Piece of cake; no, really. My 2006 just hit 95,000 and although the
motor runs like a clock, I figured it was time for a plug change. So,
deciding to stay with the original NGK IR plugs, I gave the guys at
Nalley a call and ordered a set. After they arrived, I stared at them
for a month or so, thinking the job was going to be a real pain. It
turned out to be one of the easiest plug changes I've done. I've
attached a few photos. What amazed me was the condition of the
originals which you'll see compared to the new. Jag specifies a gap
of .035 to .039; the old plugs gapped at .036...hardly any wear at
all.

You'll need a 5/8th spark socket with a six inch extension on the
wrench. Also a tube of anti-seize; I purchased a small tube of
Permatex 133A which probably has enough for every car on the
forum. Don't even think of installing the plugs without anti-seize.
Also (optional) two shots of Jack Daniels...actually three...I'll talk
about that later.

Here's the drill. Remove the engine cover with a small phillips; you'll
only need to turn the screws about a quarter turn. Remove the oil
filler cap, lift off the engine cover and re-install the filler cap. Next,
on the driver's side, put the fingers of both hands under the top of
the plug/coil cover and pull back quickly. Slide the cover (lots of
fun as the fuel line is in the way) forward and remove. On the
passenger side, place your fingers under the BOTTOM of the cover
and pull back. On each side the cover is held by two 'tabs' that
fit over stationary screws.

Now your will need a very small screw driver to slip under the
the top of the clip that holds the wire loom to the coil. So, remove
the bolt holding the coil, lift the coil up slightly, and, using the
small screw driver, pry the connector off the coil. The coil lifts
out easily. I did one plug at a time. Remove the plug; you'll see
why you want a dedicated plug socket; those plugs are deep down
and the rubber inside of the socket firmly grips the plug. Place a
small..emphasis on small..dab of anti-seize on the plug threads starting
about three threads up from the bottom of the plug; with your finger,
wipe the excess anti-seize off the plug threads and lower the plug
down into the well using the socket and the 6 inch extension. Don't
attach the wrench yet. GENTLY turn the plug into the hole; it should
turn easily. If you meet ANY resistance, back the plug out and try
again. I experienced no problems with this; if your extension is
straight, the plugs will thread easily. Turn the extension by hand until
the plug snugs down, then attach the wrench to the extension and
tighten the plug until it's snug. You now have two options; tighten the
plug 1/8th to 1/4 turn, or, attach a small torque wrench to the extension
and tighten to 18 ft/lbs. Either way will achieve the same result.
Lower the coil over the plug and snap the connector on before you
thread the bolt holding the coil; if your hands are big like mine, it's
easier. Pour the first Jack and Coke and proceed with the other
three plugs.

Move over to the passenger side, pour another Jack and Coke and
remove the small disk (I think it's an emission device of some sort)
by removing the two torx screws and folding the device out of the
way. I started with the front plug and proceeded back to the firewall.
The last plug closest to the firewall on the passenger side elicited
more than a few swear words and that third Jack and Coke. The
toughest part was getting the little screw driver under the clip to
remove the coil connector...not that hard, really but my hands are
too big. Oh yeah...you might want to remove the bracket that holds
that really big wire loom over the plug area by removing the two bolts
on the fender. Once I was able to get the loom out of the way, the
rest was easy.

When done installing the plugs, install the covers; you'll easily see
how they fit over the two screws. Push down on the cover, and all
is well. Install the engine cover. You're done. It took me about an
hour and 15 minutes.

HERE'S THE BEST PART. Out of curiosity, I called the Jag dealer in
Seattle and requested a quote to change the plugs...parts and labor.
You might want to sit down before reading further. Ready? Eight-
hundred bucks! No, that's not a typo.. $800 dollars! With tax that
would bring the total to around $863 dollars. My cost, including plugs,
tube of anti-seize, socket, and Jack Daniels and Coke? $105.20.
I know what you're thinking; I didn't get a free cup of coffee and
donut and get to look at the attractive receptionist at the dealer
who pronounces Jaguar as 'Jagyouare'.

If the photos don't transfer, e-mail me and I'll forward them.

 

The is the comparison of old plugs vs new.

 

I thought I had a photo of old vs new. These are the old. The center
electrodes look exactly the same as the new. I think I'm sold on
Iridium plugs. You'll also notice that Jag uses an anti-seize compound
on the plugs. I can't emphasize the anti-seize compound enough. You
never, in this life, or any future life, want to deal with a plug that is
seized in an aluminum head. More often than not, if you are able to
remove the plug, the threads will be destroyed and even a heli-coil
won't save the head.

 

Good job, what is surprising is that spark plugs run fine but if you judge them by solely looking at the pics you sent , you could say : Gosh those were junk lol

 

Great job. Denso and NGK iridium plugs are indeed fantastic. Changed a set of Denso iridiums in my wife's previous 2000 Lexus RX300 AWD at just over 120,000 miles. They still looked and performed perfectly. If I had not been preparing the vehicle for sale, I would have slipped the old plugs right back in place and returned the new plugs to get my money back....

 

iridium plugs come pre gapped...Never gap a iridium plugs. It destroys the tips... Hope you didn't throw a 100 bucks away.

 

HERE'S A BIG QUESTION:
Why buy spark plugs from a dealer? The auto parts stores carry the same NGK plugs for a lot less.

GOOD JOB ON THE THREAD AND POST.

 

You can still gap iridiums it just has to be done properly. They should always be checked. My video from my youtube channel in my sig has a spark plug video and I go over the proper way to gap an iridium. Actually should gap all plug that way.

 

Yes they come pre-gapped to a specified dimension. However, it is entirely safe to gap them within a small range as long as the center electrode is not abused.

What should not be done is to buy a plug with a .060" spec and hope to get it down to say 0.28" gap. That results in a sloped ground electrode. Same thing with a .030" spec plug and trying for a .060" gap.

 

The 2nd and 3rd pictures are a good opportunity to see the effects of erosion.

Both the center and ground electrodes exhibit rounding of the original sharp edges.

Sharp edges promote better firing at low rpm. One of the reasons that the long life plugs use a fine center electrode is to combat the effects of this erosion. As can be seen, it is sucessful to some degree, but it is still there.

 

Thanks for the info! I wasn't even thinking that if you gapped them like shown in the article below it would work..
How to properly OPEN the gap on NGK IRIDIUM plugs - SRT Forums - SRT4, SRT6, SRT8, SRT10 & Dodge Forum