mine didn't zero out either. and my original numbers were also a little higher than tephra's

 

Why would it 0 out the LTFT? You'll just no longer see the LTFT affecting WOT operation... I'm fairly certain this is working on mine right now.

This mod does NOT disable the LTFT during idle or cruise. You do that by manipulating other maps, but that's not the topic of this thread.

 

oh i don't know......

 

log MUT50 guys... that is the copy of the current LTFT in affect...

bryan - can you send me the ROM in question? I'll double check it

 

log MUT50 guys... that is the copy of the current LTFT in affect...

bryan - can you send me the ROM in question? I'll double check it

 

bryan what rom id does that one have? mine is 015

 

Is there a formula for that fuel trim or is it the same as all the other ones?

 

it's a copy - so same formula

and when I say log MUT50 - I mean grab the 4 bytes @ MUT50 (0x0080XXYY) and log that (0x0080XXYY)

 

Thanks!

 

Ok did this on a GSR today. It didn't zero out the LT trims, however I did notice that the LTFT had no effect on Open Loop fueling anymore.

Awesome.

I guess the LTFT in evoscan is different than the addresses you are logging Tephra?

Thanks again for finding this.

- Bryan

 

it wont zero out the trims.

it will force the high trim to be used, which should be zero

addresses should be the same.

did you try logging MUT50? you can see it transition from low -> mid -> high (it will be the same %'s anyways)

 

I've finally gotten my LTFT's to settle down and have a consistant +-1 LTFT for the most part. Currently I have the "LTFT not effecting WOT" code in place where the crossover is about 600 Hz and everything seems to be running extremely well. That's about double the flowrate of setting it for 300 Hz so the partial boost will still be effected by the LTFT's. Not sure it makes a huge difference but I figured I would test it out and so far the drivability seems to be good with consistant 11.6 AFR's at WOT. I'll tune slightly leaner and see how clean I can keep the rear bumper.

 

Here is how it will look when you log LTFT HIGH.

FROM: 52680020



How to log MAF Hz




Notice that LTFT HIGH goes to 0%




Now with MAF Hz logged/

 

Dave and acamus, nice job on finding this. As part of my fuel pulse width disassembly, I just finished determining the same thing for the Evo 7/8/9. I'm borrowing your table for my Evo 7-9 notes. :-)

Allowing the LTFT mid to affect open loop fueling might not be such a bad thing, but what could be annoying is the step change in fueling caused by the transition from mid-to-high trim. For the Evo 7-9, the 1-byte MAF Hz variable is used, so the mid-to-high crossover value can be no higher than 1600 Hz. For the stock crossover setting of 1597 Hz, high HP cars will always experience a fueling transition when crossing 1597 Hz. One way to deal with this might be to set the mid-to-high crossover to around 200 Hz so that there are three active fuel trims. This might allow better injector tuning and would stop the step change in fueling at high Hz.

 

The table was actually stolen from someone in CT9A land - I forget who

But yes I thought about running 3 legitimate LTFT's, but really without exhaustive testing it's hard to know exactly how to set it all up.

I found that the mid trim varied so much that the stock setup really wasn't ideal. So "disabling" it seemed like the best option. So far my WOT AFR's have been much more predictable.

I settled on 343/350, since this is about 140-160 load (at 2500rpm) .

Same 1byte MAFHz setup on the X btw...