As soon as I got my new 1995 6-cylinder XJS coupe, I replaced the spark plugs and took pictures. I'm a novice mechanic, so I apologize for any mistakes or misinformation. Here's the procedure I followed:

1. Open the hood and find the coil cover with the Jaguar logo
2. Unscrew the three (3) Torx screws holding the coil cover in place. The Torx screws appeared to be larger than T40, the largest I have, so I'm guessing they're T45 or T50
3. Remove the coil cover
4. The coils are held in place by two (2) 8 mm hexagonal bolts each. Remove these. I removed all six coils before replacing any of the spark plugs. The ignition wires must be unclipped from their clips before removal
5. Pull out the coils. They should just unsnap from the spark plugs
6. Using a spark plug socket with a socket wrench and extender, unscrew and remove each spark plug in turn
7. Smear a thin coating of anti-seize compound on the threads of each new spark plug before installing and torquing down with a torque wrench to 21 lb-ft. I used Bosch Platinum spark plugs.
8. Before replacing the coils, smear some dielectric grease in the hole which the spark plug plugs into
9. Be sure to replace the coils in the proper order
10. Before re-bolting the 8 mm hexagonal bolts holding each coil in place, make sure that the coil is securely plugged into the spark plug (you should feel and hear a click). Smear the threads of the bolts with anti-seize compound
11. Re-bolt the 8 mm hexagonal bolts holding each coil in place
12. Replace the coil cover
13. Smear the Torx screws with anti-seize compound and screw them back in place
14. Close the hood

Please let me know if I did anything wrong!

 

Good work !

Did you make sure the plugs were properly gapped before installing?

Cheers
DD

 

Thanks, Doug! The spark plugs were pre-gapped and non-adjustable, so I left them be.

 

You XJS should have Champion copper core resistor plugs. The ignition systemwas not designed for Bosch Platinum plugs. My 95 was giving me misfire codes with Bosh Iridium’s.So, after talking with Hennessy Jaguar they convinced me to go back tothe champions, which I did and no more misfire codes. Check in your manuals forthe correct plug.

 

Thanks! If I have any problems, I'll try that.