My 04 XJ8 has been running lean with the 0171 and 0174 codes set with misfire on all cylinders of bank 1. It runs rough when cold and smooths out when warm.

Perhaps related but it has a drone/vibration in top gear when accelerating under load; mostly from 70 mph up.

Anything that would cause a single bank to act lean like this?

LTFT

Bank 1: 0 - 9.4 %
Bank 2: -0.8 - 7 %

 

"Perhaps related but it has a drone/vibration in top gear when accelerating under load; mostly from 70 mph up."

Possible transmission mount:

https://www.jaguarforums.com/forum/x...cement-150290/

Less possible: jurid coupling

 

I also suffer from leaning. On cold weather I have P0171. Car feels lazy.. Please advise where to start looking for problem.













Recently installed full new exhaust not affected issue at all.

 

Transmission mount was replaced and had failed. Motor mounts? I checked the engine movement in park and reverse and it did lift a bit but not a very quantitative measure.
I looked at the flex coupling driveshaft joints and did not see visible signs of failure.