Quote:

---

I have a dry NOS kit for my 99 si. I just got it, and I am only using a 60 shot. 70 for track. I dont use it that much. I dont want to have to be worried about running lean, so i was wondering, if i use my V-AFC with the nitrous, will it trick my ECU to much, and cause problems? I only want to do a +1 or +2 correction when nitrous is being used. I know that I should get something better, like hondata, but i dont have that kind of money.

---

I would be weary of running the Vafc. A vafc by nature will tend to advance your timing, which is a bad thing...

Be careful as stated earlier...GET IT TUNED.

Quote:

---

VAfc advances timing only if you remove fuel (and only 0.5-1 deg for up to 10% fuel correction). If you add fuel, timing stays almost the same if not increased by just a little (depending on altitude)

---

The majority of the time you have bigger injectors and are removing fuel.

Such as the 450cc with the vafc hack.

I was reading up on H-T about Vafc's and timing, they do advance timing but unsure as of yet by how much.

Quote:

---

Quote:

---

VAfc advances timing only if you remove fuel (and only 0.5-1 deg for up to 10% fuel correction). If you add fuel, timing stays almost the same if not increased by just a little (depending on altitude)

---

hacking or running the FMu/afcs. I wouldnt advance too much. Shit I run near stock timing.
I've seen some bad shit with the timing increase.


The majority of the time you have bigger injectors and are removing fuel.

Such as the 450cc with the vafc hack.

I was reading up on H-T about Vafc's and timing, they do advance timing but unsure as of yet by how much.

---

Quote:

---

OK so this first post, old to the game, new to this forum.

Quoted by: EXVtec, "A vafc by nature will tend to advance your timing, which is a bad thing..

Now, as for the timing...THE S-AFC AND V-AFC DO NOT CONTROL TIMING!!!

---

You need to understand how a ecu reads a map signal and how the Vafc will alter that signal.

I didn't say the Vafc directly controls the timing.

The less load an engine has, the more the timing can be advanced. So, the part of the ignition maps with greater vaucuum have more advance in them. Reducing the fuel in the VAFC makes the computer think there is more vacuum, so it looks up values farther to the left in the fuel and timing tables. It is there that it gets the smaller injector values, but also the more advanced timing values.
Moral: Removing fuel with a VAFC causes the timing to advance.

Does that clear things up?

Quote:

---

^ And we have a winner. Nitrous and any form of piggy back can be a deadly combo, especially if you are unsure of how they work. Stick with a ECU chip (non ebay) professionaly tuned and you will be in a lot better shape.

---

Quote:

---

im running a NOS 50 shot on my corolla and am planning to install an S-AFC soon - from what i understand from this discussion, timing will be advanced if fuel is removed - what if fuel is added? This is what i expect to be doing with the safc as I want to prevent detonation.

so, by following this line of logic -wil adding fuel actually retard the timing at all? I know retarding ignition timing is unnecessary with such a small shot of nitrous, but is this a legitimate line of thought?

---

It will be fine, assuming everything else is in check.

Quote:

---

good to know. thanks. btw what part of WV are you in? I was born in Beckley and come up usually once a year for a football game (came to the Virginia Tech game this yr - their only loss lol long trip home)

---

P burg...

Not far..

Quote:

---

Jeez guys a used S100 isn't that expensive...

---