Hi All,

Just a quick announcement to say I think I have worked out how to disable the trims affecting WOT fueling.

Thanks to Acamus for some seriously hard core disassembling

Ok we all know how the Fuel Trims work, basically MAFHz bins, so Low/Medium/High

Usually High isn't used, here is why:



Left is stock, Right is my modified one

So the High FT won't be used unless the MAFHz goes above 1593.75, which won't really happen on stock turbo.

So I have modified the High bin so it's lower. And thus gets used.

Now here's the best part, because of how the STFT works, the High FT should really NEVER get populated with anything OTHER than 0%.

I have done a log and you can see the High FT being used in the fueling calculations, and you can also see it being set to 0%, so now I don't have my Cruise (Med) Trim affecting WOT.

That's for 53040010, but also should work for 526800XX - If your values for above don't look very similar to mine then something's wrong.

If your interested in logging trims then find the MUT_TABLE - then you have the addresses you need to log:

MUT0F = STFT
MUT0C = LTFT_Low (Usually Idle)
MUT0D = LTFT_Medium (Usual Cruise)
MUT0E = LTFT_High (Usually not used, but that's what this MOD is all about)
MUT50 = Copy of the trim currently in affect

DISCLAIMER: DO NOT USE THIS UNLESS YOU HAVE A WIDEBAND AND LOG YOUR ECU

Cheers
D.

 

That's awesome!!!

Thank you for this...

I finally got my cruise trims -1.01 on average to 0. But this will make your life so much easier. I will let you know how it works.

EDIT:

THIS IS HOW IT LOOKS FROM 52680020.ROM from a 2008 GSR.



IS there a need to edit the top two values to what you have posted?

 

Awesome. Thanks for the new info!

 

Awesome find!

Are the MAF values really in Hz still? I thought that was indicative of a Karman vortex air meter, which we don't have any more... at least I don't believe. I thought it was a hot wire MAF now, 1-5 V or whatever.

 

Excellent work!
I used the address for 53040007 and the std values match your example exactly.
Should i proceed to adjustments?
300 Hz equals with what load approx?
My congrats!

 

Awesome detective work there Tephra! I'll test these tonight and report back, the difference between blowing unburnt fuel and being relatively clean seems to be somewhere between 11.5 and 12.0 AFR's on my particular car, and the 3-5% LTFT swings from day to day were driving me nuts lately. The car would haul **** and be mostly smoke free, then after it adjusted itself the car wouldn't pull quite as hard and you could visibly see a smokescreen behind with richer AFR's. This will make the car MUCH more consistant!

 

a BIG thanks to you and Acamus. I am getting tuned friday and having this in place prior will be a huge benefit.

 

Awesome Tephra! If the same can be done for WOT timing then it would be a perfect world

 

The addresses seem to match up to the JDM all models including the 2009 & 2010 models. A big thanx to Tephra & Acamus!

 

280-300 MAFHz is about 100 load.

 

Can someone recap this for me? My understanding is:

- fueling from day to day (not pull to pull) would vary significantly on evo x's (by how much?)
- the cause was determined to be a varying mid trim
- earlier evos trims would not effect wot but evo x's it does
- tephra and acamus figure out a way to change the cut point from mid-high
- therefore you are in high trim mode during wot, and thus wot is not effected by the mid trim
- the high trim is always 0% (why?)

 

possibly dumb question, but can I add the same values for the IX? Im assuming, yes.

great job acamus and tephra!

 

yes there is a IX equiv, the XML is actually stolen from the CT9A forum, just the address is different.

crcain:

As I tried to explain when in closed loop the STFT drops to 0% (or 100% depending on your logger)

Since the LTFT are just averages of the STFT for various MAFHz bins it is logical that when STFT is 0% then the LTFT average will be 0% as well.

 

Actually pull to pull was possible, if I had just warmed up the car sometimes it would be stable, other times it would start shifting the LTFT from -2 over to +3 and run about 5% richer than expected. So my 11.5 AFR would drop to around 11.0 AFR and it would be smokescreen city. Then If I got on a different road with a 30 mph speed limit and the LTFT's started adjusting again it could swing back again. If I got on power entering the expressway then out of the blue the trims would be back to the way they were. I've logged it in the same drive several times and it was EVIL.

Another issue was that at higher airflows, if I was currently at +5 LTFT and it surpassed that higher hz reading at 6000-6500 rpm's with a larger turbo, out of the blue the 11.5 AFR that I tuned for might lean out to 12.0 AFR unexpectedly when it changed from mid to high trims.

Like Tehpra said, the high trims that we are kicking in earlier now are going to average 0% since the running average of the STFT during WOT should always be 0%. I love this!

 

You should be able to see the trim being used by logging MUT50 - same formula as the other trims...

You can log MAFHz with MUT1A (x*6.25) and then you should be able to see when the STFT drops to 0% (closed loop)