Over the winter my turbo would not function until the cooling thermostat warmed things up a bit, then it would operate fine. Took it to my independent and he was stumped by it. So I figured summer's almost here.... I'll just keep driving it. Yesterday however the turbo stopped working altogether. Can still get the car up to speed, but it's a little like trying to get a train up to speed. Any ideas on what the problem might be before I race up to the dealership. I do believe the turbo is fine but something is preventing it from activating. 336k miles and still going!