Loud engine noises with 2000 XC70

[Enid Puceflange]

OK, so this has me stumped. The car is normally pretty quiet and civilized to drive, and now suddenly it has gained two new noises. The first one sounds almost like something metal is bouncing off the road below the car - it's a metallic sound. The second noise is more of a resonance - almost as bad as when a coil pack failed, but all cylinders are firing. Both noises are engine speed related, and both go away completely when I put my foot down and accelerate - they are only present on a trailing throttle.

I've checked to see if anything is obviously falling off, and it isn't - and it seems pretty intermittent. I did have a fault code when I pulled them (Turbo control valve) but I didn't write it down, figuring that it was obviously going to throw the code again which it hasn't yet.

So - could the turbo control valve cause this problem? The car has about 135k on it if that's useful. I'm a half-way useful mechanic, and I've not come across a sound like these ones.

[JRL]

Check your front motor mount (right side of the car).
If it's original, the engine is probably sitting on the subframe by now and is resonating all throughout!

[abscate]

Loose muffler, turbo, or cat shield perhaps?

[Enid Puceflange]

Thank you - that's a great idea, which I hadn't thought of. I'll check the engine mount this evening. I'm pretty sure the muffler and heat shield are all OK, because I did wiggle/poke them hunting for the rattle-like-metal-running-along-the-ground