S14 SR20DET holding on to closed loop??!?!?!

Discussions concerning the M7790 cpu

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gsportcars
 

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Re: S14 SR20DET holding on to closed loop??!?!?!

Post by gsportcars »

Thanks Matt.
I'll try and run full time open loop for now and I'll offer the owner the option of a nistune board to get it sorted 100%.


EDIT.....

I switch the o2 flags on in all the cells and deselected the o2 feedback flag as mentioned earlier in this thread. I can confirm this works for staying in open loop.
STATUS
 

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Re: S14 SR20DET holding on to closed loop??!?!?!

Post by STATUS »

this is probably my favorite FP feature lol, it makes our life so much easier!! screw launch control this is actually useful :P
Matt
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Re: S14 SR20DET holding on to closed loop??!?!?!

Post by Matt »

It ended up becoming a necessity. Resolves so many issues with the one parameter

FYI for interests sake I compared the S15 MT and AT models. One uses 480CC and the other 370CC injectors, otherwise pretty similar tune. Nissan rescales ALL the TP tables and parameters to compensate for the K constant adjustment require for the difference of injectors. Just using the TIM parameter negates the need to do this level of change. Never could work out why Nissan did not add a load independent injection adjustment to their ECUs (until NEO ECUs)
Matt
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Re: S14 SR20DET holding on to closed loop??!?!?!

Post by Matt »

More work was done with investigation for K11, and additional parameters have been added to 1.2.97

http://www.nistune.com/mantis/view.php?id=27

Updated Mapping Guide:

Closed Loop (RAM map) RPM/Load Scales
Closed loop trimming works by adjusting both STFT (short term FTS) and LTFT (long term FTL) trims within the O2
feedback area (aqua highlighted area below).

Outside the closed loop area, FTS will reset to 0% and the ECU will hold onto the values within the long term trim,
until outside the closed loop TP (load) and RPM ranges.

Internal trimming map
An internal 8 x 8 cell map held in memory (RAM) of the ECU is updated with narrowband closed loop trims whilst in
closed loop. If adjusting K constant, the tuner map find that the area being held onto in closed loop continues outside
the normal highlighted (flagged) area. Adjust the load and RPM scales of the closed loop RAM tables to adjust for differences with K constant (where
available for your ECU)
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