Help with diagnosing fuel cut

[KidNeko]

Hi All!

Finally finding time to rack up some practical experience with NIStuning, so please bear with me if I'm being too persistent on trying to understand some NOOB stuff.

I'm tuning my R34 GTT, with basic intake & exhaust mods, Mamba 2971 3" turbo, stock injectors and MAF.
Wanted to get a good understanding of the NIStune before dropping in 550cc Sards and a R35 MAF.

SO here's the thing, I'm currently hitting a cut at full? boost around 4500rpm and I'm looking for some enlightenment.

Attached are a couple of pulls I did on 2nd and 3rd gear.
As you will see, the car will boost up to a point and will hit a cut, looses power and goes into coasting mode.
Doesn't recover until throttle is lifted.

I know I'm on the verge of the TP and/or boost cut limit but not quite over.
Is the ECU cutting because I'm too close? Or is it something else all together?

Both pulls are done on base maps with the following adjustments:
240818_01: Load(TP)cut increased to 182 at 3200 & 3600 rpm
240818_02: K constant reduced by x0.88, auto TIM

[Matt]

Thanks for the log files. Are you able to post also the current tune you are using?

[KidNeko]

Thanks Matt! Certainly.

I understand that I could try to increase the load and boost cut tables, or increase their counters to see if the problem goes away, but I would like to figure out the cause instead of just switching off stuff.

On a side note:
Am I correct to conclude that load/boost cuts will NOT recover unless the throttle is lifted, even if the values drops below the recover limit?

And does the knock sensors affect the tune? I'm occasionally getting a knock sensor 34 error code, was wondering if it needs addressing.

[Matt]

Pic attached shows the cut from your log file.

Boost pressure sensor 4.66v and 4000-4400rpm boot cut table 4.560V (4560mv) so you have hit this. It starts counting once it reaches the value and then does the cut

So you can increase the values in this table (18psi = 5.12V) until you hit the max

Over 18psi you will get a boost sensor fault code. You can increase the boost sensor max value to avoid that code, and also increase the counter (boot max) to 255 (maximum) to avoid a cut over this boost level

The TP limit tables and counter are used if the boost sensor is fault or not available

Knock sensor issues will retard timing in the timing map

[KidNeko]

Thanks Matt

I'll try to fiddle around with the cut tables & counters

The thing I'm not understanding is, looking at the runs on my 240818_02 file and checking against the cut tables, I don't seem to have hit the limits but the cut still happened (Attached screen shots). Am I missing something

What do the cut counters actually count?
And is the TP cut table not in effect when the boost cut table is active on the NEO ECU? Or do they work simultaneously?

[Matt]

Neither image you posted shows a 'cut'

When you get a cut you will get a sudden drop in injection time. We are not seeing this here. What we are seeing is a short (first image) or medium (second image) drop in everything. Check to see if it is leaning out. Could be other factors, like AFRs going lean or restricted exhaust / airflow

Something else is going on. Can you get AFRs to link into the laptop and display against the consult values?

[Matt]

What do the cut counters actually count?
And is the TP cut table not in effect when the boost cut table is active on the NEO ECU? Or do they work simultaneously?

Cut counters are not documented by Nissan but they appear to be time based, depending how long it has been since the voltage exceeded the boost table

If using boost cut, I have not seen evidence of TP cut being used (valid boost signal and no fault codes)