Thanks to the many easy to follow instructions in this forums and a helpful YouTube video I changed the spark plugs and upper intake gaskets in 40 minutes. It was extremely easy thanks to all the instructions. Not as easy as my straight 6 XJS, which an elderly blind person could probably do in 10 minutes while simultaneously watching wheel of fortune, but nevertheless very doable for anyone with the appropriate tools.

I was hoping that this will improve my tragic MPG. I have ordered a new PCV valve since the manifold was full of oil. Cleaned the MAF throttle body again.

I am not getting too excited about MPG though, because the spark plugs that came out where in pretty good shape:





I think those are Motorcraft platinums based on the number, so I don't think they are original.

 

Good job..This can be a daunting task for some..glad you showed it is very doable.

 

Spike, humor me and what I want you to do is to block the front wheels and then lift the rear wheels in the air. Ensure the e-brake is not set. Now, find the e-brake lever to the caliper and move it as far as you can towards the back bumper. You should be able to rock the rotor back and forth fairly easy. Worst case, remove the caliper, push the piston back a slight amount 1/32" to 1/16" and then reinstall. Repeat on the other side. Now, without ever setting the e-brake during the next tank full, see how your mileage is now. If you see a marked improvement, what you are experiencing is what I am. The e-brakes don't quite release all the way and the lightly drag on the car, causing it to have more rolling resistance. if this is the case, let me know and I will give you a few things to try.

 

Absolutely doable. I remember when I was about 12 in 1995 and my grandfather bought the XJS I now own, he said, "this car is not for the home mechanic. It will have to be serviced at the dealer only!"... 17 years later I do most of the maintenance on that car. On the X type I am finding that a lot of the things I have heard are incorrect. Anyone who has changed spark plugs, has a metric socket set, an hour or two and can follow the instructions in this forum is capable of changing the spark plugs.

Now if changing the rear driveshaft is as easy as this......

 

Thanks for the details instructions, greatly appreciated. I will try this and post back

 

How interesting.

The plugs that came out of my car are exactly the plugs this member removed in this post:

https://www.jaguarforums.com/forum/x...k-plugs-85327/

Identical markings, so I guess mine where original. Based on those number these are Motorcraft SP-459