BKT Flex Fuel modifier.Originally Posted by Higgs Boson
BKT Flex Fuel modifier.
Do they use a physical sensor or is their logic virtual?
James Short - [email protected]
Located in Central Kentucky
ShorTuning
2020 Camaro 2SS | BTR 230 | GPI CNC Heads | MSD Intake | Rotofab | 2" LT's | Flex Fuel | 638rwhp / 540rwtq
2002 Camaro | LSX 427 | CID LS7's | Twin GT5088's | Haltech Nexus R5 | RPM TH400
It should be about three degrees actually. Inferred content x multi x modifier. I'm commanding 4.5 degrees at full conent. At the e70 it should be about 75% of that
In for guide with pictures
A guide would be a great asset. Thanks in advance TunedbyNishan!!
How do you know it isn't adding from flex but pulling from another table? What are you logging? The scanner for ford stuff is not as robust as GM stuff....yet.
It is virtual, or rather "inferred".
It infers alcohol content based on learned stoich AFR.
www.tunedbynishan.com
2018 Mustang GT - 10R80
And.....how does it learn stoich afr? ;-)
The car is in Lambda as you may know, so stoich is always 1. It learns by the amount of fuel it needed to add or remove to continue to achieve a stoich of 1.
i guess you have a point there. ill use my VCM and log spark source and see what its pulling from. My thoughts was that something was putting a cap on it. im pretty sure my tables are setup properly.
IF you have a premium cluster with the LCD you'll see the AFR on there adjust accordingly.
Something akin to this.
https://patents.google.com/patent/US8522760B2
So idk wtf I'm doing wrong but my car just doesn't wanna run the commanded flex timing. i runs only whats in the OP table plus the knock sensor. i looked at the spark tab on a flex fuel f150 eric posted and tried mimicking that on mine and nothing. the car is learning the right AFR so its learning the connect. but just refuses to run the timing. I've changed multipliers and such. I'm not sure where else to look. unless its like someone said the theres something missing
What are your long term fuel trims with ff enabled?
My trims are spot on really
Log your ltft with 93 and a non ff tune then log them with a ff tune
How do the ltft change and how does the stoich value on your car display change?
I'm not asking you for my benefit. I'm asking you for your benefit.
I currently dont have a car with FF flags supported, so I can't tell you unfortunately
If you're thinking that it would incorrectly adjust the stoich to correct for the fuel trims, that's why the adjustment algorithm isn't that simple. Its designed to mitigate that risk. As well, the algorithm runs on a detected refuel event (Fuel level input change > 20%), which I also believe is to help mitigate it changing. Fuel trims should be "learned" in that time period and only be correcting for inaccuracies there.
I would be curious about the same thing though. If it works well enough to detect Stoich AFR without being effected by other issues (say an exhaust leak). If you had an exhaust leak, and it attempted to adjust its stoich and ethanol percent based on it, you could have some negative consequences especially with the advanced timing, raised load limits, etc.
What I am seeing in the Ford and GM Virtual FF tunes, there is none or next to no LTFTs with FF enabled. It soaks them up in the Stoich calc, which is why it is so important to have an accurate airflow model before switching to FF. My LTFT with FF enabled sit at -.08 even though the same tune without FF might be -3 or +5, doesn't matter. The GMs I have tuned with Virtual FF just 0 the LTFT. Maybe it doesn't use ONLY LTFT to adjust to a stoich, but it definitely uses them.I currently dont have a car with FF flags supported, so I can't tell you unfortunately
If you're thinking that it would incorrectly adjust the stoich to correct for the fuel trims, that's why the adjustment algorithm isn't that simple. Its designed to mitigate that risk. As well, the algorithm runs on a detected refuel event (Fuel level input change > 20%), which I also believe is to help mitigate it changing. Fuel trims should be "learned" in that time period and only be correcting for inaccuracies there.
I would be curious about the same thing though. If it works well enough to detect Stoich AFR without being effected by other issues (say an exhaust leak). If you had an exhaust leak, and it attempted to adjust its stoich and ethanol percent based on it, you could have some negative consequences especially with the advanced timing, raised load limits, etc.
I agree that it has to calculate and then stop calculating until refill, but for how long? The criteria are minimums, at least 10 seconds, at least 10 switches, and the refill % criteria. So when does it stop? When LTFT are 0%? That's what I think....0% LTFT means stop calculating.
I don't have logs and I'm still on corn but I'm seeing actual real numbers in my ltft. Won't be off corn for another few days
post the tune?
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