because narrowbands output a bunch of nonsense; I'm not even sure you can consider tuning on a nb sensor, tuning.

Maybe I misread.

but yes, there's still an advantage to always running a WB sensor.

No I meant with a wideband. Say you got MS and a wideband but otherwise stock nb, would you pick up the 10-15hp the na's tend to pick up otherwise stock?

nb, in my case = narrowband.


of course youll pick up power tuning an NA, NB, NC miata running MS.

lol abbreviation phail.

Yes, you can run closed-loop from a narrowband sensor, but only at 14.7 : 1. Wideband is required to run closed-loop at richer or leaner mixtures than 14.7 : 1.

This is not correct.

The term "closed-loop" in the context of an EFI system means that the ECU uses the reading from the O2 sensor to adjust the amount of fuel delivered, seeking to achieve a specific target mixture.

If no O2 sensor is present, then the system cannot, by definition, operate in closed-loop mode.

OOOPS! My bad, I meant to say open loop. Thanks for catching that. This thread is full of bad communication.

OK, I ended up with 3 oxygen sensor in the exhaust. 1 wideband and two OEM narrowbands. This should be OK as far as I can tell? MS should be just ignoring narrowband signals, right?

If the narrowband sensors are not physically connected to the MS, then it will obviously ignore them. (It's not telepathic.)

If the narrowband sensors are connected to the MS, then it may or may not ignore them, depending upon the configuration of the software.

They are physically connected through the harness to MS.

In Tuner Studio I've set "Wideband" for Oxygen sensor in the original configuration. Should this be enough to ignore the narrowand's signals?

lol. you have much to learn.

You think? :)

Seriously, I am trying to learn. Any help would be greatly appreciated.

You haven't told us anything about your car, its wiring, which MS you are running, etc.

Is this, for example, an MSPnP or a regular MS?

If so, then by default the stock forward O2 sensor is connected to the MS.

If you have added a wideband, we'll need to know how that's wired and what, if anything, you did to disconnect the narrowband sensor from the MS.


The software selection for narrowband vs. wideband cannot cause the MS to physically look at one sensor vs. another- it simply describes to the MS how it should interpret the one O2 sensor signal which it sees.

Joe, the car is '2000 normally aspirated. I'm running Dimitris (Reverant) built MS PNP for '99-2000 Miata (last group buy).

The wideband is connected through LC-1 so I assume (incorrectly?) that MS reads it on a different pin than it would read a front OEM O2 sensor. I did nothing to disconnect the stock O2 narrowband from the stock harness. I am not sure that Dimitris' MS PNP is actually reading the narrowband sensor at all.

You'll need to contact Reverant directly on that.

A "normal" MS has only one O2 sensor input pin, which is used for either a wideband or a narrowband, depending on the wiring.

I know that Reverant's MS's are a bit different and the wiring package which he supplied will determine what is connected to what. It's probably safe to assume that his wiring package ignores the narrowband sensors entirely and has connected only the wideband.

Joe, thanks! I exchanged emails with Dimitris and he suggested shorting O2 heater ground supplying pins from ECU (1U and 3V as far as my manual tells me) to the ground in the harness.

Just so this might help someone in the future:

O2 sensors in at least '99-2000 cars get their +12V to the heaters directly from ignition (BlackWhite wire in O2 sensor harness). Ground, however, is supplied by ECU on aforementioned pins 1U (front sensor) and 3V (rear sensor). Tying the heater ground wires (Purple/White for the front sensor and Red/Yellow for teh rear sensor) to Ground would effectively keep the heater circuits on whenever the car is on.