How often are they supposed to be replaced? My 117K mile XJR still had it's original spark plugs when they just got replaced. I don't think the spark plug wires have ever been replaced.

 

No spark plug wires. You have a wiring harness to each coil. There is a coil for every plug that directly connect to the plugs.

 

Spark plug wires?

Do you have an LS conversion?

The engine that is supposed to be in the car has individual coils that plug directly to the spark plug. No wires.

You MAY want to check the coil packs when you do a plug change.
Check for oil on the coil boots. If they are wet, you have a gasket issue.

Also, if true that the plugs have never been changed, be careful removing them.
Make sure the plug socket is seated properly on the plug and use even force when removing.

If you break or strip a plug, it's a bitch to fix.

 

The valve cover gasket was replaced.

 

You don't mention the year of your car, but for most X308 XJRs the original equipment (OE) plugs were NGK Platinum PFR6G-11E, which NGK subsequently updated to the PFR6G-13E (2341). Jaguar recommended changing them every 30,000 miles in supercharged engines (60,000 - 70,000 miles in normally-aspirated engines).

For the late X308s ('02 or '03) I think the specified plugs were changed from Platinums to Iridiums, and the recommended change interval was extended to 100,000 miles. However, when I changed the Iridiums in our '04 at 96K miles, the original plugs were obviously well past their prime and probably should have been changed at 80,000 miles or sooner.

By the way, just for clarity, our Jaguar engines are double-overhead cam designs (DOHC), so they have "cam covers" rather than "valve covers." But even the Jaguar parts catalogs sometimes refer to them as valve covers, so we can all be forgiven if we slip once in awhile.

Also, since the X308s have a coil-on-plug (COP) ignition system and every cylinder has its own coil, there are no "coil packs," which contain two or more ignition modules in one package and serve two or more cylinders. Instead, we have individual "On-Plug-Coils."

Sorry if I sound pedantic - I'm tired from getting my "new" 2003 X308 roadworthy so I can drive it while I repair our 2004 XJR which has a connecting rod problem.

Cheers,

Don

 

Spark plug wires on the X308 are on the same maintenance schedule as the muffler bearings and blinker fluid.

Check your manual to be sure. :-)

Plugs? NGK Iridiums, changed mine at 70K and they still looked good.
Vector