Spark plugs again.

[Hoges]

My 2000 XK8 handbook says plugs should be NGK PFRSG-11E. So I bought a set. As I am changing the tensioners and chains @62,00 miles I thought I'll change the plugs!

First plug out is a 13E!! This is a 1.3 mm gap as I understand it. Should I fit the 11E's as they are, or open up the gap? Or buy 13Es.

Did anything change on the engine to reduce the gap after March 2000 which seems to be when the 11E came in?

Hoping for an inexpensive awnser!!

Pete H.

[mike020150]

Jaguar lists 4 different part numbers for plugs used in the V8 (for unleaded fuel). They vary by model year and the gaps alter as well.

97/98 NCA3850DA 2 1.0 - 1.1MM
98/99 NCA3850FA 1 1.2 - 1.3MM
99 AJ8 4575(IRIDIUM) 0.9 - 1.0MM
99 XKR NCA3850HA 2 1.2 - 1.3MM
2000 onwards ALL MODELS
AJ8 4575(IRIDIUM) 0.9 - 1.0MM

Hence, when in doubt go for the iridium version (NGK number IFR5N10). The plug gaps are pre- set and shouldn't be altered. Mike.

[Hoges]

Thanks Mike.

Pete H.

[doug424]

Continuing the thread of confusion...

Hello everybody.

Recently changed the spark plugs on the car and followed the handbook and fitted NGK BKR5EVXA-13 plugs.

To my surprise I removed NGK BKR6EVXA-11 plugs.

My car was built 16/2/1998 (I think). According to the NGK website cars built September 1997 to September 1998 should use BKR5EVXA-13 and those before September 1997 BKR6EVXA-11.

A couple of questions come to mind;
1) Why I should find the earlier type of spark plug fitted?
2) Why did Jaguar change the specified type?
3) Will I notice any difference?

For the first four years, up to 68,359 Km (42,724 miles), it was maintained within the German Jaguar dealer network. Given the service interval for spark plugs is 30,000 miles (46,000 Km) it must (should) have had its build spark plugs changed whilst under the care of the approved dealer network. Current odometer reading is 114,000 Km (about 71,000 miles) so the change now is just about right.

For information, six of the eight had some oil on the thread; one plug offered little resistance to being removed and one virtually no resistance. All the plugs had red staining of the insulation near the electrode which I am lead to believe is due to additives in low quality unleaded petrol.

Doug Barrass,
Ashford, Kent.

[mike020150]

Hi Doug,
Jaguar changed both the plug type and the replacement interval over the production life of the car all of which contain the seeds of mounting confusion for anyone maintaining them. Emission regulations also changed during production so Jaguar refined the engine management system and fuelling in response. Additionally there were attempts to minimise the cold start flooding issue. A combination of these issues plus the introduction of the much more durable platinum range of plugs are likely to be why Jaguar changed its plug recommendations over time.

According to Jaguar, the deposits at the bases of the plug insulators are caused by ionisation of oil particles and are not detrimental to plug performance.

Unlike the AJ6/16 six cylinder, I haven't heard of these engines being especially sensitive to the different plug grades so it's unlikely you will notice any practical differences. Mike.