If it's only a few seconds and sounds like a diesel in the back of your engine, it's probably the cam chain tensioner, due to a worn tensioner or sludgy oil. You can try Seafoam, but if it is the tensioner, it's on borrowed time.

If it lasts for 30 seconds-120 seconds and is coming from the front bumper area, then it's likely the secondary air pump.

 

ok so it threw a code p0012, cam tentioner. I am guess this is what is making the sound. am i right?

 

P0012 is cam position, over retarded. It doesn't directly refer to the tensioner, but it could be caused be the tensioner or a bad CPS. That's a really weird code, I honestly don't think I've ever seen a car throw a P0012.

 

Ya.. prolly CPS..

 

whats a cps?

 

Camshaft Position Sensor....