Cheers Adam, yeah I am pretty familiar with how the Link does it's base fuel calculations - or at least with how the documentation states it does it, and have been tuning them for a few years now so thus far I think I am reasonably familiar with it though absolutely accept that I don't know EXACTLY how it works so understand I could be incorrect. All the documentation and logging seem to indicate that the MGP value recommended to be used in the fuel table look up is "MAP - BAP" and that is what I am suggesting isn't ideal. Just to be clear here, I'm talking about looking up a value from the fuel table - NOT the fuel calculation done after the fact. I understand the Fuel=MAP part of the fuel equation later down the line deals with baro etc correction, but if the VE or PW value looked up from the main fuel table in the first place is incorrect then it's just doing good calculations on the wrong data. Also, I realise that in most cases people probably won't have any real issue - however to show where and how there could/probably would be issue if you are being pedantic I threw together a graph showing how far off the "MGP" look up would be from what it SHOULD be looking up if you had a properly corrected load look up. This example assumes a car was tuned on a "typical" day at sealevel, say 1013ish hPa - the X-axis is to show different ambient pressures, each line represents manifold absolute pressure and on the Y-axis you can see the error (+/- x kPa) that the fuel table look up would be for that given MAP and BAP combination. It shows that in any situation the baro pressure is exactly that every load point will be on point, however the more baro correction involved, the greater the error. Unfortunately I don't have the ability to take a car with a Link in it for a drive to Taupo and back to Wellington to get logging to prove the theory, a bit of a shame as timed right this low coming through could really offer some pretty sweet barometric pressures if you were at a decent altitude I've also attached a screenshot of some code from one of the freely available MoTEC M1 Packages showing they do the same thing as what I am suggesting/requesting. Obviously, if this change happens this can't be a "fix" as any fuel map done using gauge pressure would need the fuel table to be remapped - it would be a different kind of load option. Hope this explains what I'm getting at and why, let me know if there is anything clearly wrong with what I'm saying - especially if the Link actually does something to deal with this.
Hi Guys, Things are way too busy here at the moment for me to give this proper attention but I will take a closer look sometime in the next couple of weeks when some of the other staff are back.
Why not link to the original discussion? https://www.facebook.com/groups/737420992943719/permalink/1530326236986520/ I'm fairly sure there's more to Link's modelled fuel equation than what Andy is talking about for his adap stuff. When you setup a "VE" fuel table with adaptronic it doesn't take into account the fuel type or fuel pressure for instance. Link/Vipec and Adaptronic are the main platforms I work on.
Adam is correct, changing the VE value (fuel table 1) or the charge temp value (charge temp approximation table) will have an effect on the value of 'Air per Cyl Estimated'.
Dan Bailey got a reaction from krohelm in MAP/BAP pressure ratio as fuel table load axis
