Wideband values
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Evolving Member
Joined: Oct 2012
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From: North AL
Wideband values
Pardon the super noob question... I get the basics of wideband and what stoic, rich and lean conditions are. But.. in terms of actual values on the X, what is considered too rich and what is considered too lean? I ask since I'm trying to configure my wideband guage and I'm having comprehension issues 
14.7 : 1 is stoichiometric mixture of parts air to parts gasoline for GASOLINE (that part is important).
10:1 is rich, because it's less parts air to 1 part gasoline
20:1 is lean, because it's more air to 1 part gasoline.
That's generally the range of most gauges.
Here's the important part. Stoichiometric (ideal) is only theory ideal, in practice it's generally too lean while under load.
Turbocars tend to be happiest around 11.4 - 11.7 ( :1), Natural aspiration can generally be pushed to around 12.5 -13.1 all dependant on timing given.
So basically the gauge is going to oscillate back and forth, because your O2 sensor is going to be reading the the car idle or cruise and the timing and injectors are going to be changing. This is normal.
What's important is making sure that at idle it's only bouncing around 12 - 16ish... if it's going to 17-20 and staying there during idle you're probably having an issue.
--> This is the important reason why as an Evo owner you want a WB AFR gauge.
When under Wide Open Throttle and making boost, you want to see your AFR no leaner than 12:1 (or whatever value your tuner tells you)
Factory tune you might see it around 10.x. If you're tuned you'll want to ask your tuner what they were targeting for, but I bet it will be 11.4 - 11.9 ish.
Hope that helps
10:1 is rich, because it's less parts air to 1 part gasoline
20:1 is lean, because it's more air to 1 part gasoline.
That's generally the range of most gauges.
Here's the important part. Stoichiometric (ideal) is only theory ideal, in practice it's generally too lean while under load.
Turbocars tend to be happiest around 11.4 - 11.7 ( :1), Natural aspiration can generally be pushed to around 12.5 -13.1 all dependant on timing given.
So basically the gauge is going to oscillate back and forth, because your O2 sensor is going to be reading the the car idle or cruise and the timing and injectors are going to be changing. This is normal.
What's important is making sure that at idle it's only bouncing around 12 - 16ish... if it's going to 17-20 and staying there during idle you're probably having an issue.
--> This is the important reason why as an Evo owner you want a WB AFR gauge.
When under Wide Open Throttle and making boost, you want to see your AFR no leaner than 12:1 (or whatever value your tuner tells you)
Factory tune you might see it around 10.x. If you're tuned you'll want to ask your tuner what they were targeting for, but I bet it will be 11.4 - 11.9 ish.
Hope that helps
Last edited by TheBlade; Nov 17, 2012 at 02:17 PM.
Thread Starter
Evolving Member
Joined: Oct 2012
Posts: 165
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From: North AL
That does help a little, though I'm still trying to digest the information
I'm basically trying to configure this screen:
So, as you can (hopefully) see, that lets me set the max (and min) wideband values for specific boost values.
If I'm understanding you correctly, I should set the max to be no higher than 12-ish at boots (0+), but it can be up at 18 for <0, correct?
I'm not sure if the tuner set my gauge or not, but it did have a curve similar to the one you see in that screenshot. Problem is, I was blowing the alarm when accelerating in 5th (so under load) so I think it was set too low. I have since accidentally reset the graph, so I have to start from scratch.
I'm basically trying to configure this screen:
So, as you can (hopefully) see, that lets me set the max (and min) wideband values for specific boost values.
If I'm understanding you correctly, I should set the max to be no higher than 12-ish at boots (0+), but it can be up at 18 for <0, correct?
I'm not sure if the tuner set my gauge or not, but it did have a curve similar to the one you see in that screenshot. Problem is, I was blowing the alarm when accelerating in 5th (so under load) so I think it was set too low. I have since accidentally reset the graph, so I have to start from scratch.
14.7 : 1 is stoichiometric mixture of parts air to parts gasoline for GASOLINE (that part is important).
10:1 is rich, because it's less parts air to 1 part gasoline
20:1 is lean, because it's more air to 1 part gasoline.
That's generally the range of most gauges.
Here's the important part. Stoichiometric (ideal) is only theory ideal, in practice it's generally too lean while under load.
Turbocars tend to be happiest around 11.4 - 11.7 ( :1), Natural aspiration can generally be pushed to around 12.5 -13.1 all dependant on timing given.
