Is target voltage set from Narrowband or WB

peasly23 · Post by **peasly23** » Mon Oct 08, 2007 8:06 am

When setting my target voltage for 14.7 in closed loop operation, do I set the target voltage to be stoich on my narrowband (.45 volts) or stoich on my wideband (2.46 volts)?

Here's what I run...

Permanently Installed Innovate LC1 using simulated narrowband, a.k.a, no other O2 sensors but this one.
Wideband voltage = (0V = 7.35 AFR and 5V = 22.39)
Simulated Narrowband voltage = (1.1V = 14 AFR and .1V = 15 AFR)

Post by **Hondata** » Mon Oct 08, 2007 9:32 am

Closed loop runs off the narrowband input.

peasly23 · Post by **peasly23** » Mon Oct 08, 2007 9:52 am

Ok, seems simple enough. Thanks for the concise answer.

Based on the data I gave, does anyone know if the simulated Narrowband output voltage (1.1V = 14 AFR and .1V = 15 AFR) is in fact the correct voltage to simulate a narrowband O2 sensor on a P28 ECU? Just wanted to verify.

Thanks again!

Post by **Spunkster** » Mon Oct 08, 2007 10:32 am

The narrowband output should look like this:

peasly23 · Post by **peasly23** » Mon Oct 08, 2007 4:02 pm

Ok, so based on that, are you saying I should reprogram my simulated narrowband LC1 to match that diagram?

I can do that, but is there anything more exact than "somewhere between .9 and 1.0 for RICH and .0 and .1 for LEAN" that I should reprogram it too?

Post by **Spunkster** » Mon Oct 08, 2007 4:32 pm

That graph is exatly what a Honda ecu is looking for from a narrow band sensor.

peasly23 · Post by **peasly23** » Mon Oct 08, 2007 6:41 pm

Maybe you missed my question...

peasly23 wrote: ... is there anything more exact than "somewhere between .9 and 1.0 for RICH and .0 and .1 for LEAN" that I should reprogram it too?

That graph isn't exactly accurate if you know what I mean.

Post by **Spunkster** » Tue Oct 09, 2007 9:25 am

This is why we recommend the PLX as it has both narrowband and wideband outputs and are not adjustable by the user.

You can get any more exact than what that graph shows. Those are the exact characteristics of a stock narrowband sensor.

peasly23 · Post by **peasly23** » Tue Oct 09, 2007 3:13 pm

Ok, I think I understand what is going on here... Ponder this for a second, then let me know what you think...

I don't think the ECU, with or without the Hondata installed, cares what the top and bottom range of the voltage is. All it cares about is what the voltage should be, at Stoich. In the case of your posted (and well known) graph, all that matters is the .50 volts and it being able to adjust above or below this value as rich/lean conditions exist.

I think that the only reason the 0 to 1 volt range even exists is just by the very nature of a Narrowband O2 sensor, that it only can output between 0 and 1 volts, with it being particularly sensitive around stoich, or .5 volts.

So, with that being said, I believe any voltage range can be used, whether it be a PLX or LC1, or etc, etc, so long as you know at what voltage stoich is. So, in my case, the simulated narrowband outputs between .1 and 1.1 volts, but stoich is @ .45 volts, as long as we know this, we shouldn't have any problems running in closed loop, so long as we have the correct target voltage set.

Otherwise, you wouldn't have a feature called "target voltage" in which we can set at stoich for our particular Narrowband sensor or output, whatever it may be.

Does this make sense? I feel like it is a breakthrough that allows us tuners to understand what is going on better. Or if it's completely off base, at least it's here to be searched & researched for future tuners to understand better.

Thanks for your time.

Post by **Spunkster** » Tue Oct 09, 2007 4:23 pm

It cannot be a linear signal, it must be a narrowband signal that exactly mimics the stock sensor like the graph i have posted.

The ecu adjusts fuel trim based on the narrow band voltage input and then makes calculation based on that voltage to calculate how much injector duty cycle to add or subtract. By changing the characteristics of the input voltage you make the adjustments get way off and you will find your car running excesively rich or lean in closed loop.

We know what works and know why, and this is why we ONLY recommend the PLX Devices widebands.

peasly23 · Post by **peasly23** » Tue Oct 09, 2007 4:31 pm

Ok, I understand what you are saying and will contact PLX to research some more information.

What about what I said here though...

Otherwise, you wouldn't have a feature called "target voltage" in which we can set at stoich for our particular Narrowband sensor or output, whatever it may be.

Why then do you give us this option to change the target voltage then? Just out of curiosity.

And thanks for the discussion by the way. That's what this tuner community is all about. Discussing and learning.

peasly23 · Post by **peasly23** » Tue Oct 09, 2007 4:35 pm

Oh, and I forgot to ask... how come we can't set the target voltage to exactly .50? When I do, it changes to .51.