Nistune Maps users guide

[Matt]

This is an update from my original 'diagnostic' document

http://www.nistune.com/docs/NIStune_Mapping_Guide.pdf

I've gone over HCR32 for a quite a number of hours tonight with the hardware maptracer and documented the tables which need a bit more explanation. HCR32 has more tables added and these will be available shortly. Next ECU targeted is the BNR32 and boost tables to go under the scope

I'll gradually add more ECU specific tables as I go but this is definately a good start on top of general table descriptions in the users manual

Any comments appreciated!

[MichaS14a]

Thank you very much!
I will read it and give a feedback.

[TM_S13]

sounds pretty good.
will have a more deep reading as soon as I can.
thanks

[Legionnaire]

This is an update from my original 'diagnostic' document

http://www.nistune.com/docs/NIStune_Mapping_Guide.pdf

I've gone over HCR32 for a quite a number of hours tonight with the hardware maptracer and documented the tables which need a bit more explanation. HCR32 has more tables added and these will be available shortly. Next ECU targeted is the BNR32 and boost tables to go under the scope

I'll gradually add more ECU specific tables as I go but this is definately a good start on top of general table descriptions in the users manual

Any comments appreciated!

Good manual. I adore reading manuals. I think every Nistune user should have one on tap (when it reaches its release state). It is always nice to have documentation. This is where maturity of the developer can be clearly seen. This is the sign of a real business and of a good (in fact, incredibly great) product. Something extremely rarely seen among enthusiast-developed products i might add. Keep it up, Matt.

I now had only a brief reading and have a couple of comments and questions:

1)At the very beginning - if one block represents 5ms then injector pulse width in the first case seems to be closer to 6-7ms than 5.3ms. Second seems to be in order.

2)

The grey cells are the consult reported TP values. We highlight grey cells to indicate accessed cells and a darker
grey cell (not pictured above) to indicate closest accessed cell

To make it clear - if i dont use emulator - what TP value do I get in Nistune? Is it a TP that is recieved directly from ECU through consult (calculated by ECU itself) or is it a TP based on some formula using MAF voltage/VQ map value, calculated by Nistune on a laptop?

In this example ... the TP = 27. This sits between 24 - 28 on the load scaling.

Highlighted value is in the "24" column although 27 is definitely closer to 28 than to 24. Is this a feature of a tracing algorithm or is it ECU derived? AFAIK the real output is averaged somehow between two (actually four, but horizontally two) values from map, does it use weights for real calculation? e.g.

[(27/24)*{map value at column 24} + (27/28)*{map value at column 28}]/2

or more likely

[1-(28-27)/(28-24)]*{map value at column 28} + [1-(27-24)/(28-24)]*{map value at column 24}.

Italicized are weighting coefficients. Just interested in the mathematical formula.

3)

The basic works of the fuelling side of the ECU are:
Theoretical Pulse width (TP) = MAF Lookup * Injector multiplier + Injector Latency + Various enrichment
Injection Pulse width = Fuel table [ RPM , TP/256 ] * TP

In my humble opinion, "understanding TPW's" is a better place for this stuff than "PW limiting". Also AFAIK /256 (binary) means shifting 8 bits right. This actually means that MSB is the upper byte of the whole TP value, isn't it?
I also read somewhere that TP is somehow RPM dependent, is this true or 100% false?

4)

Larger injectors need a smaller pulse width to maintain the same amount of fuel at idle, but need a longer pulse
width at full throttle than the ECU would typically provide with stock injectors.

Hmm... that is really strange and counter intuitive to be honest. I don't get it. I admit that some people have experienced sudden lean condition at high load near rev limit, but it is unlikely to be traced back to larger injectors. The statement is true if airflow through engine has been increased significantly and map load scale has not been expanded accordingly, or load lattice has been expanded without map value recalculation, or VBOT aka latency has been set incorrectly, but it is not true if injectros is the ONLY thing that has been changed. This is a conditional statement and IMHO it should include conditions in which such an unusual state of affairs occurs.

5)

Theoretical Pulse width (TP) = MAF Lookup * Injector multiplier + Injector Latency + Various enrichment.

