Z31 trying to learn to tune

[samwashere139]

wondering if anybody would be willing to take a look at my tune and offer any advice...
z31
hx35
old benz 490cc injectors (have have seen people say theses are anywhere from 420-490cc) the pn on my injectors when looked up on witchhunter show 490 at 3 bar
fuel pressure set to 43.5psi
intercooled with lots of piping
stock maf
nistune withOUT feature pack
when using "resize injector" feature from stock 180 to benz 490 it show k value of 222. at that time the car seemed to drive best under low load at 222-220 k value so im guessing that the k value is somewhat close.

when I first used resize injectors I selected the auto adjust load scales box and it seemed to mess up a lot of the tables and load scales. I went back and started fresh with just changing k value to 220 then found my max load (around 70 TP(index)) and set my max load for fuel and ign to 75 and interpolated back from that.

few questions?
1. when initially tuning k value should i be using a base map and load scale to cruise in while trying to obtain around 14.7afr?
2. when adjusting load scales for fuel and ign how can I be sure that the load scale aligns properly with the columns on the map?
I think this is how I devolved blow by with the last engine.. i think my load scales were off causing the curser to access columns in the ign map that were too far left or too far right (so way too much timing or way too little)
3. can I assume that if I replicate the load scale graph from a base table to my load range that the timing map will be somewhat properly aligned with the load scale?

[Matt]

Two things change K
(a) Injectors - reduce the amount of injection time by lowering K (but adversely affects load referencing) so K started 607 initially, and now dropped by less than half
(b) MAF - you haven't changed apprenty but it has been rescaled (not recognised) so not sure what is going on there

Auto adjust scales does basic math. So if injectors are 2.5x then it will reduce scales by this much. It is only a starting point to keep load referencing the same

If you find your max load is 70-75 TP then just leave that, unless you move K again

Base mixtures just adjust using K constant at cruise (14.7:1 AFR with near 0% trims)

Latency 450uS seems a bit low. Would expect around 750us stock still

[Matt]

Compared your file against 26P00 btw and bit2 was ticked in feedback switch 1

Not sure on the parameter, but may have undesired consequences (undocumented)

[samwashere139]

Thanks for the reply Matt! I believe my board is a 21P01 (1987) I remember having issues when first trying to consult using the ecu number. I thought I remember reading somewhere that some of the address file locations were different between 21P01 and 26P00?

im not sure how the MAF Translation table and MAF Translation grid got messed up.. i must have done something wrong when I first did the initial injector resized bc some of the tables were maxed out at 255 all the way down. Might be better for me to start from scratch and just change what i know needs to be adjusted.

also not sure how that bit2 box got checked.

found some of my issues were boost leaks. I'm pretty sure i adjusted k value after finding my max tp(index) around 75 so i will need to rescale accordingly. ended up going way lean and I'm sure way too advanced timing on the track and have blow by now, but once i get the next motor ready i plan to watch boost(psi) compared to tp(index) and make sure timing is safe at that point in the load scale and map. thinking about having timing the same in large blocks as soon as it gets on boost so i can keep it safe until I can get a pro tune.

thanks again for the explanations