Pete_89t2 Posted February 13, 2022 Report Share Posted February 13, 2022 Here in my part of the USA, pump gas that is readily obtainable is typically an E10 ethanol blended gasoline. According to my flex fuel sensor, the actual ethanol content in my fuel will vary from about 8%~10%, which appears to be a seasonally dependent figure - I'm observing that refiners put less ethanol in during the cold/winter months (8% or so), and more in the warm/summer months (up to 10%). Given the above, I've set my fuel's stoich ratio in my G4+ Fury at 14.13 to 1, which I believe is the correct value for E10, and used the recommended gasoline values for all the other fuel related parameters (i.e., fuel density @20*C, fuel density temp coefficient, etc.). My car seems to be pretty happy with that setup, and the CL Lambda corrections are small, though I wonder if seasonal tweaking of my stoich ratio would improve it. Since my fuel's ethanol content varies a little bit between seasons, would it be worthwhile to tweak my stoich ratio each season? For example, 14.13 for summer (E10) and 14.xx (E8-ish) for winter? Would this make much of any difference for the modeled fuel equation mode? Next question probably belongs in the Wish List section, but it is it possible to setup a simple 2D table to grab Stoich Ratio as a function of % Ethanol Content? I'm thinking that would be useful in the case where you might be able to fill your tank with pure gasoline (E0) someplace, and have the ECU automatically adjust your stoich ratio for you (assumes a flex fuel sensor is fitted). Quote Link to comment Share on other sites More sharing options...
essb00 Posted February 13, 2022 Report Share Posted February 13, 2022 Your wish is already there in 'Modeled - Multi Fuel' fuel equation mode. Quote Link to comment Share on other sites More sharing options...
Pete_89t2 Posted February 17, 2022 Author Report Share Posted February 17, 2022 On 2/13/2022 at 12:21 PM, essb00 said: Your wish is already there in 'Modeled - Multi Fuel' fuel equation mode. True, but that seems like an awful lot of additional tables to fill out & tuning work to do just to be able to fine-tune your stoich and fuel related parameters to handle pump gas that has an ethanol content of 8~10% the majority of the time, and the occasional tank of pure gasoline (E0) you might find in those few places its still available. I'm a newbie at this, but my understanding is when you enable "Modeled - Multi-Fuel", you basically are doing a tune for pure gasoline (or E10, or whatever your primary fuel is), and then you need to do a tune for pure ethanol (or as close to that and you can get to that), and both tunes will need their lambda/AFR target tables, spark timing tables, boost control tables, etc. fully tuned before multi-fuel blending based on ethanol content % can work effectively. What I'm looking for would be a simplified version of this based on 2D trim tables, that could tailor just the fuel specific parameters of stoich ratios, fuel density @20*C, fuel density temp coefficient, etc. as a function of ethanol content % within a narrow range, say 0% to 15%. In a case like that, you really wouldn't need to change lambda/AFR target tables, spark timing tables, boost control tables, etc.. Quote Link to comment Share on other sites More sharing options...
INSW20 Posted February 17, 2022 Report Share Posted February 17, 2022 For that small of a change I wouldn't worry about it. Tune for E10 and then when you're running E8, you'll be the tiniest, tiniest bit richer. On my modeled multi-fuel, I'm tuning for E85 (actual about E75-77) and E10. It'll be very rare I'll ever fill with E0, and I'll never fill with E100, so my multifuel blend ratio goes from 0-100% so I can plug in pure gasoline for fuel 1 and pure ethanol for fuel 2. Then my Fuel Table ratio (and others) are 0% at about E20 going to 100% by E70. However, for what you're doing, you could set up modeled multifuel and you don't have to enable dual fuel or ignition tables or anything like that. Then you just set your target lambda, and it'll take care of the adjustment based on E content. If you're never going to higher E contents, then you won't need to retune on an additional fuel. Quote Link to comment Share on other sites More sharing options...
essb00 Posted February 17, 2022 Report Share Posted February 17, 2022 I believe this simple sample setup would work for you - fuel main for E10, multi-fuel for E8. It would though be best if you use an ethanol % sensor so you won't have to select the switch manually. Difference would be too small to notice at ethanol 2% variation. It would be safe to just tune with E10 then forget about it. Quote Link to comment Share on other sites More sharing options...
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