Hi,
I have another issue with my XJ12: on cold-start everything is running fine and smooth, also when driving for longer time, but when I stop the engine for let's say 10 or 15 minutes and then restart it, it is vibrating very explicitly, idle rev is only about 600 RPM. It's probably not running on all cylinders, even sounds odd at the exhaust. But it accepts gas without problems, above 1000 RPM vibrations are hardly recognizable, but probably still not running on all cylinders. After some minutes of driving it becomes better, but I cannot exclude that maybe 1 or 2 cylinders are still missing.
I had it checked at my Jag specialist, but he could not find an issue, spark cables and plugs are ok. He assumes it's the fuel injectors, some of them may be clotted due to long non-use (if it is true what the seller told me, the car has not been moved for about 8 years). But I am not sure if this issue has existed from the beginning of my ownership, it definitely got evident after I had the issues with water in the fuel tank. Could it be that some injectors got damaged by the water? My specialist recommended to use injection system cleaner (as additive for the fuel), but that did not help. Any ideas or hints?
Thanks and best regards,
Oliver