So on Friday I started to hear a new unwelcome sound from the car.

1. Around 1,300rpm while accelerating from creep/stop i hear a scraping/rattle sound which sounds like it's coming from underneath the car just to the right of the transmission stick area in the cockpit. It lasts for about 1 second and does not return unless similar conditions are met (stop/creeping and accelerating past 1,300rpms).
2. On Saturday I then noticed what sounds like something is 'loose' from the same area when going over a big enough bump in the road.
3. I started getting more overrun pops/bangs in Normal driving mode (active exhaust open). Typically when letting off the pedal I did not get these sounds unless the Transmission was in Sport.
4. I could be crazy, but I swear there was more industrial noise present before (hearing more going on in the engine bay - extra belt sounds, etc). Now at a stop it's practically dead quiet.

I should note, I drove a friend home on Thursday with music off the entire time, so these noises would definitely have been noticed if they were present before hand.

Anywho, appointment with the mechanic booked for Tuesday morning, so we shall see!

Also getting fairly frequent Gearbox fault/CEL warnings, that disappear after 4 starts of the car or so. As i read this is not an uncommon 'glitch' and it is clearing itself at a normal rate, I've left it for now. I'll have him pull the codes/poke around and see what's what.

Otherwise if anyone has a guess or some insight I'd love to hear it.

 

I think you're going to need to get under the car to isolate the cause, but that it should be fairly obvious once you do.

Metallic rattling noises are often loose heat shields that resonate at specific engine speeds. Another possibility is that you've got a broken matrix inside one of the cats. After a quick visual inspection and poking at things by hand to check for looseness, I'd then tap on the exhaust on or near the cat with a rubber mallet.

 

Got off work early so I dropped by the mechanic today. Went for a drive together and he heard everything i wanted him to. Initial impression is he's confused, but he will obv. know more when he gets it up, as you say.

 

Well thankfully it was an easy fix. As per the mechanic one of the plates under the car had shifted and was resting against the exhaust. The vibrations cause by throttle input were what was causing the noise, but man..weird sound.

He also did a software update for the Gearbox errors, we shall see!

Back in action!