how do you convert o2 voltage to a/f ratio?
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Honda-Tech Member
Joined: Dec 2007
Posts: 593
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From: owensboro, ky, usa
how do you convert o2 voltage to a/f ratio?
just picked up s300 and am new to tuning. im not tuning it ofcourse. im piecing together turbo parts for the future and this was one component and i will not be tuning it. currently im running a stock jdm b16 95 civic and hooked up the s300 just to check it out and mess with the display and check and see how my car was running a little closer. i was using the preset p30 calibration and i dont have a wideband yet but while making a run, my o2 voltage went from .1 at low rpm to 1.0 at high rpm and i dont know if thats good or bad. also dont know what knock should measure but it stays at 5.0. i also noticed that my injectors duty cycle maxes out at 100% right before 8000 rpm and i thought they shouldnt exceed 80%.
like i said im not going to tune it im going to have sean at seendata tune it when i get everything which will be a few months atleast
like i said im not going to tune it im going to have sean at seendata tune it when i get everything which will be a few months atleast
Honda-Tech Member
Joined: Dec 2006
Posts: 996
Likes: 1
From: Portland, OR, USA
Re: how do you convert o2 voltage to a/f ratio?
well my plx m300 tuner edition reads from 0-5v
5 volts should be 10.0:1
0 volts should be 20.0:1
so when stoich is reached you should roughly read 2.5 volts and will fluctuate higher/lower/higher in this fashion. if you have closed loop on, if closed loop is off you should see it stick very close to one voltage.
Read a book.
If your too lean and you try and accelerate you will feel a large hesitation, you can almost hear your car idle good when your at 14.7:1.. play around with it, make small changes, have fun, and make sure you have someone help you if your not sure what changes to make.
I read your post wrong, buy a wideband dont try and rely on narrow band results as they measure only a fraction of air/fuel ratios and will run you into the ground quick.
look at the photo on this page http://en.wikipedia.org/wiki/AFR_sensor
5 volts should be 10.0:1
0 volts should be 20.0:1
so when stoich is reached you should roughly read 2.5 volts and will fluctuate higher/lower/higher in this fashion. if you have closed loop on, if closed loop is off you should see it stick very close to one voltage.
Read a book.
If your too lean and you try and accelerate you will feel a large hesitation, you can almost hear your car idle good when your at 14.7:1.. play around with it, make small changes, have fun, and make sure you have someone help you if your not sure what changes to make.
I read your post wrong, buy a wideband dont try and rely on narrow band results as they measure only a fraction of air/fuel ratios and will run you into the ground quick.
look at the photo on this page http://en.wikipedia.org/wiki/AFR_sensor
Honda-Tech Member
Joined: Mar 2007
Posts: 11,399
Likes: 69
From: East Coast 506, Canada
Re: how do you convert o2 voltage to a/f ratio?
Your running rich. The 1v and 100% injector duty cycle tells you that. You should plug in your stock ECU until you know what it is that you are looking at. You can see and learn a lot about tuning in SManager without driving your car around on an map that is not tuned.
There are quite a few reasonably priced EFI tuning books available to help you learn. There are a couple listed here; EFI tuning Books
There are quite a few reasonably priced EFI tuning books available to help you learn. There are a couple listed here; EFI tuning Books
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