So basically the gauge is going to oscillate back and forth, because your O2 sensor is going to be reading the the car idle or cruise and the timing and injectors are going to be changing. This is normal.
What's important is making sure that at idle it's only bouncing around 12 - 16ish... if it's going to 17-20 and staying there during idle you're probably having an issue.
--> This is the important reason why as an Evo owner you want a WB AFR gauge.
When under Wide Open Throttle and making boost, you want to see your AFR no leaner than 12:1 (or whatever value your tuner tells you)
Factory tune you might see it around 10.x. If you're tuned you'll want to ask your tuner what they were targeting for, but I bet it will be 11.4 - 11.9 ish.
Hope that helps
10:1 is rich, because it's less parts air to 1 part gasoline
20:1 is lean, because it's more air to 1 part gasoline.
That's generally the range of most gauges.
Here's the important part. Stoichiometric (ideal) is only theory ideal, in practice it's generally too lean while under load.
Turbocars tend to be happiest around 11.4 - 11.7 ( :1), Natural aspiration can generally be pushed to around 12.5 -13.1 all dependant on timing given.
So basically the gauge is going to oscillate back and forth, because your O2 sensor is going to be reading the the car idle or cruise and the timing and injectors are going to be changing. This is normal.
What's important is making sure that at idle it's only bouncing around 12 - 16ish... if it's going to 17-20 and staying there during idle you're probably having an issue.
--> This is the important reason why as an Evo owner you want a WB AFR gauge.
When under Wide Open Throttle and making boost, you want to see your AFR no leaner than 12:1 (or whatever value your tuner tells you)
Factory tune you might see it around 10.x. If you're tuned you'll want to ask your tuner what they were targeting for, but I bet it will be 11.4 - 11.9 ish.
Hope that helps
Sounds about right, however your AFR is dictated more by load. I mean its load to make boost, and adding boost adds load.
I think what your saying is correct, however for low values of boost you might have your AFR still diving from 15ish to 11ish. So, for purposes of the failsafe You'll want to probably say no higher than 12 once you're over 10psi rather than 0psi.
And when it oscillates it can actually go up to 20 when you engine brake. So the time above 18 you might want to consider it to happen for a few seconds.
You'll probably want to set it with that, and then adjust as needed.
I think what your saying is correct, however for low values of boost you might have your AFR still diving from 15ish to 11ish. So, for purposes of the failsafe You'll want to probably say no higher than 12 once you're over 10psi rather than 0psi.
And when it oscillates it can actually go up to 20 when you engine brake. So the time above 18 you might want to consider it to happen for a few seconds.
You'll probably want to set it with that, and then adjust as needed.
Thread Starter
Evolving Member
Joined: Oct 2012
Posts: 165
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From: North AL
Ok, now I'm comprehending! Thanks, I'll start with that and log some data to see what's happening. Much appreciate the help
Sounds about right, however your AFR is dictated more by load. I mean its load to make boost, and adding boost adds load.
I think what your saying is correct, however for low values of boost you might have your AFR still diving from 15ish to 11ish. So, for purposes of the failsafe You'll want to probably say no higher than 12 once you're over 10psi rather than 0psi.
And when it oscillates it can actually go up to 20 when you engine brake. So the time above 18 you might want to consider it to happen for a few seconds.
You'll probably want to set it with that, and then adjust as needed.
I think what your saying is correct, however for low values of boost you might have your AFR still diving from 15ish to 11ish. So, for purposes of the failsafe You'll want to probably say no higher than 12 once you're over 10psi rather than 0psi.
And when it oscillates it can actually go up to 20 when you engine brake. So the time above 18 you might want to consider it to happen for a few seconds.
You'll probably want to set it with that, and then adjust as needed.
I really wanted to get the failsafe when I first saw it, then I found that the boost sensor is integrated into the gauge itself and you need to run the plastic line all the way to under the hood. I hate those. So I decided to just go with boost and AFR separate
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Thread Starter
Evolving Member
Joined: Oct 2012
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From: North AL
I took the easy route and just had English Racing install it. They recommended the setup and I like the data logging and alarming features. I don't actually have the failsafe hooked up to anything, though, but I suppose it could be in the future. The gauge flashes when the alarm is triggered, which is enough for now. A little buzzer would be nice for the failsafe for now.
Yeah, from how I understood the gauge, it would be easy to hook up to a 3port and if you run lean would drop you to wastegate pressure.
