cool. i didn't know that. i thought the ecu was controled by the o2.

 

On my standalone, there is an option where you disable the O2 sensor feed back to the computer, which is how mine is currently setup.

 

They really don't do a HUGE amount until OBDII (late 95+). Thats when they went to multi-wire multi-o2 setups. Usually one upstream near the manifold that the ecu bases short-trim fuel off of. And a second more downstream right after the cat, that basically is emissions based and lets the car know how the cat is or isn't working. And most OBDII cars at WOT just go off of preset fuel maps and the o2's input to the ecu is ignored.

 

on the 2nd gen the open loop ( when its reading the 02) is only for light throttle between about 2500-3800 rpm