My wife took the Jaguar out Sunday and got about 15 miles away from the house when the check engine light came on and she started to "buck" on her while at a light. Got the poor engine performance message and she turned around and brought it home. I hooked my scanner and found code P0308, which is a miss fire detection on cylinder 8. I cleared the code, hoping it was a one time deal, and it ran great this morning. This afternoon on my way home from work, it acted up again, but no light. I washed the engine down Saturday, but had no problem with the car on the way home. I was wondering if anyone had any ideas before I replace coil packs. I don't have access to a scope, so I can't test the coil. I hope it's an easy fix!

 

Checking by substitution is the simplest way.

As the coil pack on Cylinder 8 is suspect, confirm this by switching it for another position and seeing if the relevant code then comes up for the new Cylinder number.

Graham

 

I'll bet you a that you have moisture in the spark plug wells.

 

Agreed, #8 plug is the one closest to the firewall on the left hand side of the car (while seated). My XK8 had issue with that and it was moisture in the spark plug well, the moisture gets in there easy, but doesn't like to come out.

 

Hmm While diagnosing a misfire condition in my 2001 Jag XK8 I found oil in the right rearmost spark plug well and also the two back wells on the left side. Also on the left side I found evidence of rust (reddish powder) on the camshaft cover beneath the coil packs - most in the rearmost well position but some in the well ahead of it. I replaced the camshaft cover gaskets per info gleaned from this website but the rust has been bothering me. Also the coils in those positions exhibit rust on their laminated (windings?).
a) Could this water intrusion have come from coolant recovery tank directly above (somehow(?) getting past the gasket on the coil pack cover)?
b) I did hose down the engine (house pressure hose) during a wash, is this a no-no?
c) If yes to any of these questions is there a fix (I was thinking about applying RTV sealant to the outboard edge of the coil pack covers (outside of the built-in gasket) before reinstall). This is the first time I have had the coil pack covers off on this car.
I should mention also my coolant recovery tank was dry but have yet to sort that out.
Any thoughts are welcome - also if I violated forum procedural rules by posting here let me now and I apologize as I am a new member.

edit: I noticed I neglected the vehicle mileage in my signature - it is 37K miles.