Negative means it is pulling fuel, you want to err on the rich side. I did not mess with factory tune. Those are short term fuel trims. Onve I get the pulley on I am going to have it dyno tuned on a load bearing dyno. I have not checked fuel trims since my K and N drop in and high flow down pipe and resonator delete. I don't believe a dirty throttle blade has anything to do with it. Case relearn makes sense and iim gonna swap out control modules as I have a spare along with lots of stuff for test parts.
