Discussion Starter · #21 ·
Yes, regular is 27% and premium is 25% ( premium is higher octane due to a better base gasoline being used for the mix, not due to ethanol content. Regular is crappy base gas mixed with ethanol which improves the final octane)You guys do have a high ethanol content in your fuel down there don't ya?
Ia have been running on regular since I got the car last year. Previous owner ran it on premium so I got the lean code twice (just don't remember if it was P0171, think it was another code) due to a short term fuel trim being adjusted more than threshold when I filled up with regular for the first time. After clearing that code twice I never had any codes again. CAI went in, and P0171 started appearing. So I don't have much reason to suspect fuel. Just thought the CAI being a bit different in shape and diameter might be throwing the MAF sensor off a bit, and tried filling up with premium to check whether the P0171 code would go away. But it came back.