I have a 2005 grand caravan 3.3l. when driving it seems to have a slight rattle in the engine, once we hit around 43mph it turns to a slight whistle or similar to a high pitched frequency sound. the faster
we drive the more profound it gets. It only does this while giving it gas. I brought it back to the dealer (still under warranty) they say it is just normal drivetrain noise. I find this hard to believe. we love the van but this sound is too annoying.