I can only hear this with the hood up. Its a tapping sound that starts soon after i start the car cold. It starts slow, then speeds up faster and faster with the car just idling. If I rev the engine a tad, the tapping frequency goes back down (to the same frequency as say the cow-bell in the song they made fun of in that one SNL skit "I need more cow-bell!" - Christopher Walken) and very slowly picks up.

Any iders?

 

lifter tap?

 

Is it coming from the airbox? It might be the EVAP canister purge regulator valve and yes it's suppose to make a clicking sound.

 

heh i have the same problem...its very annoying

 

Does it go away when the car warms up?

Does the speed of the tapping increase with the RPMs?

 

When my wastegate valve was broken it only ticked when the Turbo was in use, so you can check that off your list most likely. Misfireing is my only idea, how recently have you changed your sparkplugs?

 

Thanks for the ideas, very much appreciated. To answer questions, yup, this happens with the engine cold or warm. Not misfiring i don't think, the engine runs really, really smooth. I'll try tommorrow to figure out whether it increases with engine speed, I didn't think of checking that yet. Thanks again, ill update tomorrow.

 

What year and engine is your car? Does it sound like a diesel?