The Ford 3.5L Ecoboost engine is a marvelous design, out performing the ledgendary Coyote while being the premiere engine in the F150 and Expedition line-up, as well as being used in more performance oriented vehicles like the Taurus Sho, Police Interceptor, and Raptor. But even such a well established engine has had several reoccuring issues...
The 3.5L EcoBoost is great engine with a few problematic complaints. These engines come buried inside the F150, Explorer, and Taurus have been experiencing little growing pains. I mean that literally - the timing chains are stretching causing all sorts of problems. A stretched chain causes a few drivability issues, maybe some noise, then escalates into a full blown tear-down due to bent valves. See the picture? No good! I love these 3.5L EcoBoost engines, but this is definitely an issue...
We have all seen the people talk about premium fuel as if its worthless additional cost that has no benefits, while others are conned into thinking adding premium fuel to a economy engine is going to result in a cleaner injectors and more power. The truth is that premium fuel definately can contribute to increased power, both with aftermarket and factory tunes. Ford has chosen to deal with this with something called the octane adjustment ratio...