Injector Size change results in car stalling

[judasentinel]

Hi everyone.

Finally installed NISTune and I must say the initial impressions are very good.

Now for the weird part. This is my setup and maybe some of you may be running similar setups or at least can help me:

R32 Skyline with RB20DET ECU, harness/loom running an RB25DET engine. I am also running a Garrett GT3071 sized turbo. Before installing NISTune, I was running a tuned chip made by a fellow Skyline owner in Canada. The car was running good, although the chip was designed for stock turbo.

Now when I bought NISTune, I loaded up the map under the folder for R32, which is R32 ECU running R33 maps - I assume it is the stock RB25DET map , but I discovered in the injector size setup screen on Nistune that it says 270 (is that 270 cc??). However, RB25DET injectors are 370cc. So I changed the injector size to 370cc. However, as soon as I do that and then start the car with the new injector size, it stalls. And my wideband starts to tell me that I am running super lean in ALL rpm and load ranges, with the new injector size. The map stays the same but the load values change, but with no effect on preventing stall. Shouldn't that be reverse? And I cannot lower the fuel map cell values beyond a certain number, so it doesn't allow me to change them enough to get even stoichiometric reading, let alone run a bit rich.

Does anyone know if I am changing the injector size correctly or if I need to change it at all? Does anyone have an R33 base map?

Secondly, I am noticing that the values displayed in each cell being used while the car is running, are around 2-3 points lower than what my wideband gauge shows. Is that normal? Should it be so or do I need to look into something to make them the same? If I change the fuel map value to stoich (14.7), the wideband goes to around 17-18, and that is dangerously lean.

Any ideas?

I would also like to understand what latency and pulse-width values need to be for my tune.

If Matt sees this, can you help me out here, mate?

Thanks,

Munib

[modulation]

but I discovered in the injector size setup screen on Nistune that it says 270 (is that 270 cc??). However, RB25DET injectors are 370cc. So I changed the injector size to 370cc. However, as soon as I do that and then start the car with the new injector size, it stalls.

I believe you'll need to disable o2 sensor feedback and fine-tune your K constant. Changing your injectors via menu options is the first step, but the K value is a rough guess and it looks like in your case it's not close enough. View Chapter "10. Resize Injectors" in the Nistune users guide for more info.

Secondly, I am noticing that the values displayed in each cell being used while the car is running, are around 2-3 points lower than what my wideband gauge shows. Is that normal?

Yes, the value for the target A/F ratio seems to be a rough guess/approximation. The table/map stores the Injector Pulsewidths not AFR. I have a LC-1 wbo2 and I always runs 1-2 higher then the targeted AFR that it shows on the tables.

I don't really ever bother looking at the predicted AFR. I use the AFR 3d Trace and then increment/decrement cells on the Fuel Map to get closer to what I want. Then I run that map and log more data. Get home look at the new AFR 3d trace and then edit the map again. Rinse/Repeat..

[judasentinel]

The Nistune tuning guide ...........is that the one by Pete? I have a copy of it, but its mostly blank in the end. Does anyone have an updated copy of it?

Where is the AFR 3D trace? I couldnt find it in Nistune.

How do I change the rpm level scale values? It goes only up to 6400 rpm and there is nothing after it. My engine goes to redline at around 8000 rpm. How do I change 6400 to 8000 and all other values as well?

I am very surprised at you saying that the fuel map shows pulse-width values and not AFR values. Isn't 13.4 the air-fuel ratio in a particular cell? Or if it is pulse width, is it in ms? Im confused. What does the ignition timing timing map show? Degrees of advance or is it also some kind of a derived number?

[modulation]

I was speaking of this one:
http://nistune.com/docs/NIStune_Softwar ... Manual.pdf

The data stored in the fuel map is simply the injector pulse width.
You can use some math and estimated numbers and arrive with a few different things such as duty cycle %, AFR, etc. (as show by the drop down box) but the actual value stored is how long the injectors are open for.
I'm just saying don't pay attention to/worry about the AFRs on the fuel map.

Timing tables as far as I know (and I don't know that much) ALWAYS store how many degrees before TDC to spark (or initiate the spark process as I'm not sure if the dwell time is calculated into the equation.

To get to 3d AFR map goto menu options:
Operations -> Wideband Input Tracer

[judasentinel]

Gotcha!!

Now how do I change the scale for rpm on the maps? It only goes to 6400 rpm and I need it to go to around 8000 rpm. I am guessing its done in the map scale section, and it changes the scale, but do I then need to change the values too or can I continue with the values in the fuel and ign maps?

[Matt]

I've sent an email through but basically in summary, I've put all the R33 tune into your board.

Maps have been copied and adjusted K constant (injection multiplier) for your vehicle, so it should hopefully run straight off if I got everything right

Use the HCR32 address file for tuning with, or ECR33 address file for looking at the RB25 ROM files (now available in latest ROM pack under 'Type 6')

Injector size displayed in the 'Resize injector' window comes from the address file which you load. There is a parameter INJECTORCC which holds the stock injector size for each vehicle

This will not change when you resize, because it only modifies the K constant and (if ticked) some of the maps

You can move the cursor to the RPM scale on the fuel map and use +/- to adjust or directly go to the scales themselves and modify from there

Then you need to change the AFRs to match your new scales. Try and smooth the existing tune into your old scale range (upto where you set your new 6400 row) firstly and then set your new AFRs in the upper scale rows afterwards