Bugger, the posting i have is around the very pretty early UK aw11 ecus which didnt manage to run a cat about in the UK, so no excess data about exactly what the O2 sensor does right here. There are actually as many tuning theories as you'll find tuning outlets. https://jdm-toyota-4a-ge81345.mybjjblog.com/5-easy-facts-about-4age-blacktop-for-sale-described-40364300