How do I go about tuning calc load max on an NA engine, what will it do, I've only been able to find people with boosted engines tuning this stuff

 

The load max is an odd thing to me. Best guess is that it exists to prevent you from reaching a load point that is beyond anything mapped on your fuel/spark tables. If you do that, I'm almost certain that fueling defaults to stoich. That is to say, it will try for stoich. I don't know what it will do on timing.

However, this "safety" feature just makes you go lean anyhow.

I would just make sure you have a "safe" load point mapped at a load 20-30% higher than you have ever seen in your fuel and ignition tables. You can changes the column headers value if need be, it does work.

Then set the just make the load caps a bit below that, and hopefully your ecu will never see a point where it doesn't know how to calculate fueling/spark.

Note: unless you recalibrate the upper end of your MAF scale, or have a very strong NA, none of this should be an issue.

 

/\ interestingly the stock Mazda maps seem have max. calc. load set at the same level as the what a stock NA car would normally see .So when you log at WOT - all calc. loads are 100% pretty much as soon as you floor the throttle .

Why that is done is somewhat of a mystery to me as i see scope for incorrect fuel/timing once actual load exceeds this.
For FI tuning I have my max. calc load set for 2.0 from about 2500 rpm and load never reaches that level . This seems to make more sense as you want some headroom should you raise the boost .

 

Maybe this feature exists simply to break your engine if you try to mod it. :/ Of course, then they also ought to have it generate freeze frame data when you hit the load cap.

If that was Mazda's only goal though, I would have expected them to implement the same kind of lockout that Cobb does to prevent reverse-engineering of the ECU. It is a built-in feature of the Renesas CPU, and though there is a way around it, Mazda would not have been aware of it at the time.

 

Do NA Renny's ever see more than 100% VE?

 

yes

 

So after doing some logging with ScanXL Pro and the Cobb, I realized the cap is just getting in the way, i've since raised all of my Load Max values to 1.5 which is more then my N/A sees... But yeah I was hitting the cap and it kept cutting fuel at high loads! O_O BS!

 

Yes, but 110 -115% is probably sufficient and will allow for more tuning cell detail than a grossly excessive number

 

well I can set the load max to a stupid high number then tune the ve table and what not based on what load my engine actually produces
edit: DERP! of course, those tables all work off of calculated load, not actual load.... but raising the calc. load max wont change the calculated load, just allow it more freedom? When you say allow for more cell detail, which tables do you mean, the only thing the calc load max should effect is where the cut off for the calc load formula is ie. 1.00 and even if it could go higher it will stop there..

 

Yeah, nearly as I can tell the max you set has no impact on how load is calculated, it just stops the ecu from looking at load points beyond that point.

However, whatever you set it to, you probably do want fuel/spark mapped at or above that point. The ecu seems pretty good at interpolation though. If you set a rich fuel cell at 150 load, and an error causes load to be calculated too high, the fueling would go too rich, which seems better than going lean, as it is designed.

 

good to know :P thx, I use an excel sheet to find the average load based on throttle position and rpm, so that I have a good idea of where to set my limits with the rest of my tables involving load

 

You guys don't understand hot how it actually works.

Here's a clue:

Instead of thinking of it as a "do not cross" line drawn on the page, imagine that it is the actual edge of the paper.
It is an analog to Einsteinian space.

 

I get that, it SETS the "edge of the paper" for the calculated load based on whatever conditions... I worded it poorly though :P I could set it to 10 and it won't change the value for calculated load... as long as my N/A 13B doesn't decided to go above 10 somehow! O_O LOL

Thanks though

Edit: PS nice avatar! :P

 

No, you don't get it or you wouldn't have made the emboldened statement above.

 

So before I go and make an a$$ of myself, what did I not get? with all my logging I have never seen my engine go higher then 1.2 calculated load... :S my understanding was that if I set the load max to 1, then in all the formulas involving calculated load that variable could never go higher the 1. So if you set load max to a number higher then what your engine is capable of and set all the load variables to a reasonable number for your engine (*0.06 - 1.3 for example*) then load max is not being used as a limiter.. Or rather its impossible to reach it

Sorry if I seem arrogant, this is how I actually believe it works and I would appreciate your insight if I'm wrong!

edit: fixed my curse word with something more appropriate for a public forum! :P

Edit: perhaps I misunderstood what load is... that would seem to make sense, but was I right in how load max relates to calc load?

 

In other words - if you exceed the max load all values default to the value in the max load cels ? IE the value at the edge of the paper .

 

I'm pretty sure I understand that, so that just leaves me to ask what the h3ll load is, I thought it was something to do with grams of air per cycle...

Thanks for your time by the way!

 

NO!

The "exceeded" value is virtual. The "max" value isn't a max value.

There is no defaulting going on.

 

 

Lordy...

 

MazdaManiac, this is such a simple issue; your obscurantism must be intentional.

 

I didn't say it was "easy" and failing to provide, at length, exact explanations here should not be construed as "obscurantism".

I figured it out, so can you.

I was merely pointing out that you got it wrong.

Do as you wish.

 

Your mission in life ?

 

Absolutely!

We are all on a path of discovery here. I think it would be a shame to let someone make the same mistakes or travel down the wrong path for long as I already have.
But it would be equally a shame to deny someone the process of discovery.

So, I just try to keep the discussion going in the right direction without giving up the final result.

This has the added benefit of possibly adding additional enlightenment on the subject as people have different perspectives on the process.

It is just a twist on the old "give a fish/teach to fish" thing, only I am simply keeping you pointed in the direction of the lake and assuring you that there are indeed fish to be had.

 

Damn fish... I think your pointing at the ocean and saying grab the one that no ones knows about yet with big teeth and scary eyes... Not only have I searched the forum and rx7club but I searched the net and found some very useless tidbits about calc load max, which as far as I can tell is a mazda thing, so I'm going to go with my favorite method here, K.I.S.S., keep it simple stupid. Just tell me if this is a decent comparison

Calc. Load max = 1.00 across the board (*excluding the Baro and IAT*)
if calc.load (*for whatever table*) > 1.00
then calc.load = 1.00 (*so in the formulas calc. load can't go above calc load max*)

it kind of sets a range of valid values, in this case calculated load can be anything less then 1.00 (*not to say the engine isnt capable of more*)
now I don't know how the engine reacts to reaching the limits of calculated load (*because of calc load max*) when it should be higher then 1.00 Edit:as set in the example.

I noticed on particularly hot days my engine would start to sputter right around 8000-9000 rpm in third gear or higher and lose power, but after I raised the calc load max (*had my test flash ready :P*) I was able to get rid of my sputtering problems as has been the case since, and its only been getting hotter.

I suspected it was the calc load max because I was using my logs to find at what rpm I was reaching loads that matched the limits and sure enough it was right where the sputtering was, why it sputtered I still can't figure out (*cut fuel?, timing?, something? O_O*)