Hi guys, I have recently had my XK8 back from having a reconditioned gearbox fitted, it came back with the added attraction of having a PO354 fault code. I changed the coil pack on the o/s rear and also as Gus suggested the plug also. However when I changed the plug it was with one of the originals fitted to the car, which was NGK IFR5N-10 7866.
Here is where I get confused, last year when I changed the 2ndry tensioners I fitted new NGK Platinum plugs PFR5G-13E 2761.
Now when I check the NGK website they recommend Platinum BKR5E1X-11 5464!
NGK Spark Plugs

So have the OE Platinum plugs 7866 ( at least OE to my knowledge ) been superseded by the 5464 version?

Anyone with any info to clear this up?

Many thanks for any help offered.

Arty

 

I believe that it is the iridium plug, which I understand to the current recommended plug. Also, it is less expensive than the OE platinum.

 

Well I got to the bottom of it, rang NGK UK 01442281000 and asked what were the correct iridium plugs for my year and model. The answer was there are no iridium plugs available for your car!
O.K so problem solved and who ever had the car before me put the wrong plugs in. I apparently have the correct Platinum ones fitted apart from the rear o/s one.
Just posting so others do not have the run around I have had.

 

Here is the NGK chart, as you can see it varies by engine/year

 

Thanks for the chart Stumpy, I was looking at the U.S chart apparently. Looking at your chart the difference in year/months of production are quite small from 09/98 to 03/00 and 03/00 to 02/02 for the AJ27 motor. The 2761 is a platinum plug and the 3000 is Iridium, its the same motor and most likely the same injectors, control modules etc unless someone can state otherwise? So what changed to allow the newer motor to take the Iridium plug, anyone know?

 

The development from Platinum - Laser - Laser Iridium was claimed by NKG to be for longer service life.

The recommended plugs are to match Jaguar's specification and the variable here has to be heat range.



The balance is between the tip being hot enough to 'self clean' but cool enough to avoid 'pinking' (pre-ignition).

Presumably the precise engine mapping over the years was matched to available plug technology at the time .......

Graham

 

Yes Graham, when I spoke the the person at the technical dept she said it was all to do with heat distribution.
There must have been some other developments from Jaguar between my car and the next update to resolve those issues, as you say may have been in the ECU or firmware as its the same AJ27 engine everywhere else.