Bugger, the report i have is over the pretty pretty early UK aw11 ecus which didnt appear to run a cat around in the UK, so no additional info about just what the O2 sensor does right here. There are actually as lots of tuning theories as you will find https://4ageblacktopforsale58147.thekatyblog.com/26306422/the-best-side-of-blacktop-20v-4age