wideband sensor

why a wideband sensor isn't used in EFI systems instead of narrow band?

If you mean on OEM applications, it's because the tunes - ignition, fuel, etc. - are set at the factory for each vehicle and the narrow band is just there to correct for things like injector variations, wear, build up of deposits on the injectors, etc. to pass the various emission standards where they're sold.

There isn't any reason for them to fit wide-band, which is usually more expensive, anyway.

Thank you, Gord.

I appreciate it.