MS2 with LC-2 and downstream O2
 

I am in the process of installing MS2 basic (Reverant) into my Exocet. Motor is from a California donor 99 miata. Car is currently non-turbo. I'm installing the LC-2, and trying to figure out where to put the wideband sensor. Would it be possible to remove the secondary (downstream) OEM O2 sensor and install the wideband sensor in its place? Or do I have to weld an additional bung instead?

Possible? Yes. Recomended, no.
I take it your on a stock ECU. So weld another bung in.

I just removed the stock ECU and am installing megasquirt along with wideband lc-2. I guess the basic question would be, does megasquirt use the downstream o2 sensor. As a side note, I never plan to revert back to the OEM ECU.

Why not install it in the main o2 sensor bung? Where the first OEM one was.

So as long as the wideband is there, Megasquirt does not use the narrowband O2 sensors (both upstream and downstream)?

Nope, most of the time the wideband is wired into the narrowband pin on the ECU.

Good to know. I will be putting the LC-2 wideband O2 sensor in the OEM secondary location. Thanks for the quick responses.

Again, why not this^?

Good point. Will do this instead.

Behind the cat is totally wrong, if there is still a cat. The values shown will be wrong.

Reverant, can you send me the base map for a stock 99 miata for the ECU you built for me. It is currently running 3.3.2 beta 6.