I would start by checking the fuel trims at idle, and then further under that medium acceleration. Remember, trims are a function of load and rpm, so there is more of a trim matrix. If you use TorquePro with an ELM327, there is a record function to help you keep your eyes on the road. Trims trip an OBDII code at 25%, but there is nothing good above, say, 5%.

FWIW, XKR folks frequently report cracks and air leaks where the Helmholtz resonators attach to the main intake tube. Might be worth double checking those areas. Generally though, you are better off doing a smoke test for high trims.

Best of luck, keep us posted.

 

Is it worse going up hill?

 

Thank you. On air leaks, how about simply replacing that tube with a larger diameter non resonator tube?

 

The debate is that the stock resonators are there to preserve the intake air flow for some frequencies created by the supercharger. Without them, these sound waves can combine with themselves and reduce flow. Jaguar engineers thought they were necessary/helpful because they didn't simply re-use the XK8 design. I believe intake resonators are standard practice for engines with a supercharger. In practice, my take is that the straight tube tends to amplify the turbine/jet/supercharger part of the noise an XKR makes under acceleration.

On the plus side, these metal tubes tend to be a one-time install with "infinite" life, well beyond what a plastic accordion could ever deliver.

 

Honestly a little little extra "Noise" from the quiet engine may not be a bad thing. Lol. Also, I've been told that pipe, box etc is woefully inadequate for the 4.2 supercharged as like you said it was based upon the earlier non super charged XK8.