2004 buick park avenue
Hey scotty! I have a park avenue with 133k miles. Its been averaging 11-12 mpg, mostly city driving. Ive cleaned a lot of sensors and i have changed some filters. I dont have any codes or check engine lights. Im doing a fuel pressure test tomorrow when i get my gauge, possibly a compression test, depending on what i find. I have never seen this issue with a 3.8 v6! Any advice or help into the right direction would be amazing, thank you! P.S I am hoping its just the fuel regulator but that seems way to easy!
I have cleaned the IAC valve, MAF sensor, I have changed the fuel filter. I did a fuel pressure test today, all seemed good, beside the fuel pressure dropping when i turned off the car. It drops to about 42psi. and when i turn the car off its over 50psi.