Here's some reading that you might be interested in

https://www.jaguarforums.com/forum/x...0-coils-93966/

Cheers
DD

 

So, a bad thing?

 

The corona staining is no big deal; no harm comes from it.

Oil in the spark plug wells is not a good thing

Cheers
DD

 

Thank you. The plugs I removed had such staining and a ring of some white powdery stuff at the base of the coil boot.

 

I hereby proclaim that the RC12YC that I am using is better than the RC12YCC!!

Just kidding, Lol. Don't get excited anyone.

Actually, my spark plugs are missing a C on the end of their name. What does that mean? Should I be worried?

 

R = Resistor
C = 14mm x 5/8", 3/4" reach, no taper seat
12 = heat range
Y = Standard projected core nose

C = Copper plus design
... or ...
CC = Double copper

 

Dear Friends, I need to have my Spark wire cables reworked and I need to know the length of each one of the 12 cables. My jaguar has 2 ignition coils. can some one help me ?

 

Hello Sidney,

There are replacement kits available that include all 12 wires to fit the two coils of the 1995 XJ12. I got a Bosch kit a few years ago.

This issue is irrelevant to the discussion above, as the V12 is a very different beast than the AJ16 engine of the XJ6. It also uses different spark plugs.

We have our own section for the X305 XJ12. Feel free to post there, its right above the X300 section on the main list.

 

Thank you all for all the information to make this a good adventure in Jaguar owning.


So I thought I would share something that is probably embarrassing but I could see it go un-noticed.
Short Story: Cyl 6 and Cyl 5 coil wires are really easy to mixup.


1995 Jaguar XJS 4.0 6 cylinder AJ16
24K miles.
Was changing spark plugs, because fuel consumption was sub par / could feel it wasnt purring exactly right.
NKG copper -- tried .025 and .03x gaps -- rough idle, returned them.
The Champions I had in there were actually not bad, but they were gapped by last owner at.035.

Put the original champions in -- rough idle.
Changed them to .025 gap, and cleaned everything.
-- rough idle.

Stood there and realized that #5 wire and #6 wire to coils are same length, and #5 (so it turns out) actually came out of the harness behind the #6 wire.

So that's it. not only was this solved by switching #5 and #6 wires, but at .025 gap... .. well its just right, and gunning it, it was a whole new beast.


GL,
David