See my recent thread on this topic. Don't make my mistake. NGK 5464 are NOT the right plugs for a 2001 VDP. Several websites NOW online list them as the right plug. They are not. This has been confirmed by NGK and Advanced Auto Parts which also contacted NGK and reported back,

"Thank you for your recent email and I apologize for the inconvenience you have experienced with these spark plugs.

After checking your order and the part number you ordered, these do not show to fit your vehicle. According to NGK and their catalog, they did not start producing a spark plug for the Vanden Plas until 2003. The spark plugs that were purchased--5464--were listed for a 2003 Vanden Plas 4.0L non supercharged."


I bought them last year when they WERE shown to fit the 2001 VDP... and some sites STILL say they're the right ones.

My mechanic tested and the resistance is off the recommended specs for plugs for my car.

Hope this saves someone the hassle I endured. Now I must change out all the plugs.


SirJag

 

Hi SirJag
UPDATE - I received an email reply from NGK tecnical that confirms that the NGK 5464 is a suitable replacement plug for 2001 XJ8
Look at post# 21 in the thread: HELP! Mystery rough idle problem has us baffled!

I do not believe that Advance Auto Parts reply is correct. The NGK UK partsfinder shows 5464 as the upgrade plug for March 2000 to March 2003 for XJ model NA series.

We have been using NGK 3764 (BXR6EIX-11) the upgrade plug for XJR model for almost 1 year ago now and our engine is performing perfectly - No misfires or any engine DTCs.

I would be surprised if your issue is actually the 5464 plugs. I guess you need to replace them and see if the misfire goes away.

Also I received an this email reply from NGK last year:

"Subject: RE: NGK Form MailDate: Tue, 23 Aug 2011 08:56:17 -0400From: Hauenstein, Andrew <ahauenstein@ngksparkplugs.com>To: jimlombardi@***.net <jimlombardi@***.net>

Hello Jim,

The 1 step colder heat range won't hinder performance.

Best Regards,

Andrew Hauenstein
Technical & Training Specialist
NGK Spark Plugs (USA), Inc

-----Original Message-----
From: Jim Lombardi [mailto:jimlombardi@***.net]
Sent: Monday, August 22, 2011 8:58 PM
To: Info
Subject: Re: NGK Form Mail

Hi Andrew Hauenstein
Our 2001Jaguar XJ8 is Naturally Aspirated GAS Engine - It is not the supercharged version.

I noticed on the NGK UK website that the upgrade iridum spark plug for our engine is listed as BXR5EIX-11 (which is not even listed on the NGK USA website).

I also found the spark plug Part Number breakdown table in this PDF on NGK UK website. Looks like the NGK BXR6EIX-11 is almost the same spark plug as the BXR5EIX-11. Just 1 more higher in heating rating number (means it is just a little colder spark plug).

We changed the original factory spark plug (first time ever since car was put in service) 3 months ago at 100,000 miles. We had our mechanic put in the NGK BXR6EIX-11 and we have not noticed any difference in fuel consumption or performance.

Will the colder heat range plug present any future problems in our XJ8?
Please advise

Jim Lombardi"

Notice that NGK technical support did not mention that the 5464 plug is not the correct plug for our Jaguar.

Jim Lombardi

 

According to NGK's US website you will need the following:

Iridium IXBKR6EIX-11
These are the plugs reccomened by Jaguar as OEM
Use nothing but the best ;o))