New (Again) to Nistune.....Type 2 question

[munibjudas]

Hello everyone. I am back after a 7 year hiatus from the world of Nistune. Just got it installed in my spare ECU. Car is 1995 R33 GTR, using R32 GTR ECU with Type 2 board.

I have a few questions, which I am hoping I can get clarity on, to ensure that I can still drive the car safely until I can muster up enough funds to get the car tuned.

1. Since I have LS2 coils and not the stock ones, should I change the dwell time on Nistune for them? And if yes, how do I do that? I do not see any settings to change the dwell on the coils.

2. The fuel map I loaded is for the ECU that I am using. I noticed that the numbers in the lower rtpm and load cells are 192, 195, 200, etc., and the rest of the cells have number around 4, 10, 9, 20, 40, etc.. I do not understand that map. Can someone help me understand why there is such a huge difference and what these numbers actually mean?

3. I am noticing that the car running lean-ish with the stock maps (16 under cruising conditions) and 13-14 under boost, which both seem to be a bit too high. How do I change them? Or should I?

4. Since I have two O2 sensors, can I see the voltage for both or does Nistune show an average of the two O2 sensors? Can I drive safely with the O2 sensors unplugged?

5. If I need to make the car run a little richer, what setting do I need to change a how? It has stock R34 GTR injectors (444cc), btw.

Thank you

[Matt]

1. LS2 coils you will need to look at the 'dwell time' guage (use the Display > knock panel to select and view it here) and then adjust the 'Dwell time' (vs battery voltage) table. Increasing the last half of this table will increase dwell time over the battery voltage range

2. Default load cell numbers should be:
8 12 16 20 24 28 32 36 40 44 48 56 64 72 80 88

These are the scales that the TP (load index) parameter is used to reference the maps. TP =MAF load/RPM * K constant

RPM tables have a raw ECU value x 50rpm = final RPM bands which goes up the left column

3. You should sort out any lean running issue firstly with the vehicle rather than fix in the ECU by retuning. Have a look at your trims (STFT / LTFT and see if they are around 0% trim) to start with

4. Nistune will show the voltage of each O2 sensor. You will need to perhaps enable O2 RHS if it is turned off when you connect to consult. If you reset your self learn trims, then you can unplug the O2 sensor. The ECU stores the trims from last time it was run

5. Same size injectors as R32/R33. Make sure they are all flowing properly. I am concerned some mechanical issue (fuel pump, injectors or otherwise may be responsible for the lean readout from all 6 cylinders). If one cylinder is running leaner than the others then you could have a potential disaster happening

[munibjudas]

1. LS2 coils you will need to look at the 'dwell time' guage (use the Display > knock panel to select and view it here) and then adjust the 'Dwell time' (vs battery voltage) table. Increasing the last half of this table will increase dwell time over the battery voltage range

2. Default load cell numbers should be:.....


..........If one cylinder is running leaner than the others then you could have a potential disaster happening

Thanks, Matt. I shall reply thus:

1. I will look into that table tomorrow morning during day time. Sun is almost down now.
2. I was not referring to the load cell numbers. I was referring to the values within the matrix. I am adding a snapshot of the fuel mixture correction (primary). If you see the values in the cells closer to lower load and lower rpm, they are ver very high - all cells are close to or around 195, while the rest of the map has much lower numbers. I wonder why that is and what it means.
3. I sorted out the leaning out issue to some degree - the car runs very lean when cold, and it took it around 20 minutes of driving to start behaving normally. The vacuum line to the fuel pressure regulator was not connected, and when I connected it, the fuel ratios came down. Still a bit lean as it is idling around 15.8 or so. It does come down to close to stoich when the O2 sensors are unplugged.
4. I am clueless as to how to enable the second O2 sensor or where to check if it is even showing the voltages at all. Could you please help me with this point?
5. Since the leaning out issue is a bit resolved, can I increase the fuel flow from the stock injectors at least for the last 2 cylinders to make it run better? Or if possible, can I change the overall setting to have more fuel dumped in? Please let me know how to do that, even if ti means all injectors would be putting out more fuel.

[Matt]

2. With the large cells (192+ cell value) those are O2 feedback cell indicators
Change your view from 'raw values' to 'filtered values' to make more sense

3. Okay good you found that. Would be interesting to see your fuel pressure at the moment

4. Display > Select consult registers

O2 (LHS) and O2 (RHS) should be enabled

5. It is only possible to increase for all cylinders (not individual cylinder trims) using K constant (or TIM on feature pack equipped boards)

[munibjudas]

Thank you, Matt. I see the filtered values now, and they do make more sense.

Two things: what are STFTs and LTFTs? Where are they and how do I view/edit them? I take it that they stand for Short Term and Long Tern Fuel Trim, but beyond that, I have no clue.

Since I do not have access to an actual fuel pressure gauge and do not know the fuel flow of each injector, I want to see if I can increase the flow for all of them to help with the running or decrease the latency. How do I go about doing that? I am going to check the plugs today and see how each cylinder has been running.

Does my Nistune have any safety features built into it, like the stock ECU? I remember my first Nistune in 2006-2007 had knock maps in it. I purchased this one recently from one of Nistune authorized dealers here in Canada. And by the way, what is a feature pack equipped board? How do I tell if I have one, or if I need one?

