Car become quieter

[Tel]

It's quite a common failure on these back boxes. iIknow of half a dozen or so folk that have had new rear boxes fitted because of rattling/failure of the gate valves.
If one pipe is not sooting up as fast, that indicates lack of flow, which in turn says that the valve is stuck closed and hence quieter.

Whisk it off to the dealer to get it checked out.

[Aitch]

As Tel says.

There are four pipes entering the rear of the silencer box, two on each side. One of each pair has a valve that opens for active or is closed when inactive.

This might help explain. Taken from Jaguar website:

SPORTS CAR SOUNDTRACK
Every F‑TYPE is fitted with an Active Sports Exhaust that creates a race‑car inspired crescendo. The exhaust system reacts to throttle position, speed and engine revs by opening active valves. When open, these valves allow exhaust gases to take a more direct, less restrictive route through the rear silencer producing a much richer, more exhilarating sound. The Switchable Active Exhaust*, allows you to manually open the exhaust valves so you can enjoy F‑TYPE’s stirring soundtrack at all engine speeds.

[shadow_ninja]

Aitch and Tel, thanks so much for replying. Will take yor advice and head to the dealer to get it checked once I read through my warranty paperwork!

[Arne]

I have experienced the same, and it took some time to find the cause.

On my car it was due to two faulty lambda sensors (no error codes in the cars display, but they found it when taking a readout of the car). This resulted in wrong input to the engine management system, which again resulted in reduced pops and crackles - specially when in Dynamic mode.

After replacement of the two faulty sensors, and some driving to make sure the engine management system had adapted to the replacement (that might take some 50-100 miles of "mixed driving") my pops and crackles were back to normal.

Not saying that this is what is causing your "symptoms", but at least it is one of probably several different possible reasons, for why the pops and crackles might be reduced.

[shadow_ninja]

Car now fixed - apparantly it was a failed solenoid, and the dealer just replaced the entire box for me under manufacturer warranty. Not sure why the box needed to be replaced for wht sounds like one part - but it sounds great now, so I don’t really care

[Tel]

Car now fixed - apparantly it was a failed solenoid, and the dealer just replaced the entire box for me under manufacturer warranty. Not sure why the box needed to be replaced for wht sounds like one part - but it sounds great now, so I don’t really care

Good result!

The exhaust gate valves (incorrectly called solenoid by your dealer) are welded into the back box 'in-going' exhaust pipes from the engine into the back box, and cannot be removed, hence whilst it's a new back box.