Do I need a wideband controller or just a sensor with a megasquirt ecu.

Will this one work?
Link

Yes you do need a controller , that one would work but most people use the innovate LC1 which i think may be cheaper.
Paul.

Yep, the MS system was designed to interface to a narrowband sensor, which basically just swings a voltage one way or the other to say rich or lean. The wideband controller goes in the middle, between the MS and the lambda probe, and will output a precise voltage around the stoich voltage of a narrowband sensor, allowing MS to discern HOW rich or HOW lean the engine is running.

the Wideband controller plugs into a wideband sensor, which has a nice linear (ish) characteristic. It also does something terribly technical with something called a Nernst cell, and it runs a heater to keep the sensor up in its operational temperature regime.

Ed.

How about this one, will it work with Megasquirt?

Link

That has a 0-5v linear output so it should work fine with Megasquirt. It's a very good price too, if you can avoid customs...

http://www.plxdevices.com/products/sm/afr/

[Edited on 22/2/08 by MikeRJ]

Yes, the MS Lambda input is compatible with either a narrow band sensor, or the output from a wideband controller.

I just built my megasquirt, and reflashed it for S&S-E, I'm also using the innovate LC1.
I like the fact that megasquirt is preprogrammed to use the LC1