I'll do my best. I have some experience with the EVO style but more with CarBerry/Subies.
Load is calculated by a metric fuck ton of variables, but it is mostly a "torque to load" conversion. This means the engine calculates the amount of torque it is producing (or, in overrun, receiving) by using a ton of variables (I know you are asking for all of these, but there are really only a few worth mentioning, because some of them get as complex as "turbo backpressure" and airflow through various manifolds - basically models). Most of them make sense and there is no need to change them. Those include friction loss, mechanical components, etc. The ones you
can change are the ignition timing, VANOS, Valvetronic, airflow, air temp, barometric, blah blah blah.
Long to the short - It determines the torque it must output (or it is receiving) and generates an arbitrary value called "load" and you can see that here, in this stock table.
However, some people alter these tables, because they may find that by changing VANOS, valvetronic, boost, etc, they will run into an instance where the DME load req and DME calculated load are wayyyyy off. The hard part to understand is this is kind of a bi-directional table. The DME is taking alllll the commanded values for alllll those variables I had previously mentioned and reverse looking up through this table. Then, it also takes allllllll those ACTUAL variables and uses this table as well. Lastly, but also probably most importantly, most people tend to adjust the last few rows in this table to prohibit "torque limiting" on the transmission. I do not suggest this.
The reason that "load" is used for these tables is due to how the DME handles powaaaaaaa.
The accelerator generates a "position" which is translated into a desired load value. This is what is controlled in the "Load Ceiling" table. If you're 100% on throttle, you get the rightmost value in that column. If you have pre-ignition, you move to the left in that table.
As such, that's sort of why you want a load value. If you're telling the engine "I'd like this much 'load'" then the DME says "OK lets try to do that. These are the values we should use. Let's see how it goes"
You could
essentially replace "Load" with "Throttle Percentage" as long as you scale that to your max load - For instance, my max load is 200%. This makes it easy, since I know that basically 100% load is half throttle. It's SORT of that easy, but there's some other fuckery in there (valvetronic and valve body). But to keep it simple, that's probably easier.
I think the second part of your comment is answered in the first part of this one. There are "two" loads, but they are only requested vs actual.
This is important to understand - if you have overboost (or any experience of too much air) then you will see a higher ACTUAL load. Requested load will stay where your foot puts it.
Quote:
Originally Posted by wheela
Okay guys, here's (hopefully) a basic question - can you please help me better understand how load(s) is calculated in these DME's? I've searched google, but haven't found any equations, or specific descriptions.
My current understanding of load is based on reviewing fueling and ignition tables on Mitsubishi ECU's (specifically 3g eclipses and EVO 7, 8, and 9). Since those tables are based on % load and rpm for the axes, I've assumed that load is just airflow expressed as a percentage of maximum airflow that the motor will consume at that rpm based on natural aspiration. So my naturally aspirated 3G had load up to 100% and the EVO's had load up to 170, or 220, or whatever (I can't remember), because the boost from the turbo could push airflow past the 100% point. So then for given RPM and %load (airflow) the ECU used the tables to determine what fueling and timing to use for that combination of %load (airflow) and rpm.
In the boost section of this thread, it's mentioned that some of the % load is also supplied by fueling, vanos, and ignition timing. What I'm not understanding, is how can fueling and ignition timing contribute to load, when fueling and ignition values are looked up from a table based on load (and rpm)? Is there some different kind of load? I can see how these would contribute to the torque value the DME calculates, but I'm not understanding how this fits my current understanding of what load is? Perhaps I'm not properly understanding what %load is in the first place?
I get that our DME's target a % load based on pedal inputs, and then make adjustments to throttle plate, vanos, valvetronic, etc. to try and hit the load target, and then continually adjust based on the actual load being achieved. But in MHD, it looks like there are at least two different loads that are measured against the load request %: "Load act. (%)" and "Load actual RAM". What are these two different loads?
Am I at least partially on the right track, or completely lost lol?
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