Well, it's almost impossible to diagnose "annoying ticking sound " over the internet. Especially when "several mechanics look at it and no ne seems to know what causes the sound" - if they can't figure it out, about all we can do is make a few suggestions to be checked out. and I think we have covered them all at this point.

Other than that.............. there really isn't much more that we can help you with on this issue.

 

I'm a couple of years late into this thread but just thought I would mention that my 2011 HRR with 60K miles does the same thing. Ticking only when the engine has been sitting cold over night and only when throttle is applied. No ticking at idle. When driving it goes away if I take my foot off the throttle and coast but I give it a little gas and I can hear it again. And like the OP mentioned it goes away when the engine reaches normal operating temp.

 

Timing chain. And or tensioner.

 

This flutting rev sound/ tic at idle turned out to be a broken whisker on the #3 spark plug, which I discovered a couple months after posting this video.

 

Thank you Aradmahagony.


I never heard the term spark plug "whisker" before. Can you explain?

 

He's referring to the center electrode, quite small on these iridium plugs.

 

It's small but zaps a whole lot of voltage!! That's why we highly recommend to never touch it with a gapping tool

 

How are these type of spark plugs gapped? I am used to the traditional wire gap gage that would require some electrode contact.


Thanks again

 

They are gapped at the factory and shipped with protective sleeves.

 

Yes. I never touched or attempted to change the gap, but somehow it broke off anyway. The whisker is that hook looking part. I think that spark plug had a hard time during shipping; the replacements have been perfect. Anyway, that same issue caused an odd foghorn/clown horn phenomenon through the EVAP system, that was rectified when I replaced the bad plug. Amazingly, the car ran, revved, and performed perfectly with the bad plug in there. These engines are amazing.
Foghorn/clown horn for reference.