Is the 750 (example from the manual) value added to current theoretical TP as a numeric value right away, is it converted to some other value later (are msecs converted to some constant) or is 750ms interval added to output (total) injector pulsewidth? What dimensionality does latency have in the above formula? It is quite logical that latency is taken into account in final, real world pulsewidth calculation, but is it added to the theoretical pulsewidth? IMO latency is a final correction factor, that converts theoretical (ideal) PWs to real world, injector PWs, so I dont see why it should be added to theoretical PWs. I always thought of injector latency as a "time offset" so to speak. If injector X has less latency than injector Y, but their flowrate is the same, then it takes Y longer to open, but it also takes more time to close, so ECU just has to issue an opening command a {Y latency - X latency} msecs earlier, but pulsewidth is the same. On the other hand TTP is the index for accessing some specific point in the fuel map, in the above formula it represents engine load and i dont think that load has [msec] dimension at this stage. It becomes msec later, after total TP multiplication.

6)

The following graph shows the relationship
Blue = MAF (volts)
Green = TP (ECU raw value)
Purple = Injector Pulsewidth (ms)
As the amount of airflow increases, so does TP increase and resulting in a larger injector pulse width.

The relationship is clearly seen throughout the most part of the graph.. except the rightmost part, where MAF voltage keeps rising, but TP remains constant and injector PW jumps back and forth. I guess some lean condition is happening

That's it for now, I keep reading.

Cheers, Petros

[Matt]

I view manuals as a necessity. Without the further investigation into functionality of the ECU and a clearer explanation how to adjust tables, the user can get confused and spent a long time trying to figure things out

This results in us having to chase down problems and takes more time in asssistance on both email and forums.

Some of the gotyas are now involved with timing using various maps depending on temperature, throttle and gear positions. Its quite involved in some cases so I have to go through ECUs on a case by case basis here. Most should be similar in functionality to each other

1. First capture will need to be redone so it matches a bit closer

2. TP value you get in nistune is the same as the hardware traced ones. With hardware tracing it will flicker around 4 cells but only ever display one cell (hardware access) at a time

With software tracing you will get all 4 cells with the closest accessed one being darker grey. I can grab another capture of this to demonstrate with hardware tracing disabled

TP is passed directly via consult from the ECU itself. We do not calculate TP it would never be accurate enough and varies between ECU

Some times TP flickers around on load so getting the capture can be in accurate. I'll try and get it right in another screen shot

3. Correct with MSB is uppper byte of TP value. TP is used as an input into fuel/timing maps and the value of the maps can also then affect TP.

RPM can have an influence on TP. Those calcualtions are very basic at most

4. Sudden lean conditions may be due to TTP max limits being reached. Ensure that your injectors are running about 90% duty cycle and limits are increased and it should not lean out for the amount of airflow

5. It appears on bench testing that the latency value is added directly to the Injection Pulse Width. Adjusting 750us = 0.75ms will increase the injection pulsewidth regardless of load/RPM by that amount

Yes latency should be moved out of this formula and into the pulsewidth forumla

6. We probably hit a limiter or injection max condition in that graph

[PL]

Hi Petros,

I just had a quick look at this and where Matt talks about larger injectors needing larger PW at high load I think he's meaning that usually guys who have fitted larger injectors have also increased boost etc. So you'll tend to find that in a turbo engine tuned for greater HP TTPmin will be less due to the bigger injectors but TTPmax will be larger due to the greater airflow from higher boost.

Could be clearer. I'll beat Matt later...

PL

[Herb-86T]

relating to the timing map that can cause issues at 48-65 degrees... is this in the z31 binfile? timing goes retarted around this temp. for me...

[Matt]

thats on the list. doing a search on these forums reveals the problem identified a long time ago with the retardation during warmup on the low end of the map

Z32 next (started working this last weekend until i fell ill) and then VLT/R31/Z31 afterwards

[J30_VG33ET]

I had some time to go through the document and appended some notes. Hope they help. Let me know if you can't read them, I did the edits in Preview, but can see them in Acrobat at work.

Overall a fantastic resource, and clearly setting this product above the market.

[Matt]

just started reading through it. excellent points with your comments. i've saved a copy and will start going through it

i've been working on more documentation updates over the last weeks as well as software updates. gets stalled at times but still happening

[Matt]

comments have been worked on in the document and draft C is now available on the website

added maps for HCR32 etc are also in the latest release which is available now