Closed loop strategy

[EFhatch]

Hi there, last cars i tuned i found something wrong or just different about closed loop working and id like to ask it for to know more about how exactly works closed loop when it's actived once car is tuned in open loop.

What i noticed is afr change a lot once car is tuned in open loop, even when it's close to 1 lambda (14.7afr), when close loop is activated suddenly it goes too lean and short trim add +25%, i even tried to compensate it with fuel compensation in close loop but nothing change, just i have to enrich fuel table values for to get close to 1 lambda, my question is, doesnt it closed loop adjustmaent is based on fuel values? i means, if you are in open loop and get, let say 14.5afr, then you active close loopp, shoulnt you get only around 1% or less in short trim?

Thanks in advance.

W.R.

[Spunkster]

Without the calibration and datalog showing the issue it is hard to speculate on what the issue might be.

[EFhatch]

Hi, thanks for your reply, havent cal in hand, anyway do you could explain please how exactly works close loop once it's activate please? and how it affect to fuel tables once it's tuned in open loop? thank you!

W.R

[Spunkster]

Have you read the info in the help file at: https://hondata.com/help/smanager/close ... sub=closed

[EFhatch]

Hi, sure! i tuned +100 cars on hondata. last ones cars ive been using your close loop that looks works ok, mainly for smoke test here in Europe. even noticed if im right long trim has memory, i means, it save last one when key off and key on., rate of change works good too!. just id like to understand why that big changes once you tune everything in open loop and then when change to close loop, it appears map is untuned and fuel trims take to compensate even +25% when just should do corrections around 1 or 2% as max. Tomorrow i have to put another car on hub dyno again , runing s300 too. Thanks

W.R.

[DaX]

I always completely de-power the computer before tuning to re-set the long term fuel trim (LTFT) to zero. Then, during tuning, don't allow the ECU to make any fueling correction to LTFT. This ensures zero stays zero.