My car has a strange idle. Especially when the outside temp is cooler. I sounds like it has a big cam, or more distinctively Like a happy cat purring. Seems to have no effect on performance, doesn't stall, no apparent vacuum leaks ( I'm about to do a leak test too ) and never a code. Its very rhythmic and consistent, and to be honest I like it, and it gets some real strange looks, but that being said, Id like to know whats causing it. Anyone else get this ever? Oh, its an 08 LNF.

 

The cold weather makes the car louder of course. Stock exhaust?

 

U mean it sounds like a frog with a loud clock beside it? If that's what u hear that normal.

 

Catted down pipe, 3" resonated straight back to Magnaflow muffler. Not a case of louder because of cold. Im sending a Log to John to try to figure it out.

 

You sure it's not cat warm up?

 

Vaccum leak

 

This. Sounds like you need to do a boost leak test. See sig.