I'm teaching myself about ecu operations (p28 specifically) and was wondering about the info transfer from closed loop, short term fuel trim to the fuel tables.

How is this accomplished?

At what time is the info considered permanent enough by the ECU to warrant it being put into the tables (hours, days, weeks, years)?

If you tuned for ~12.x a/f ratio, given enough time, would the ECU overwrite that and "retune" itself to ~14.x?

Or is it common practice to just run in open loop mode after tuning?

food for thought - Would it be possible to tap into the stock ECU long term fuel trim process and modify the fuel tables. Because wouldn't that, in effect, eliminate the need for chipping? (Neglecting ignition map concerns)

 

Got a little tease of info from Hondata:

"If, at part throttle the ECU sees the air fuel ratio is too rich or lean the ECU makes immediate (short term) corrections. Over time those corrections are learned and transferred to a long term trim value that is applied all the time."

So I would guess that the LTFT (long term fuel trim) value is a constant that is multiplied into the fuel tables and doesn't actually change the fuel table values. Anyone have experience in this? Anyone???

 

try http://www.pgm-efi.org or something like that