Thread: Interesting SAFC correction information.

Yes this is an interesting find that should work well with some good tuning skills. In actuallity the safc can correct more than -50%, it wouldnt work the other way around being the stock ecu hotwire is 6 on our cars. If you run out of room on the correction part you can always bring down the out on the hotwire setting. Dropping the out on the hotwire setting will reduce the input to the ecu reducing fuel %.

For example my settings for my in and out are at 2in 6out for my z32 maf. The stock maf is 6 so the safc changes the input from the z32 and adds volatage to it to match what the stock maf would see. If i change my out setting from 6 to 5 the safc wont add as much voltage to the input to the ecu resulting in less fuel.

All you would really have to do is figure out how much of a percentage the change from each hotwire setting is and you can use that to your advantage to take out more fuel, meaning more than 50% more on the 200% range of adjustability. Thus allowing you to use 850cc injectors with a stock maf. I will have to do some calculating to figure out the voltage percentage change on my safc to get some sort of percentage change for each setting

The quoted text might work in some cases but is wrong.
IN & OUT have nothing to do with injectors.
IN "says" to the SAFC what output to expect from the MAF
OUT "says" to the SAFC what it should send to the ECU as MAF signal.

They only translate the MAF-input to MAF-output to help you change MAFs. And because it does some transformation of the signals, IF In and Out are different, there is this nice "tidbit": If you use ANY ECU with its original MAF, you can have any pair of same values there and it will work fine.

i.e. Stock B13 SR20DE ECU with its stock B13 SR20DE MAF will work fine with In=1/Out=1, In=2/Out=2, ..., In=6/Out=6.

Obviously, if you know the difference between MAFs you can "hack" an In/Out than the ocombination that can also PARTIALLY (and definitely not in the entire MAF-load range) account for injector changes ..

from the above WRONG quote you can infer the following...

OEM inj + OEM MAF = 2/2
OEM inj + Z32 MAF = 2/5
^
|
In general this should be Wrong. The OUT value says what the ECU expects, so this should not have changed, the In value (that says what goes from the MAF and IN the SAFC) should have. However, IF the MAFs were relative to each other at the same ratio that the 2 and 5 MAFs are then this would be OK.

Sard850 + Z32 MAF = 2/2

Now ii step 3, for the quoted "guidelines" to be actually working, th efollwing happen:

The In/Out = 2/2 means that the SAFC will not change anyhting in the signals.
Since the Z32 MAF is bigger than the original, at the same load It will output a SMALLER signal than the original to the SAFC which will pass it unchanged (due to 2/2 to the ECU).

The, ECU for a given load (TP, MAF output), rpm, etc., etc., calculates an injector pulse. In this case, since it thinks that the MAF signal indicates a smaller load, it outputs the pulse that would be correct for the original injectors. Sard850 get the injector pulse and the actually output 850/370 = ~ 2.3 times the fuel that the 370s would.

Moral of the story.. for the quoted assertion to work, the original MAF should be reading close to Z32/2.3 readings... something like the same relationship that Z32/SR20DE MAFs have.

i know the safc in and out are relating to the maf only. but im just saying you could use this to further reduce fuel to run bigger injectors. all you would have to do is figure out the % change from each out setting.

what would the corrections be like for 850cc/Z32 MAF on a Bluebird ECU?

Would it be the same 2/2?

no because the bluebird ecu is set for 370cc injectors it would probably be more around 2 in 3 out but dont quote me being i havent done the %'s yet but you would kinda have to test tune on your own to find the best setting for your setup

I've always thought they were supposed to be the same setting.

So what would cobra maf and MSD 50# be?

i dont know what hotwire rating the cobra maf is. In that case it would be whatever hotwire rating the cobra maf is as the in and the out would be 6 if your running the stock ecu. The safc can adjust to the 50lb injectors in its normal settings.

Guys this only works if you plan on going over the -50% the safc settings can go up to. The hotwire rating on the safc is meant for the maf only, not the injectors. You can just use it to your advantage if you know what you are doing tuning wise to run more than -50% to run bigger injectors than 550cc.