Just a random comment really... I noticed the other day that the cruise long term fuel trim seems to make adjustments every 4 minutes. Anyone else notice this or have any comments on it?

 

If you are using evoscan, with one of the recent versions he switched the short and long term fuel trims. I have posted this issue a while ago. I am not sure if this was by design or a mistake. Mitsulogger as the trims the way evoscan used to be.

 

I'm using ECUedit. However, I'm looking at the three stock MUT fuel trim values. One stays at zero all the time, one changes at idle and the other changes during cruise. I didn't think MUT gave a short term fuel trim value? If so, what's the Request ID?

 

just in case,

the "zero all the time" is your long term trim, I suppose eventually it will move

then there is short term at idle
and mid term trim at cruise.
they move at odd times as though some variable has been knocked over, but normally during an extended period of whatever type driving you are doing.

during a cold start they will try to "fix" the afr and then correct itself after the car has warmed up, so the trims move, in a small range, regardless of how perfect you have them set.

 

Request ID for fuel trim:

Short = "0C"

Mid= "0D"

Long = "0E"

 

0C = LTFT Lo
0D = LTFT Mid
0E = LTFT High
0F = STFT

LTFT is long term fuel trims. STFT is short term fuel trim, sometimes called O2 feedback.


Eric

 

What is the difference between the Lo, Mid, and High LTFTs? Is it different load regimes? Different RPM regimes?

 

I haven't done the disassembly myself, but I believe it is different airflow ranges. The cutoffs make the Low for idle and the mid for normal cruising. The High would be very high airflow cruising, which wouldn't normally be met during daily driving.

Perhaps someone who has disassembled the routines can tell us for sure.


Eric

 

Maybe I'll take a look myself today. Just have to go get my PC from work.

 

It seems to be different airflow ranges as mentioned above.