2013 XF 3.0SC 72k
I started having this stumble/rpm fluctuation at high gear low throttle, I checked my long term fuel trims at idle, parked, hot and noticed they were both approaching 17-20 percent positive/lean on bank 1 and 2. No misfires and trim goes down with more RPM.

I replaced the PCV diaphragm. This is tricky but its 100 percent doable with the supercharger in the way. Remove the cowling and break off 4 of 6 tabs with a pick CAREFULLY. Then you can lift the cap and rotate it out. Use a zip tie to hold the spring and get it back in. Cut the zip tie and verify the spring is seated correctly top and bottom before pressing it down to click. You can then visually verify with a mirror that 5/6 of the tabs are fully seated. A borescope can be used for the 6th under the supercharger. Use every precaution to not break the retaining tabs on the valve cover.

My diaphragm was not torn completely through yet but did have some light tearing. My fuel trims did not change after this.

I purchased a smoke machine and two intake bladders to seal both intakes and tested the vehicle injecting the smoke from the passenger side.

I noticed no leaks other then the intake tube itself. Minor leaks coming from both the passenger tube and throttle body connection but a LARGE leak coming from the driver side tube. No amount of torque or reseating can fix it. Visually I can see nothing wrong with the tube. It was purchased May 2022 from a dealer but after I installed it I noticed it was old stock, 2017 mfg date.

I talked to a JLR tech who told me some minor leakage from the intake connection points is normal but it seems my intake is defective, any thoughts?

I also had my purge valve disconnected at the fuel tank side during smoke test and verified the valve is good, with no power its closed.

Smoke test below

Thanks

 

I duct taped the joints and went on a 18 mile test drive.
For the first half I had significant decrease in long term fuel trims, then all of a sudden the went back to the way they were. Not sure if the duct tape got hot and loosed up.



Duct tape on joints

First half of test drive

Second half