Re: ITB Conversion on 16 valve 4AGE On my stock bigport AW11 a leaking exhaust manifold gasket brought about the O2 sensor to read lean and it pumped fuel in to the motor. Gas economy plummeted till I sorted it out. Naturally You must run the Map and Iat sensors https://rafaelnljie.get-blogging.com/35188922/not-known-factual-statements-about-4age-20v-itbs