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Discussion Starter · #1 · (Edited)
I originally started to explore tuning the MAP tables in hopes of cleaning up my AFR’s. The 3x’s MAP tables can be found in Fuel, as they provide the basis for establishing Load. This Load is then applied to the all the Fuel tables (with RPM as the other cross reference point) to establish your AFR’s. Many, if not most, people take the general approach of using the fuel maps as +/- to establish desired AFR for WOT. What if you could set an AFR value in your Fuel table, and it directly corresponds to an actual value rather than a +/- value? What if you could get rid of the lurching and bucking at slow speeds? What if you could narrow the apparent disconnect in Load between MAFcalc and MAPcalc? This is especially important for SST equipped vehicles, in that the SST seems to use anticipated Load for…..well everything! I wanted to put this out there, how I went about getting to this point, to let others who might be inclined try and see if they can replicate the same results I’ve achieved. This is something that can’t be done in a generic base-map sort of way, it’s for self-tuning. It’d definitely time consuming (not something that can be done in a 2-3 hour dyno session), but the resulting smooth driveability and easy of future tuning are worth it to me. If you are the type who finds it necessary to smooth EVER table in your ROM, this is for you, lol!
Step One: Establish your MIVEC and Boost Maps
The load as registered by our cars is directly related to the volume of airflow, i.e. Volumetric Efficiency. Boost and MIVEC play the largest roles in this, due to the dramatic affect these can have on cylinder volume. For example, based on my Boost and MIVEC curves there is a dramatic increase in airflow starting at 2500rpm, and carries to 6000rpm;

Step Two: Log RPM/Load/psi
After determining your airflow, you need to log. I use about 100,000 lines of logs over several different days and many different driving styles; it may sound like a lot, but it’s only a couple hours worth of logs. The goal is to hit as many RPM/psi combinations as possible, so you can get a good idea of what Load is actually doing. Take all this data, drop it into excel and create a pivot table; set it up exactly as the MAP tables, and change Load to ‘average’. To make my life simple I group the RPM’s by increments of 250 and psi by 0.5’s;


Step Three: Scale your MAF and Calibration Table
First, you will need to set the Calibration Fuel Map to 100, otherwise the ECU will spit out a % of the Fuel map. Second you need make sure your MAF is scaled properly. Swiftus has an awesome tool to help scale you’re MAF, check out his thread for details. The only other thing I do after using his tool, is take the two columns of data and dropping them into excel. Then I create a scatter plot and tweak the values slightly just so that the graph has the cleanest curve I can make (yes, I’m totally OCD);


Step Four: Create the MAP Table
This is where things get interesting, and where I had the most difficulty. It’s not possible to hit all the cell combinations by DD and some spirited driving. This is where knowing your MIVEC/Boost curve comes in real handy. The stock MAP tables look like this, EVO and RA respectively;


Many take the first step of smoothing, and get something along the lines of the top graph. But based on the logs, and a continuation of the how the Load was being plotted, I came up with the bottom graph. Neither one is correct, and if used will have some ‘odd’ side effects (letting off the throttle, idle, WOT shifting, etc);

I experimented with about a dozen variations, but kept getting unintended side effects. Until I finally figured it out; Load will rise at one rate while in vacuum, and a different rate in positive pressure. The final graph that seems to have solved all my problems looks like this;

There are a couple of key features that you need to adhere to: 1) below 1000rpm needs to drop off substantially as shown; 2) the angle of the Load increase needs to change when crossing into positive pressure; and 3) keep idle as close to stock as is reasonable. This allows me to have actual AFR within 0.3 of whatever value I drop in my Fuel Map (close enough, lol):
 

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Discussion Starter · #2 · (Edited)
I fully expect this to rattle more than a couple cages.
Warning's First: This has not been tried on a GSR, only on an SST
Logically I would think that for a GSR there shouldn't be a problem, since all the "odd" side effects I worked through should only be relevant to the SST. But I can't guarantee this, so go one step at a time and keep an eye on things :shades:
Second: if you read the post and didn't understand a significant amount of what I wrote, please please do not attempt any of this! There really are numerous ways that something can go wrong, and w/o knowing exactly what is being done it would be extremely difficult to try and fix it.
And Finally: For the LOVE OF GOD, do not drop in the same values in your ECU as can be seen in the above examples. This should not need clarification.
 

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Discussion Starter · #10 ·
I'm not a big fan of interpolate, because it makes everything flat. It takes the first and last values, and creates a straight line. I find that this engine prefers curves to straight lines (boy, that doesn't have any connotations:bowlol:)
I tried interpolate for a couple of the 'experimental' MAP tables, but these had problems when letting off the throttle.
 

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I'm not a big fan of interpolate, because it makes everything flat. It takes the first and last values, and creates a straight line. I find that this engine prefers curves to straight lines (boy, that doesn't have any connotations:bowlol:)
I tried interpolate for a couple of the 'experimental' MAP tables, but these had problems when letting off the throttle.
that must only be true for your car. I have used interpolate on tons of maps with many cars with no issues
 

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Discussion Starter · #12 ·
It's all a matter of how you set up your other tables. It's not that the car is unresponsive to flat tables, it's just MORE responsive to curved tables. Consistency is the big thing, if your boost curve slope is flat, then so should be your timing/etc.
 

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Discussion Starter · #18 · (Edited)
Yeah, my prior tables only had values up to 5500rpm. But I got to do a good 10 WOT pulls. You can see how badly my stock catback (2.38" argh!) is killing my top-end; above 5000rpm my car is choking when psi is >20.
Another interesting phenomenon can be noted; look closely at where peak Load occurs in each psi/rpm range. As the psi increase so does the rpm at which peak load is achieved (a slight diagonal "hump"); if I had a true 3" cat-back I would anticipate the peak Load to shift a bit more as well.
 

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Discussion Starter · #19 ·
So I've had a slight problem with leaning out on up-shifts in 1st and 2nd, but I think I finally got it resolved. It still leans out a little (no more than 0.5-1.0 afr, which is for a half a second, and reasonable in my book), but there are no longer any side effects. I would occasionally get a real bad leaning out in the 1st to 2nd up-shift, causing the car to fall on it's face for a split second (AFR of 17-17.5 :mad:)
But I think I've figured it out by changing my MAFhz bins cross-over points. About 2 months ago I changed the Open/Closed Loop X-over to 100 load max, but the MAF bins were still left at ~140-160 load (350). I started digging into my logs and noticed my fuel trims were fighting me in one small area. It seems like the fuel trims were trying to correct all the medium throttle driving (80-150 load), despite going to Open Loop at 90-100 load (when the FT no longer had a say in the matter). So when I shifted it was quickly dropping down into this small region of -7 fuel trim (I apparently didn't look closely enough to this region, as I spent such little time in it :duh:).
Reset the MAFhz bins to 300 instead of 350, and the fuel trims this morning settled on -1.1 LT w/ a +.7 ST for that small region, success!! :dancebanana:
I also increased the LBIT to -10 instead of -20 (SST), not yet sure if this is "helping" with the afr during shifting.
 
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