 on the BBK (B6S4) while it is 0.5 on the BCY (C5 RS6). I would need to do further brain surgery to try and work out the impact of that. I did see a formula on the S4 tuning wiki in regards to fuel consumption for the ME7.1 ECUs but its not exactly trivial to calculate even knowing KRKTE on both platforms.
My first approach will be to scale KVB for 390cc on the BBK map when running with RS6 injectors and see how accurate that is (or not) on the long term MPG display. Not exactly a critical problem if its wrong but one aims to be as accurate as practically possible. |