Hey Scotty! greetings from Los Angeles! I have an '07 Toyota Matrix that was previously giving me a P0171 lean code and running at positive 20% LTFT at idle and positive 25% under load. I went through everything and put in a new PCV valve, new manifold gasket, new Denso MAF, new air filter, new DENSO fuel pump and pressure regulator, and -after all that didn't fix the lean problem- I even got new Beck/Arnley fuel injectors. Now, even though my Matrix has is running great and I gained and extra 4mpg, it is running rich at negative 18% ltft at idle and negative 22% under load. I've asked a few mechanics and they're stumped. What Would Scotty Do?
Well You're getting better gas mileage. Wish you should be happy with. Realize that fuel trims change all the time and a lot of the machines that read them are not all that accurate. If you do get good, gas mileage in the car runs fine. I personally wouldn't even worry about it. Just realized many '07s had a recall for the main computer and maybe the circuits are getting a little wacky and giving out bad data
