: Bad Mileage And Weird Whoosh Sound



99Classillac
01-27-07, 09:08 AM
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.

dkozloski
01-27-07, 03:59 PM
Plugged exhaust system. Maybe you backed into a snowbank and kinked the pipe. Maybe the cat fell apart and pieces lodged downstream. This would also explain bad gas milage.

dkozloski
01-27-07, 06:15 PM
^^^^

99Classillac
01-27-07, 08:01 PM
thanx! now i have an excuse to tell the wife on why i need a new exhaust system!