Quote: the one thing that been eaten at me was the concept that fi was suppose to give better performance and fuel mileage over a carb what gives?? I would love to get alittle more fuel mileage out of my 99 p/u 318 auto. What about installing taller tires wouldn't that help fuel mileage?
The problem is peak fuel efficiency isn't always the cleanest burn. The tailpipe has to put out limited amounts of... whatever comes out the tail pipe, and leaning it out for best mileage can jack that up. Also, it seems to me that the pre-magnum TBI motors got better mileage, but the lean condition led to cracked heads over time. Taller tires should help with cruise mileage if the combo is right, but it'll affect acceleration. Skinnier tires will help with rolling resistance.
