Most reputable tuning shops recommend changing plugs every 20-30K miles especially for boosted cars. I'm in that envelope now. It concerns me that Jag lowered their interval from 96K to 50K on more recent models without modifying the original 96K cars' interval.

Thoughts for boosted and stock plug intervals?

 

The original 2014MY "maintenance check sheet" (ie service schedule) shows a spark plug change interval of 6 years / 96k miles for all F-Types except the V6S where it shows 3 years / 48k miles.
When I did the 3 year service on my V6S a bit over a year ago now I looked into this and nowhere could I find an explanation as to why the V6S interval was half the rest, and I can only guess it is because the V6S is slightly higher tuned than the others. Also, it seems later versions of the schedule no longer show the V6S as any different to the others.
Anyway, I had already bought a new set of plugs but I decided not to fit them because a) it's a pig of a job with very little room to move and special tools needed to remove the coils and the spark plugs and the rubber covers are apparently a right royal PITA to put back properly and I couldn't even get the SC coolant hoses off, and b) it would have cost a packet to get a workshop to do it.
Another year later and having run with extra boost for all of that year the car is still running beautifully with not the slightest hint that the spark plugs might need changing, so I'm not considering changing the plugs for at least another 2 years yet!

 

Rock Auto's listings indicate that the NGK 93476 iridium plug was the original part...has this been verified?

I've had iridium plugs last over 130K in non-boosted engines. They DON'T last as long in some of the older waste-spark ignition systems, though.

 

Yep, dems the ones. Also JLR part # C2Z28434.
They are actually NGK SILZKAR7E8S.
These are the numbers on the box and on the plug that I have in my hot little hand as I type.
I did a heap of research on replacement OEM spark plugs for the V6 and V6S before I bought these and I can can confirm 100% they are the correct plug.

 

 

I've seen tuning sites suggesting 20k intervals with iridium plags, and 50k for coils. But most are turbo charged, so maybe oil fouling is their issue.

 

Consistency is a virtue.

 

But stupidity is not, so we need to understand our own plugs under more boost. Inadequate or deteriorated plugs/coils are a good way to dentonate your engine fast. Good tuners like Roush, Burger, Hennesy, Lingenfelter, Ruf recommend frequent iridium changes as often as 10K. It is smart to understand our car, especial since Jag made them so easy to change. Not.
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Speaking of that, what's the book labor time for a plug change? Does anyone have a photo of the ratchet w/extensions needed?

 

Jimbo, according to my copy of the V6S Workshop Manual you need special tool JLP-303-1450 to remove the spark plugs.
Pretty much a certainty that the same tool would be recommended for the V8.
That said it is odds on that any reasonably short spark pug socket of the right head size would do the trick and you don't really need the special tool.
I'm sure there are some threads/posts somewhere over on the XF forum showing where a forum member MacGyvered a spark plug removal tool.
Also, I was sure I remembered seeing somewhere another special tool for removing the ignition coils but there is no such thing shown in the Workshop Manual, just an ordinary Torx bolt holding each one on.

 

Uhg. Boosting this car could get pricey if we need plugs at the top of their game.

Double-uhg, if you have to take the to the dealer to keep plugs fresh, let's hope they aren't nosey or bye bye warranty. My dealer is crazy aggressive, they told me aftermarket wheels voids my JLR warranty. They obviously don't know the law, but what a pain to deal with an uninformed dealer network thats become allergic to performance cars over the last 40 years.

We need a good DYI plug change video.

 

Jimbo, this is the best I can find so far: https://www.jaguarforums.com/forum/x...6/#post1252461
And this thread: https://www.jaguarforums.com/forum/x...XFR+spark+plug
Doable but a real PITA.

 

That'll teach me to do a pulley before verifying the plug change procedure. In my defense, I evolved from the swamp of rationale engine layouts.

Thanks.

 

Jimbo, I don't think you need to worry too much about regularly changing the spark plugs on a pulleyed and tuned F-Type.
As I said earlier I am still running the original OEM plugs which are now over four years old and nearly 50,000 km, with the last year of that pulleyed and tuned, with absolutely no hint that the plugs might need changing.
And that's with a 3.0 pushing out 450 bhp so 150 bhp per litre, which is equivalent to a 5.0 pushing out 750 bhp.

 

 

​​​​​​Because of the additional boost, the V6 S plug change interval is shorter than the V6 base, it is reduced to no longer than every 2 years. V8's are required to do a change every 3 years.

I think its wise to shorten that if running more boost than stock. I know its a PITA but thats part of tuning safely. Without any real data beyond Jag's own requirements, I recommend 2 years or 20K until we see some highly boosted plug gaps.

Another good idea is to have someone follow you and look for any unburned fuel or dark gray smoke exiting the exhaust tips as you approach redline. If any, change the plugs.

The reason I asked this Q isbecause I might have caught a glimpse of unburned fuel exiting mine during shifts, but its near impossible to see from inside the car.

 

For other people reading this thread, don't fall for JIMLIGHTA trolling. Spark plug replacement on F-type according to maintenance schedule is every 6 years of 96,000 miles.

 

pulled mine at about 30k+- to swap for a colder set and they looked brand new. this isn't that difficult of a job, It's honestly not any more difficult that an other later model engine, 80% of the work is shields and coil packs. Only drawback is the $$ of the plugs.

 

Thats great news would you mind posting your lessons learned or a diy? What were the gaps?

 

Did you need any "special tools" or need to modify any of your existing tools, such as grinding excess length from a sparkplug socket, or using any 'special' procedures??

 

Can someone please explain the rationale behind the age limits on sparkplugs? Age and mileage MAY have a rough correlation, but AFAIK plugs are a wear part that only wears with use, unlike fluids that are rightly time limited.