Nistune Forums

Hi all

I'm just starting out with nistune for the first time, previously a lot of experience with power fc, and setup one track gtr with haltech.
Something I have not done any of is street cars, and this is my first time doing an actual street tune and considering closed loop operation.
Weirdly, I have been scanning the forum for info and can't find much about the standard rb26 and tuning it mildly. Everything is aiming at getting K and TIM right after AFM and Injector swaps and starting from scratch with the fuel map.

1st Question:
My GTR has std afm and injectors, with bit bigger turbos etc. In this situation the process in the manual seems to be to leave k alone. I am wondering if it is still worth looking at K because of the turbo swap. Do cam gears potentially affect k? I understand if I put the boost up enough I will probably run off the map and at that point would need to move k and start over.

2nd Question:
Now this is where I have next to no experience!
In the closed loop areas, say the bottom left 6x6 of the fuel map, is it better to leave the values stockish or set them all to aim for 14.7? I notice stock fuel values down there are a bit rich and lean in certain spots. Is that slight richness good for transients and then if you stay in that cell the o2 will sort it out or is it better to aim for 14.7 instead. I notice on the autotune section of the software manual they have it set up in big blocks, a bit more like I am used to with the FC and that the bottom left is all 14.7

3rd question:
Maf imbalance. It seems my turbos read quite differently. Swapped AFM around and it was pretty similar so reasonably confident it is mechanical. Will balancing the wastegate actuators properly help with this or is it just the way it is? Hoping to confirm before I change a shedload of the maps to make sure I don't need to start over.

So far I have done more research and logging than tuning, I do really like the software and expect it to do well. Any advice on the above is much appreciated.

Thanks

1st Question:

My GTR has std afm and injectors, with bit bigger turbos etc. In this situation the process in the manual seems to be to leave k alone. I am wondering if it is still worth looking at K because of the turbo swap. Do cam gears potentially affect k? I understand if I put the boost up enough I will probably run off the map and at that point would need to move k and start over.

You may not need to touch K. There is always the option of just tweaking the last load (TP) scales if you wanted to add extra resolution at the top. Depends if you are happy with the fuel and timing at the last column, depending where you hit in on full boost

K is usually adjusted when MAF is changed over, and rather than re-adjust the load scales, we readjust the load referencing itself

2nd Question:

Now this is where I have next to no experience!
In the closed loop areas, say the bottom left 6x6 of the fuel map, is it better to leave the values stockish or set them all to aim for 14.7? I notice stock fuel values down there are a bit rich and lean in certain spots.

Let me make this clear for everyone - the ECU has no concept of real world AFRs! It is a calculator. It knows how to calculate a base fuel mixture from the MAF, and then trim it with the values in the fuel map (and the trims from the O2 sensor)

The signal from the narrowband O2 sensor which reads higher/lower than lambda and then adjust mixtures to reach lambda

The Nissan ECU is not like aftermarket units with VE maps and target AFRs. Those AFRs numbers in the fuel map are only available in 'expert' mode for a reason. For tuners who plan to target these numbers, and tweak VQ/K to achieve them (not my recommended method, but it is still there)

The ECU does not know actual AFRs... adjust the fuel map (filtered values) to what you need (on the wideband to view actual AFRs) remembering that the lower 6x6 area will be references outside closed loop (for example acceleration)

Unsure on the 3rd question

Sorry Matt, maybe second question could have been clearer.

I'm basically asking if the low load areas are usually made flat zeros (with TIM adjusted if necessary) or if they need to be a bit everywhere like they are factory (0's, 1's, 2's, 3's looking a bit rough). Is my target real Afr in these areas 14.7:1 and it is achieving that through these numbers, or is it slightly richer if you pass through the cell momentarily but if you cruise there it will trim towards 14.7..

I'm probably thinking too much into it.

I was wondering if stretching out last few load columns is still viable with fp so glad that will be ok. Currently just hits last column at 0.8 bar so not a huge edit to get it where I need to.

Thanks for your help

See how you go with a run through the cells as they currently are from factory and the readings the wideband shows. Nissan will normally richen up the map from factory for safety/warranty reasons

I would imagine in that area they would not need they need changing (much) from factory. Normally target would be around 14.7:1 through those cells then starting to richen up on boost

Excellent thanks again