On the subject of MAF selection for the BNR32, do the two boxes at the bottom (GTR ECU and GTR MF) need to be checked off or left unchecked? In my case, from the .bin file I downloaded, only the GTR ECU box was checked and not the GTR MAF box. I am asking because it is showing only one MAF (LHS) voltage - 0.85v. I cannot even seem to select the second MAF in the display gauges.

Additionally, when I try to select the option to show all the gauges, it just makes a sound and then the gauges window doesnt come up.

I also got a weird error a few times, something to do with the ECU not having a PIN to start or something to that effect. The car is running as normal as it has been, with lean-ish idle (16.0-16.3). There is only one O2 sensor voltage that even shows up, unless I rev the engine, and then I see both O2 sensor voltages. STFT was at 13% and LTFT was 0%, but then a little later when I restarted the car, both STFT and LTFT were showing as 0%.

This is confusing me a lot - are the O2 sensors causing the lean condition or is it that both MAFs are not registering or connecting, or is it the fuel pressure?

[Matt]

Please refer to 'Software users manual' for STFT/LTFT gauges (consult view panel)

They display the ECU trims. You can adjust the overall fueling to get the trims aiming towards 0% (no trim)

Increasing TIM will increase fueling overall, but I recommend taking to a workshop to check fuel pressure. Adjusting in the ECU is not the right way to go about it

Nistune is the stock ECU (but retunable). The knock maps (low octane maps) are removed with feature pack code, but the ECU will still pull timing as per factory when knoc occours

Feature pack is covered here:
viewtopic.php?f=12&t=2874

Part number will end with 'F' in the ECU ID when you connect to the board (BNR32 = 05U6F)

For GTR ECU use the 'GTR ECU' tickbox ensabled

You need to tick box LHS and RHS MAF voltages in the Display > Consult registers tickbox selection to view the second guage. Make sure you are connected when showing the guages to change the values. It will disconnect when you click okay since the consult needs to reconnect again to display the guage (it is not automatic)

Errors with PIN are due to noisy connection (received invalid PIN response). Refer to 'communications and diagnostics' guide on the website (Support > General documentation) under the section with noisy consult data

STFT/LTFT should only be monitored when in closed loop (ie whilst cruising)

Likely mechanical issue (fuel pressure, plugs etc) since you have stock ECU and engine setup

[munibjudas]

Good morning, Matt.

On the issue of the MAF, when I connect, it does show me all the gauges I can check off, including the RHS MAF, but doesn't allow me to select it. I have tried and tried. I wonder why that is. Only the LHS MAF is checked off and its voltage shows up.

Is there any test I can do to see why that would be? I did disconnect and reconnect each MAF one at a time, to see if it impacted the car's idle and running, and in both cases, the car wanted to stall, which leads me to believe that both MAFs are connected to the ECU.

My ECU does not show the F suffix after it. Does it mean that it doesnt have the capability to adjust the TIM? I know I dont want to play around with the K constant, as that changes the whole map.

Should I just unplug both O2 sensors altogether and drive without them? Fuel economy is not the issue here....stable running car is, you know, as long as it is safe to do so.

I feel so ignorant about this whole thing...wish there was a way for me to know what to do after I disable the O2 sensors (unplug them), so that the ECU takes over the running of the car in open loop without issues. But the MAF thing is really stumping me.

[Matt]

[Following up via emails]

[munibjudas]

After changing the fuel pressure regulator, installing a fuel pressure gauge and changing the fuel filter, the fuel pressure did not climb and the leaning out issue persisted. What I was noticing was that the pressure would stay around 30 psi whether the vacuum line was connected to the FPR or not. Reluctantly, I decided to change the fuel pump. After 2 hours of back pain and bruised arms, I finally did it, and voila!! The fuel pressure climbed up to 43 psi as it should be. The AFR got better and the car ran great.

Next step, I also changed the injectors to 550 cc ones. Here is something funny. Both Denso and Sard make these injectors and I dont know which ones they are. However, Sard says to have the latency to 0.71-0.73 milliseconds, and Denso says to have it at 0.80-0.85 milliseconds. I tried the Sard ones, and the car leaned out significantly. With Denso setting (0.8 milliseconds latency), it runs better. Can they not make up their minds about what it needs to be?

I am unable to actually find a proper answer to this - what the hell is injector latency, and how does increasing or decreasing it affect the AFR? If latency is the time an injector stays closed, why does a lower value mean leaner afr? By that logic, the car should run leaner with higher latency than lower. Someone know the answer?

Also, do I need to adjust anything else other than the K constant for the bigger injectors? I havent changed anything else, and not sure if I need to.

Thanks.

[Matt]

Injector latency (or dead time) is the period of time it takes to open and close the injectors. Basically it is to compensate for the charge time to the coil (and electromagnet) which then in turn pushes the pin inside to open (and subsequently fuel flow through)

Standard 1:1 regulators should increase 1 PSI of fuel pressure for 1 PSI of boost to the FPR. So you should see an increase. Glad you managed to sort out the issue

Same injectors from different manufacturers but different specs? Best to check the datasheets for both

If you have feature pack in your ECU, I have added 'Total injection multiplier' to the standard Nissan ECU firmware which allows you to adjust injection time. If you dont have this then you have to adjust K constant instead (and rescale other tables to get the load to match up again in those tables)