Truck makes grinding noise at cold start. After about a mile of travel sounds like impeller of turbo is grinding, then goes away. Ford says they can't duplicate noise, said it's spark knock. I know what spark knock is and this is not it!! Its starting to do it more and for a longer period of time. The Ford advisor told me there's plenty of warranty left to just let it blow up and they will put a new motor in my $50,000 truck!!!! Its bull crap! and that's not even complaining about the jerky transmission!