Nistune Forums

This will be my first post on this forum so, Hello!
I recently decided it was time to learn how to tune, since it is something that would open a lot of capabilities for my drag car.
I've decided I would start on my drift car which is an 89 s13 with a Ka24DE swap. Manual Trans. B44 G07 ecu

I just installed a Turbo setup which consists of:
Gt2871
Yellow STI injectors (550cc from my understanding? roughly 1020uS?)
ISR z32 MAF (Draw through)
No BOV
Nistune with Feature pack

From my understanding, being that I have the feature pack, I do not need to adjust my K constant when resizing my injectors.
I have searched and found a ton of posts regarding this, but none have fit my issue
I have a Z32 MAF on top of the injectors, so if I leave my K constant the same (only resize based on TIM) I am not allowed to change my MAF within the program. To get around that, I've resized the injectors based on both K constant and TIM, which then allows me to resize the MAF.


Now that I'm typing this I'm Guessing I should not be using the resize function at all for either the MAF or the injectors since I have the total injection multiplier, can someone confirm that this is the case? If this is the case do I need to check the boxes for Load scalers, Load max limit and cranking tables? or leave them unchecked?

With the tune I have, I have been able to get the car to run and drive, but I am struggling with getting a solid idle. I have adjusted the TIM to be around 14.7 at 2000 rpm. I would then try to mess with my injector latency along with my MAF translation table to reach roughly 14.0 at idle. (targeting 14.0 per the advice of the dealer/tuner I purchased my Board from) when I get both my idle along with part throttle around what my target AFR is, I then experience a stumble when revving the car off idle. Also, when I rev the car anything above 3k rpms, the engine will not catch idle it will dip extremely low, go super rich (9.0:1) and slowly climb back up to my target AFR.

If anyone has any insight on what I could potentially be doing wrong here, I would greatly appreciate some assistance!
I would also appreciate if someone had base tune for a similar setup that I could take a look at and see what all tables were changed.
Thank you in advance for any and all help!

Hey Caleb

It seems a bit confusing but if only adjusting injectors, then only TIM needs changing

However if adjusting MAF and injectors, then Nistune will direct you do adjust the MAF firstly (increasing K) and then injectors (dropping K back near factory levels)

With the S13 KA24DE the K constant is pretty high, and causes a problem with changing to Z32 MAF So we need to do the reverse. Adjust injectors firstly, and then MAF Load scalers tries to adjust the scalers based on difference of size. Since doing both MAF and injectors, keep it unticked for both injectors/MAF
Leave cranking tables and max limit ticked

After doing both, we end up with K constant around 37,330 which is not too far from where you started

So the load scales should not really need adjusting. It won't be until you go into boost and see how far your trace cursor goes if you need to adjust K further (so the trace cursor stays in the scales). Use TIM to adjust mixtures

For 550CC I would use about 700uS latency to start with

For the issues you are seeing, a log (with AFRs) would be helpful as well as current tune file

Matt wrote: ↑Mon Sep 26, 2022 3:42 pm After doing both, we end up with K constant around 37,330 which is not too far from where you started

So the load scales should not really need adjusting. It won't be until you go into boost and see how far your trace cursor goes if you need to adjust K further (so the trace cursor stays in the scales). Use TIM to adjust mixtures

For 550CC I would use about 700uS latency to start with

For the issues you are seeing, a log (with AFRs) would be helpful as well as current tune file

When I get off work and home(Tuesday for you!) I will start with a new stock map and copy what you told me here and then take a log of that. I was going to post a log with my original post but didn’t think it would be beneficial if I had things incorrect in the setup

Thank you Matt!

Matt wrote: ↑Mon Sep 26, 2022 3:42 pm After doing both, we end up with K constant around 37,330 which is not too far from where you started

So the load scales should not really need adjusting. It won't be until you go into boost and see how far your trace cursor goes if you need to adjust K further (so the trace cursor stays in the scales). Use TIM to adjust mixtures

For 550CC I would use about 700uS latency to start with

For the issues you are seeing, a log (with AFRs) would be helpful as well as current tune file

Here is my updated tune, I started from scratch with your suggestions, along with 2 logs. Both logs are very similar, the one titled "Cruising speed" should have a few sections of just idle where you will see my struggle. It looks to me like the rest of the changes have worked in my favor, I may need to add a little fuel through the TIM to get it a little richer at cruising speed.

Yeah that injection multiplier just needs a bit more richening up (see around 14-15.5 AFR) and that should start running better