a/f ratio input for all use newbies

Simple question this time. I just installed my new S-AFC 2. I dont have an a/f gauge yet so i just leave the correction factor at 0% and dont f with it much for now. Question is how do you know with/without the a/f guage if your mixture is good or not. All I now is if its to lean it will start to smell of hot mettal, probaby already doing damage, or if to rich it may back fire and smell of gas.

list of info a newbie like me may want to know, me personaly im not f'ing with it till my experianced friend helps me. :uhoh: :nono:

-how do you know if your near detination?
-how do you know if your doing damage to your car, befor the abvouse boom? (this is the big one)
-how do you tell if your mixture is actualy doing better and you dont just think your faster? (The human mined is a crazy thing)
-maybe even post some good a/f settups for normal driving, and racing.
-not all of us have turbos like me so if you have the know how please share it with those with both setups.

Simply just post a/f related topics here.

:eek7: man i gotta quit writing these books :eek7:

Oh, yea and what kind of a/f gauge is good to use?

This applies to NA and turbo setups.

-how do you know if your near detination?

You'll hear a metallic rapping sound from within your engine when its at full, or near full, throttle. Power loss will accompany this sound. Check your spark plugs, if you see a blistered, amber glaze on the insulator you are burning too hot; maybe even getting detonation.

-how do you know if your doing damage to your car, befor the abvouse boom? (this is the big one)

If you experience either of the afformentioned symptoms, you've done some damage even it is only minute. Mild detonation should burn your plugs first and then the head gasket. Change it AS SOON as it blows and you can save the surface of the block and head.

-how do you tell if your mixture is actualy doing better and you dont just think your faster? (The human mined is a crazy thing)

Experiment: Stop watch, E.T.s, trap speeds, ease of burnouts, dyno tuning, and if you have the talent (the magic touch if you will) sound and feel (your butt in the seat) can all give you tuning clues. You could race against a friend's vehicle as a base line. Tune yours and keep theirs the same then race again. Go to a racing event and most of the people with tell you to listen, smell, feel, and track times are the way to go.

-maybe even post some good a/f settups for normal driving, and racing.

This is for my 1991 240SX LE/S w/no cat, no engine fan, no muffler, extra advance, and S-AFC.
1. advance your ignition timing until you experience mild detonation.
2. set your AFCs low throttle to to 25%
3. high throttle to 75%
4. Ne points is up to you, mine is 2500, 3000, 3500, 4000, 4500, 5000, 5500, 7000
5. I set each Ne point to about +5% for high throttle, 0% on low throttle if you have stock injectors
6. run in 3rd gear from idle to revlimiter, listen from detonation and feel for dips in your torque curve.
7. add fuel at the points where you experience detonation until it is gone, then add another 2-5% just for a safe margin
8. add and subtract fuel at any dips in the torque curve to smooth them out, again more being safer

My S-AFC set up sheet is as follows:
sensor type: 1
sensor #: in 5, out 5
Dec. air: Thr 8%, Ne 1 +10%
Ne point: 2500, 3000, 3500, 4000, 4500, 5000, 5500, 7000
Hi Th: +9%, +13%, +15%, +18%, +22%, +25%, +22%, +13%

Peolple will disagree with me on these settings, what information you take in is up to you. These settings work best for me, you may and more than likely will need something a little or even a lot different.

-not all of us have turbos like me so if you have the know how please share it with those with both setups.

Turbos aren't much diferen't just take 0.5 degrees OFF your advance for each psi of boost. A timing pack will help you here. Your tuning is more critical as your engine becomes more powerful and more high strung.

-Oh, yea and what kind of a/f gauge is good to use?

The ones that plug into the stock O2 sensor are only a warning gauge, they can't tell you how rich or lean you are. Stochiometric (14.6:1) is too lean for optimum hp; its simply the optimum for the catalytic converter to work. The car gose richer than this at full throttle anyway. Greddy makes a decent system that has its own wide band O2 sensor and actually gives a numeric reading of the A/F ratio. I've used this one on past cars and it works quite well but there is a warning in the manual that it isn't very accurate and serious engine damage could result from tuning off its readings. So it is more or less just a warning too. It costs about $350. The black box systems like many race teams use in tuning are made as tuning tools but they cost over $1000. As I said, I used the Greddy system to great effect so the warning in the manual is probably just to satisfy their legal department. I don't have a A/F gauge on my present car and would rather tune by my own God given 'sensors'! Too few people have the talents our ancestors held and I hope that you join me in developing such talents in ourselves.

i agree if u know your engine you can just tell if its running lean or rich. You can feel power drops and you can hear detonations and most problems

more replies like DWF's are exactly what im looking for. Thank you

check ka24de.com for a good wideband o2 sensor.

also, many people read their spark plugs to see if their engins is running rich or lean.

I Don't know why I didn't think of this before... The best thing to do is to put all the OEM stuff back on and test the e.g.t.s with a pyrometer. Then put your mods back on and tune it so the modified e.g.t.s match the stock ones. This may not make the most power but its pro'ly the safest way to do it. Pyrometers sell for about $110 and any decent shop sells them. You can also get them from Jegs, Summit, etc...