I've started hearing a 'fluttering' sound on acceleration but only when my engine is cold. After 10 or so minutes of driving the sound is not there anymore. Dealer kept the car overnight but of course everything is normal sounds to them so it's up to me to narrow down the culprit and I need some suggestions.
The best way I can describe it is a muffled sound of a card in a bike spoke (very different from a tick). Noticeable in the cabin if the radio is turned down. Very noticeable as I drive by walls, other cars and it bounces off.
I first noticed it within a week or so after dealer replaced my leaking oil pan gasket. Maybe coincidence but also wondering if the oil pan removal procedure has anything where they unbolt any part of the exhaust? Possible exhaust leak?
Oil life and levels are good.
Car is a 2009.1 w/ 64k miles, is my daily driver, and is all stock except for the Rotofab intake.
I do not notice any difference in how it drives.. seems to have same power, response, etc...
Any ideas?
I am the original owner and still have till Feb 2015 on my GMPP extended warranty so any input I can get to narrow this down to something that should be covered and I can get the dealer to recognize is much appreciated. Even if it turns out to be something not covered I'm fine with that too just need to get this taken care of.