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Entire fuel tables path

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Old Mar 16, 2008, 11:12 AM
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Originally Posted by GrocMax
Except if its anything like the earlier mits fueling strategy the table is actually grams per revolution, and being a volume air flow sensor there are corrections for baro and temp. The FSM and tech info manuals cover the basics pretty well.

If you are trying to compare from standalone strategies try Motec instead, you can change the fueling strategies from S/D to true MAS and about everything in between.
So the cells are adjusting the g/rev of fuel? I assume you meant the load axis was really a g/rev of air but it made me think. If thats the case, you definitely can set it up to be a target AFR map since AFR is a ratio of grams of air to grams of fuel (for those who didn't know that lol). Also, this would make the MAF Scaling SOOO important, which was something I was working on a while back. Hmm, I'll look into the "fuel g/rev" thing. Thanks. Which FSM btw? The ECU's FSM?

Also, if it actually does calculate off of a g/rev of fuel, it'd have to have a variable for fuel weight somewhere so it can properly scale things in regards to injector flow.

Last edited by Jack_of_Trades; Mar 16, 2008 at 11:21 AM.
Old Mar 16, 2008, 11:41 AM
  #17  
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No, pump fuels don't vary a whole lot, not enough to make a big enough difference that trims can't handle, and oil companies supply a standardized test fuel to OEM's for dev.
Old Mar 16, 2008, 12:44 PM
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I would assume the ECU needs to have SOME variable to make a calculation for the specific gravity of fuel right? Which pump gas would be around 0.76 (760kg/M^3). We run an Injector Scaling of 513cc/min. At that value we're telling the ECU that we can supply 513*4= 2052cc/min fuel max. That equates to roughly 1560g/min of fuel. Granted they are really 560cc/min injectors supplying up to 1702g/min.

I just think its a variable it would want to see, one way or another.
Old Mar 16, 2008, 10:09 PM
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Well, here is the fuel path for my 94170014 ROM. The High Octane Fuel Map is outlined in blue.

Old Mar 17, 2008, 02:48 PM
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Originally Posted by GrocMax
No, pump fuels don't vary a whole lot, not enough to make a big enough difference that trims can't handle, and oil companies supply a standardized test fuel to OEM's for dev.
I have to laugh when the "big one" gave me this lecture about the s*** gas I had purchased when he could not get my "toon" right. I'm not saying that all fuels are created equal but 'cmon.

This was after he went on about my s***ty parts, blah blah blah.

Surprising what ignorance is passed off as knowledge.

Sorry for the OT but I had to say it.
Old Mar 17, 2008, 02:54 PM
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There are a ton of variables responsible for how the FUEL and IGN maps determine their end result. If one setting is screwy, forget trying to get a good "toon". Until every variable is 100% accounted for, we're chasing ghosts. Some of them can DEFINITELY be responsible for the Timing MAps ADDING timing is some cases.

I can track down all the variables connected in the path, I just need to learn how to read the lingo. Most are simple and either add a correction or do nothing at all. They get the inputted data from the previous table and basically say "If the value is below "X", do this. If the value is above "X", do that (or make no corrections at all). Thats what you see in the above graph when the arrow goes AROUND the table instead of thru it.

Last edited by Jack_of_Trades; Mar 17, 2008 at 02:59 PM.
Old Mar 17, 2008, 03:04 PM
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Wow, I think this is the start of something that can be dubbed an "Auto Tuner" where no matter what fuel, injectors, and mods that are changed, the fuel and timing maps will update themselves automatically to ensure we are within some set AFR number like 11.5 plus some tolerance.
Old Mar 17, 2008, 03:15 PM
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What got me started on this stuff was my goal to create a 100% closed loop fuel setup using the analog input from a wideband O2 sensor. I tried finding out how the ECU derives its calculations for fuel now and started to back-track. Found a lot more stuff than I recalled seeing in the tables which seemed to effect the "final values". Knowledge is power and ignorance is a crutch.
Old Mar 17, 2008, 03:22 PM
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Exactly. Instead of changing a cell value based on feedback a wideband gives us, why can we not use the output of the wideband to feed back into the ECU to change those values automatically? Coupled with jcsbanks' real-time tuning patch (once it comes out), this can be made a reality.

Last edited by silex; Mar 17, 2008 at 03:24 PM.
Old Mar 17, 2008, 03:33 PM
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You need to set a "TARGET" value in each cell and the ECU will use fuel trims to adjust it accordingly.
Old Mar 17, 2008, 03:39 PM
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So basically ECUFlash needs to be adjusted so that when it interprets a formula for display - it can reference an address within the rom to make that calculation.

Then when you adjust MicroSec/bit and LD0MPC the display of the tables are also updated using the new formula.

edit: this is OT but which ADC channel are you using as Wideband input, and what is the range on the ADCs? Just curious, I am working on a wideband controller.

Last edited by EvoBroMA; Mar 17, 2008 at 03:45 PM.
Old Sep 22, 2010, 08:12 PM
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Wow, someone PM'd me this article with a question today and I totally forgot about this. With all of the ECU unlocked advancements, I wonder if we are any closer to understanding this?
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