Tuning without Dyno
Racer
Joined: Mar 2008
Posts: 457
Likes: 52
From: Elkhart, Texas
"To go a step further you must also use a "wideband 02 sensor"
as the stock narrowband 02's are not very accurate "
This is EXACTLY what I said---So I cannot see where you can infer that I said the narrowbands are accurate with boost or highly modded engines--- The only time I use narrowband readings is in a totally STOCK engine with only bolt ons not including either shorty or LT headers
Data logging with EFILIVE will give you tremendous 02 readings Most importantly The "average 02 readings" Which you want to be between .400 and .550 millivolts to get you a Stoich of 14.68-1 at P/T
and then at WOT only in the gear ratio that s closets to 1:1 you would want the voltages to have a max of about .875 to .900 to get a WOT reading of about 12.5:1 a safe street AFR
The modern day narrowbands are far superior than in the past AND on a bolt engine with NO headers YES their readings are very close and safe for a street hod rod--
as the stock narrowband 02's are not very accurate "
This is EXACTLY what I said---So I cannot see where you can infer that I said the narrowbands are accurate with boost or highly modded engines--- The only time I use narrowband readings is in a totally STOCK engine with only bolt ons not including either shorty or LT headers
Data logging with EFILIVE will give you tremendous 02 readings Most importantly The "average 02 readings" Which you want to be between .400 and .550 millivolts to get you a Stoich of 14.68-1 at P/T
and then at WOT only in the gear ratio that s closets to 1:1 you would want the voltages to have a max of about .875 to .900 to get a WOT reading of about 12.5:1 a safe street AFR
The modern day narrowbands are far superior than in the past AND on a bolt engine with NO headers YES their readings are very close and safe for a street hod rod--
Here is a chart from the internet showing the difference.
The accuracy and the ONLY accuracy of a narrowband is the switch point, as designed. See how it flattens out on both curves? That will tell you a very broad range of Air/fuel ratio, but is not something to tune by.
Drifting
Joined: Nov 2017
Posts: 1,392
Likes: 303
In theory, sure. But again, until someone actually plots the response curves of the stock sensors and a wideband, it's just theory.
If nobody else can make that plot I'll do it myself. Could be a while though, I need to write the software to do it first.
If nobody else can make that plot I'll do it myself. Could be a while though, I need to write the software to do it first.
Burning Brakes
Joined: Sep 2016
Posts: 979
Likes: 102
Winner. Thats the biggest challenge I face tuning cars on the side, is tuning wide open. I dont want to get a ticket for tuning someones car WOT on the freeway(thats why I only tune on the dyno for WOT now). Like Reid said, WOT should be tuned in 4th gear and thats 155-160 @6.8k. Im not doing that on the freeway lol
The biggest problem is that you will never have consistent enough results on the open road anyway. Spark test is the best thing, even with a dyno. Spark test over Hp tuners scanner on the street for sure.
Racer
Joined: Mar 2008
Posts: 457
Likes: 52
From: Elkhart, Texas
There is a relationship but nothing I would be confident to publish as the difference between "rich" and lean is in the 100mv range most of the time at best. Very low resolution in the grand scheme and having a wideband for the average tuner is going to be the way to go; especially when you have the ability to adjust the switching point in most OEM based flashing software. Plus a wideband is CHEAP now.
See the below. This is just a sample of a log of my car (500+MB of data alone on this car, 384 logs and hundred of tune revisions). I had just turned back on the MAF and was trying different AFR points on the dyno with various spark timing combinations to see what the motor liked.
FYI back in 2007 this was shared but is only valid at a specific atmospheric condition.
14.7/1- 0.50
14.6/1- 0.60
14.5/1- 0.70
14.2/1- 0.80
13.5/1- 0.85
13.2/1- 0.90
13.0/1- 0.92
12.5/1- 0.94
12.0/1- 0.95
So 800MV is around stoic for a E10 gasoline blend, assuming the PCM is calibrated correctly. 900MV is a full point richer. That was a chart on this forum in 2007. Then to go another AFR point it only takes 300MV (13.0-12.0 is .920 to .950)
Much like the graph I posted the further you get away from the switch point the "flatter" the reading gets.
Drifting
Joined: Nov 2017
Posts: 1,392
Likes: 303
Cool, it's nice to have actual data. You can really see how the accuracy degrades as you move away from stoich. It's a classic narrowband after all.
I plotted an aftermarket PLX wideband sensor against the factory sensor in my 05 Subaru over a decade ago, and the relationship is almost linear all the way down to 11.2. (You do have to move the factor sensor to a location downstream of the turbo, but that's easy enough.) Even after all these years, plenty of people still insist the factory sensor in that car is a narrowband. So you can see why I hesitate to believe anyone who doesn't have data.
I plotted an aftermarket PLX wideband sensor against the factory sensor in my 05 Subaru over a decade ago, and the relationship is almost linear all the way down to 11.2. (You do have to move the factor sensor to a location downstream of the turbo, but that's easy enough.) Even after all these years, plenty of people still insist the factory sensor in that car is a narrowband. So you can see why I hesitate to believe anyone who doesn't have data.
Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
Narrowband (binary, switching) O2 sensors also vary voltage with temperature as you go off stoich. There is neither control nor compensation for this when trying to read them in the rich region. Two data points both taken at "900mV" could represent wildly different AFRs depending upon both sensor temp and backpressure. Welcome to 1997 if you want to try and tune your L98/LT1 that way with your Scanmaster and MAFterburner piggyback. 
If you plan to calibrate properly, you NEED proper tools. Decent quality widebands are available under $400 now, even if you're not gonna get the pro tools like some of us use.
If you plan to calibrate properly, you NEED proper tools. Decent quality widebands are available under $400 now, even if you're not gonna get the pro tools like some of us use.
