MAT Correction
 

It seems like I'm consistently running lean (or at least my ego corrections are running high) when it's warm out. The VE analyzer just wants to keep adding more fuel the warmed it gets, and tries to pull it back out the next cool day. It seems like I need to mess with the MAT correction table, but the Megamanual has next to no info on how it works:
http://www.msextra.com/doc/ms2extra/...ion.htm#matcor

I'm trying to find some info to get started with, but haven't been able to find a good example so far. If I'm running lean around 120 degrees should I be using a positive or negative number in the correction table? Any idea what actual effect a number like 10% has on the pulse width values?

Do a google search of "what is mat correction for". I did it today my self as i was not sure how to set it but there are a few links that go to MSextra.com. They will explain how it works.

change mat correction value to 50 initially.

that will work pretty well for other than really hot starts at idle. then you gotta add (positive) values to the MAT correction table. but be careful not to add too much- i added a bunch to get my idle spot on, it ended up making all other conditions/WOT too rich, ugh

It's the internal ideal gas law code. I've already had it up with the developers about it.

thy scoff at the idea that this could happen because it violates the law.

I love MS, but it bugs me that the devs are so close-minded about stuff.

Similar with the PID code, Jason does PID for a living, yet because Ken can get it to work on his car there's nothing wrong with it.

I wish I was bright enough to be able to code.

Get up with that Mario guy over on MSextra. He's putting out modified versions of the code. He sounds pretty open minded about the code ideas.

Honestly, the PID works great for me. I've had no issues tuining boost, idle and EGO.

I'm sure if Jason wanted to contribute, would write code and sign it over to Ken royality free, they'd be more than willing to take a serious look at it. I can understand that Ken and James want to use their own code, it's their baby. They did take a bunch of suggestions and implement changes done by this Mario fellow, I'm pretty sure they discussed royalities offline.

And to be fair to Ken, he agrees that while the ideal gas law cannot be disproven, there are other factors in play (not just heatsoak) that aren't being factored in.


The best way to handle the ideal gas law code at the moment is to alter the MAT correctoins table in a way that reduces the coded corrections. Setting the MAT corrections value to 50% cuts the enrichments by half, and you can fine tune the rest with the table.

Way ahead of you...

sorry for bringing back such an old thread but im having a similar issue. get my tune dialed in perfectly... outside temp changes and my afrs turn into crap.

im running ms1v3.0 with extra029y4 on a 94 BP+T using miata cas and toyota cops.

are you talking about cutting the values in the offset side of the table in half or is there an actual MAT corrections value box that needs to be changed? im not really a computer guy and im having a hard time wrapping my head around this.

it cuts the coded ideal gas law corrections, that wreek havok, in half.

Made up numbers: So instead of a MAT of 100°F causing the MS to pull 5% of fuel, it only pulls 2.5% of fuel--and I still find that too aggresive imho.

What did you end up settling on? I have MAJOR problems with hot restarts after the car comes off track.

how close is your AIT sensor to the rad?

It's about 1-2" off the throttle body attached to some plastic piping.


e: it does come out of the driver's side of the pipe so it can catch radiant heat from the radiator. Not sure if it matters because the whole engine bay is completely heat soaked after a session.

oh it matters. The best way to defeating this is moving the AIT outside the engine bay, just post IC.

tuning your MAT corrections curve will solve it completely, but it's a band-aid solution that can cause other issues.

I've been able to introduce a few changes where needed in code... so what's wrong and what needs fixing???

in MSI the MAT corrections were able to decay out after a certain RPM. So you could use them to combat heatsoak related starting issues.

Before I moved my AIT sensor to my IC endtank, I could see the AIT jump from 70°F right after to stopping the car and climb to 90, even 100°F, within a few minutes.

Since the ideal gas law code is VERY aggresive, the car runs lean as crap when you start it back up...sometimes barely able to catch/idle.

You can solve this by tuning the MAT corrections table, where you pretty much end up negating the ideal gas law temp corrections.

The only solution I was able to work out with Ken and James was for them to allow me to disable and AIT corrections during ASE. I didn't like to solution. The problem is, you really need to start getting real airflow across the sensor in order for the temperatures to drop back down, this means more than idling. Typically ASE is only a few seconds, so it's not enough time.

I moved my AIT sensor to my IC and it's been much better to protect it against heatsoak, but you still see a delta after the car has been shut off, just not as much.

So, if I use the MAT corrections to add back in fuel when the temperature climbs past 85°F (I think that's where the first 1% is removed), and since I can't have the MAT corrections table decay as the RPMs increase, if I enter boost and actually see temperatures well over 100°F, then my fueling gets screwed up--I'm fighting the ideal code, when in this case would probably would well.

This is especially apparent on the dyno when the intake temps are greater than normal.

Ken and James pretty much refused my idea of adding in a RPM point where the MAT corrections were disabled, they were open to the idea of a MAP trigger point, but it was never implemented. I made the case that the MSI already has this, but they never wanted to add the same feature to MSII or MSIII. Reverant went ahead and already custom coded this cut-off point for his MSIIs, and it was actually one of the reasons he didn't want to jump on the MSIII bandwagon until the code was available for open source, to fix this specific issue.

i still dont understand how i can change the mat corrections to 50%

Then you have bigger problems.

But I probably wouldn't start by opening up the software and looking at the dropdown where the MAT Corrections parameters reside. I certainally then wouldn't see one labled "MAT Correction value." And I wouldn't open that dialouge window and see that I can input a value from 50-100% to change the scaling of the ideal gas air density corrections.

What about doing in hardware what you can't do in software? Use a space MS output to trigger a circuit to switch from an ambient air sensor to an in-intake sensor?

ive been looking in tunerstudio advanced>coolant related air density,all there is is the table. no corrections%, i went through the settings and changed it to

air density=corrected
corrections based on= iat corrected
but i dont see mat corrections %

ive been looking through it but cant seem to find what you describe. if you could be more specific where to find it... im retarded but i am trying to learn.