Strange noise on acceleration and shifting.

[DocL]

Lately I've been hearing a "pffft" sound when I shift from 1st to 2nd above 6000rpms. It almost sounds like there is an air leak from somewhere in my engine. This has even happend while I'm accelerating in second gear to redline. There's no hesitation in acceleration, and I'm up to date on my service. I am going to have the plugs and 60k service done soon (I'm at 48k on the odo now). I have a K&N air filter, but it's been in my car for 20,000 miles with no issues.

Any guesses as to what this noise may be? It sounds like a vacuum hose leak, but how do I figure it out while driving?

-TIA

 

[docjohn]

Have you had the K&N fiter cleaned lately?I get more whistling or pffting just after cleaning my uni filter.

 

[DocL]

Have you had the K&N fiter cleaned lately?I get more whistling or pffting just after cleaning my uni filter.

I don't think it's from the K&N. I always notice the whistling sound under acceleration but I only hear the escaping air sporadically. It sounds like compressed air is escaping a cylinder and only under the two situations described before.