Northstar Engines and System Technical Discussion Discussion, Bad Mileage And Weird Whoosh Sound in Cadillac Engine Discussion; Hey guys I got a question. I posted the whoosh question in the deville forum but only got 1 response. ...
Automobile(s): Ex-99 Deville owner, Now-04 DTS and 05 DTS. ZX6R Pilot too.
Upper Marlboro, MD
Bad Mileage And Weird Whoosh Sound
Hey guys I got a question. I posted the whoosh question in the deville forum but only got 1 response. Ok I have a 99 Deville. I have replaced the air filter, the sparks plugs(AC Delco), the plug wires, and to no avail. I only get 17-18 mpg on the highway and 9-10 mpg in the city. It sucks! It used to get 25mpg 6 months ago. What else do I need to do to get the mpg up? The engine runs fine and is still quiet and powerful. I haven't noticed any change in engine performance or anything. Also, when I do a WOT, I hear a whoosh sound. The whoosh only comes when the trans shifts from 1st to 2nd. It happens between gears and it happens only when I let my foot off gas in between the gears. If I continually hold the gas, I really can't hear the whoosh. But it sounds a lot like a turbo wastegate opening up and lettin off excess pressure. I had a car with a turbo and it sounded just like it. I know my N* has no turbo. What is that sound? Any help would be appreciated.