AlwaysinBoost

iTrader: (17)

Ok, I'm trying to tune my car using an my AFC and pocket logger. I was wondering what o2 sensor readings in volts = what A/F ratios? I'm seeing O2 sensor numbers from .88v - 1.01v depending on TPS & timing.

Also why is it if I'm at part throttle I get huge amounts of timing advance like +38 but as soon as I go WOT the timing falls down to 4 or 5?

Warrtalon

iTrader: (6)

I gave you the estimated conversions previously in our long PM exchange.

You're only concerned with timing at WOT, because that's when you're in open loop.

You also are only concerned with the o2's at WOT. If you see .88 at WOT, you better add some fuel.

bolsen

iTrader: (2)

Is it just me, or is tuning with a narrowband seem like a baaad idea?

Warrtalon

iTrader: (6)

It's just you.

Wideband is obviously preferable, but we don't all have that luxury...

AlwaysinBoost

iTrader: (17)

I just checked my PMs and you must have me confused with someone else cause we never discussed O2 values before... otherwise I wouldn't be asking the question now. But if you know the answer by all means enlighten me.

Luckly I don't see anything lower then .94 at WOT yet. So far I've been able to take my peak timing which was around 15-16 @ 7k and bring it up to 20-21 @7k. What is the ideal voltage to tune for?

Now I'm trying to work on my mid range from 4-6k and see if that doesn't increase the total timing up top.

Warrtalon

iTrader: (6)

Ok, perhaps it was someone else. I have more PMs about this stuff than I can shake a stick at...

I'll talk to you about it in the S-AFC forum, because this will get detailed.

propellerhead

iTrader: (3)

Actually I don't think it's you. Not offend anyone but I think tuning with a narrowband is a bad idea. I mean, if the AFR range you want to tune within is between ~14.25 and ~15.25, then a narrowband is okay. I'd be interested to see the long term results of a full boost WOT tune performed using a narrowband sensor.

li1p1aya

iTrader: (1)

I would think, correct me if I am wrong, but the wideband O2 sensor would complement the pocketlogger and vice versa. Though you can tune with just the wideband you would get a better understanding of what is going on in your car with the pocketlogger.

EVOONYOASS

iTrader: (2)

I would strongly recommend NOT using the stock O2 sensor to tune your vehicle. I used a OBDII pocket logger on many different occasions to tune my SAFC and each time I threw it on the dyno, the a/f was way off from what the logger read road tuning. I used two seperate loggers just to see if one could be wrong, but they both read very close. The stock 02 is just not accurate enough. I tuned in the fuel trims for high/low and it just didn't come out anywhere near the same as what the wideband read on the dyno.

I consider myself pretty good with a SAFC and have tuned many cars with them, but without the proper wideband O2 sensor its all guess work. Use a friends wideband or throw it on the dyno and just do it right the first time.

propellerhead

iTrader: (3)

I think a pocketlogger can be somewhat useful but really the sampling rates through an ODB2 port are **** poor slow. Slow enough to the point that you can't always see rapid changes in timing or dumping fuel by ECU reacting to knock.


AlwaysinBoost, bear in mind that the voltage output from a narrowband sensor will always be bouncing up and down while the ECU is in closed loop mode. This is because the ECU is always on the hunt for stoichiometric combustion, bouncing back and forth in a really norrow range between rich and lean. While this works great for maintaining an AFR of 14.7, the narrowband doesn't have the range necessary to tune within the areas you're trying to tune. Take a look at this graph of the voltage output from a NBO2 sensor.

Warrtalon

iTrader: (6)

The results are in my sig, but I don't know if that counts as long-term.

Of course, I'd prefer wideband, and I suggest that to anyone who asks for my help, but my o2 readings have been accurate from day one, and that's after going on the dyno twice to verify. I also watch the timing as a safeguard against potential faulty o2 readings.

AlwaysinBoost

iTrader: (17)

I know the narrow band o2 isn't 100% accurate that why like warrtalon said you watch your timing as a second way of seeing knock. My question is really what voltage should I be shooting for? Some old posts I read that were mostly geared towards 1g DSM's said like .88v but I "think" thats too lean

I've gotten my O2 to read all .96v from like 5k up to 7200+ and also .94v from 5k to 7200+ but my total timing up top has never been above 21* at like 7100rpm. Should I be tuning for .92 or .90 or is that too low? what does .96v, .94v, .92v, and .90v translate into A/F ratios on the narrow band O2?

BTW I do have an LM1 on my other car and as soon as I get an exhaust for the EVO I will be switching it over.

Another thing I'm having trouble with is getting my timing to not drop like a rock in the middle of the RPM band as soon as I go WOT. At 3.5k I will have 21* at part throttle but then as soon as I go WOT it will drop to 3 or 4 (sometimes as low as 0*) and then start to climb up from there. I tried adding a little fuel cause I thought maybe I was getting a little knock, it did change the 02 values from about .90 - .92 to .96 but the timing stayed the same... any ideas?

Warrtalon

iTrader: (6)

This just means you haven't been reading all those threads in the S-AFC forum. All of this information is in there:

1) Tune for .92-.94 from 3500-7500, preferably .92s across the board. Add fuel and go for .94 if you see knock anywhere.
2) Shoot for a peak timing of 20-21 above 7000
3) The factory ECU maps ALWAYS cause timing to bottom out when you hit peak torque. This is unavoidable when using an S-AFC unless you have a flash and is partly why flashes are superior in function. With a Dynoflash, Al keeps the timing at 7-8 through the peak torque area, then lets it climb beyond 5k. This is why flashed cars generally have a lot higher torque spike at 3800 and then have a broader torque curve the rest of the way. Additionally, this additional mid-range timing gives more mid-range power. We just have to deal with this deficiency when using the s-afc.

matt55

iTrader: (12)

on 93 ?
If so what about on 105-110 octane
also iam goin to go to the Sacf forums and do some reading

thanks

EDIT

I searched and found...

".92 is where you want to be on pump gas, while .88/.89 is too lean, unless that's on 100oct," ---Warrtalon

propellerhead

iTrader: (3)

You mention your NBO2 readings are accurate. Have you correlated your voltage values with a WBO2 for reference? How much does EGT/sensor temperature affect the accuracy of your readings? To what AFR does a voltage reading of .94V indicate? Conversely, what would the voltage value be for an AFR of 11.5:1? If I had a narrowband installed in my car I'd log the voltage output and compare it to my wideband readings and find out for myself, but I don't.

Just to clarify, I'm not trying to knock your tuning methodology. It's just that based on the voltage output curves I've seen for a narrowband O2 sensor I don't see the dynamic range necessary to do a safe tune.