xhomm02

I found something really strange with my EVO X:

When I log my fuel trims during a long cruise (like 100km), I see LTFT in -0,25 to -3% range.

When I sum LTFT + STFT (to get total correction) in all closed loop rows and then I calculate average from all these total corrections, they are POSITIVE cca +3%!!!

How is it possible that average LTFT and average total trim are on opposite sides of zero?

I know that ECU calculates LTFT each few minutes - is the calculate value average STFT from the last period?

Thank you,
Martin.

tephra

iTrader: (6)

What do you mean "closed loop rows"?

LTFT's are first "binned" by MAF_Hz's

So basically the ECU has 3 bins, low, mid, high.

When the MAFHz crosses pre-configured barriers the ECU activates a certain LTFT.

Now every few minutes the ECU looks at the current STFT and says - "I am adding 5% fuel, I *should* really add this 5% to the LTFT that i'm currently on"

Since LTFT affects fueling BEFORE the STFT is read/calculated you should realise that STFT is based UPON the LTFT. ie if your LTFT is +5% and your STFT is +5% (average) then eventually the ECU will set the LTFT to +10% (or near enough)

xhomm02

"closed loop rows" - I mean I used in Excel only those rows of my log that were logged while the engine ran in closed loop

What I do not understand from my log is that when I calculate average from all trims, I get a little bit positive value (like +3%), but all my LTFTs during cruise are a little bit negative.

xhomm02

So basically the ECU has 3 bins, low, mid, high.


I only see 2 diffrent number - for idle (and VERY low load) and for the rest

tephra

iTrader: (6)

don't average out all the trims.

they aren't long -> longer -> even longer averages. they are MAFHz's bins..

xhomm02

It looks like we do not understand each other.

I wonder why average of all trims is positive, while ALL LTFTs are negative numbers.

tephra

iTrader: (6)

post up a log and highlight what u mean