It would be like a smarter limp-mode. Sounded like a great idea.
It would be like a smarter limp-mode. Sounded like a great idea.
Thread Starter
Evolving Member
Joined: Oct 2012
Posts: 165
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From: North AL
The failsafe triggers a ground wire.. how would that work with a 3-port? I'm asking since it sounds like what I'd want and I'm still a little clueless.
I would need to look up the wiring diagram, and then verify with a DVOM, but I believe the solenoid is fail-safe. So if you ground the solenoid circuit it falls to bypass mode and you'll only run waste-gate pressure.
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From: Louisiana
LOAD LOAD LOAD determines the desired a/f ratio. If youre cruising light load as high as 17:1 is fine and used on a lot of stock cars tunes.
I have a feeling 99% of tuners are half assing/ extrapolating the tunes for the partial throttle tables on the evo causing all the blown motors we see on this forum. I dont see how you can tune the partial throttle values reliably and safely for varying load, throttle positions in the 1 or 2 hours people are paying for.
I have a feeling 99% of tuners are half assing/ extrapolating the tunes for the partial throttle tables on the evo causing all the blown motors we see on this forum. I dont see how you can tune the partial throttle values reliably and safely for varying load, throttle positions in the 1 or 2 hours people are paying for.
Thread Starter
Evolving Member
Joined: Oct 2012
Posts: 165
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From: North AL
Well, I think that is a question you could ask the tuners. I feel pretty confident about the English tune I have, I don't think any part of it has been half-assed.
LOAD LOAD LOAD determines the desired a/f ratio. If youre cruising light load as high as 17:1 is fine and used on a lot of stock cars tunes.
I have a feeling 99% of tuners are half assing/ extrapolating the tunes for the partial throttle tables on the evo causing all the blown motors we see on this forum. I dont see how you can tune the partial throttle values reliably and safely for varying load, throttle positions in the 1 or 2 hours people are paying for.
I have a feeling 99% of tuners are half assing/ extrapolating the tunes for the partial throttle tables on the evo causing all the blown motors we see on this forum. I dont see how you can tune the partial throttle values reliably and safely for varying load, throttle positions in the 1 or 2 hours people are paying for.
I have a question about reading the gauge cause I have no experience with this stuff.
So at idle my reading hovers around ~14 - ~15.7, which is right under what the first response suggested.
When accelerating on constant throttle, the number keeps jumping back and forth at the same rate from ~13 - ~15.7. Is it suppose to be changing at such a constant rate under throttle?
So at idle my reading hovers around ~14 - ~15.7, which is right under what the first response suggested.
When accelerating on constant throttle, the number keeps jumping back and forth at the same rate from ~13 - ~15.7. Is it suppose to be changing at such a constant rate under throttle?
Last edited by kzlflash; Nov 21, 2012 at 08:23 AM.
If you're not under wide open throttle, only partial, you should see it oscillate a little. That's because a leaner burn will yield more efficient power, however you're ECU is smart enough to see a lean mixture and add more fuel.
The 1st O2 sensor in your exhaust, is actually a wideband. (the quality may/may not be what the aftermarket one you bought). But it's what the ECU uses to adjust your fuel trims.
Also, you may see your mixture look a little lean under just a few pounds of boost or rpms lower than like 4k revs. That's normal, because you're car isn't into the heavy load tables of it's fuel calculations yet.
The most important part of a WB AFR gauge is to watch your AFR when you have the pedal stomped and your in some heavy boost. That's where a lean burn could cause detonation that will destroy your engine.
However, it's good that you notice what it's doing under partial throttle. If under partial throttle you suddenly see it going to like 17.0-20.0 You'll know something isn't working right and can start doing some investigating.
The 1st O2 sensor in your exhaust, is actually a wideband. (the quality may/may not be what the aftermarket one you bought). But it's what the ECU uses to adjust your fuel trims.
Also, you may see your mixture look a little lean under just a few pounds of boost or rpms lower than like 4k revs. That's normal, because you're car isn't into the heavy load tables of it's fuel calculations yet.
The most important part of a WB AFR gauge is to watch your AFR when you have the pedal stomped and your in some heavy boost. That's where a lean burn could cause detonation that will destroy your engine.
However, it's good that you notice what it's doing under partial throttle. If under partial throttle you suddenly see it going to like 17.0-20.0 You'll know something isn't working right and can start doing some investigating.
