I changed my spark plugs yesterday, I remember back in the day when it was pretty straightforward, but I actually had to pull out the JTIS to figure it out on the Jag. It's really simple once you know how to get to the plugs. Here's a video I made just in case anyone else needed help. It took me about 2 hours, but that's because I was messing with the camera. Without trying to make a video I probably could have done all 8 spark plugs in an hour or so.

Here's the VIDEO.

 

I suppose I should FAQ this vid sam, you're on one of your documentary streaks, aren't ya?

 

I figure if I scratch my head while attempting to do something, other people probably do, too. Hopefully this will make it a tad easier for someone else.

 

You can turn your hand at anything , kudos to you

 

Sam,

You're amassing quite a collection of video repair procedures - good for you and good work! Maybe consider starting a Jag repair site! Lots of members comment your videos have been a large help to them.

I used your visor repair (credit to you). I had a customer with a broken clip, but in his case, the plastic was also cracked so I had to improvise, but nonetheless, yours provided the foundation for the fix.

Best,

 

Thanks for the kind words, Steve. Jaguarforums is the only Jaguar repair site I need, however. No site I could create would have the expert help of hundreds of Jag experts like JF.

 

Sam...what plugs did you install? Thanks...
Craig

 

I find these videos to be invaluable! You are providing a great service to the jaguar community Sam, keep up the good work.

 

I did about two days or research before buying plugs. I was going to buy some super-expensive iridium "pulse plugs", but the more I read about spark plugs the more I learned that the expensive, gimmicky plugs are in many cases inferior to regular old copper or platinum plugs. I ended up buying Bosch Platinums for $2.99 each. I didn't even buy the Bosch Platinum +2's or +4's because they apparently reduce the gas mileage! Go figure! The plugs I removed were Champion Platinums and they looked nearly identical to the Boschs. I'm not sure what's installed from the factory, and I don't know when the ones in my car were last replaced, but the ones I pulled out actually looked pretty good. They probably didn't need replaced.

However, every one of the old plugs was gapped at .030. Jaguar specs call for them to be gapped at .044.

 

Jaguar has been using the iridium plugs since the 4.2 V8 engines. I have them in my 04 XJ8 and put them in my 01 XJR. Average mileage went from 18 mpg to 20+ mpg.

 

I found several references to a Consumer Reports review of spark plugs, although I didn't find the actual article itself. What I found said that Consumer Reports didn't find any statistical difference between spark plugs when it came to gas mileage or horsepower, and some of the high-dollar plugs with weird shaped tips actually got slightly worse gas mileage (but not statistically significant.

The article also said that the main difference between copper, platinum, and iridium plugs was the longevity of the plug. Platinum has a higher melting point than copper, and iridium has a higher melting point that platinum. The higher melting points mean the the tip of the plug erodes more slowly and the plug lasts longer. But as far as performance, a plug's a plug.

 

Correct gus, iridiums are OEM and were in mine when i bought it.

 

Oh yeah... something else I read about spark plugs; The different metals have differing abilities to carry away heat. A hot spark plug is more likely to cause pre-ignition (engine knock). On turbo/supercharged engines that can be more of a problem because the extra pressure is more susceptible to pre-ignition. Copper is the best conductor of heat, therefore it's the least likely to cause pre-ignition from the "glow plug effect". It can more easily channel the heat away from the tip of the plug. Platinum and iridium are less effective at conducting the heat away, and more likely to cause pre-ignition.

Manufacturers like the iridium plugs because they allow them to brag about the 100,000 mile tuneup intervals. Most engines don't operate anywhere near the temperatures and pressures that would cause pre-ignition, so heat conduction of the spark plug isn't an issue.

 

Sam,

Actually, spark plugs are manufactured in different heat ranges within every "type" plug. They range from cold to hot. Engine builders/tuners are always testing spark plug temperature range to run best within the operating range needed. For example, and engine going into a 1/4 mile drag car will run a different spark plug temperature range than the same engine, unmodified in a street car. This is very simplified, but it is actually far more complex and quite a science. For production cars, for example, factory engineering picks a temperature range that best operates under all useage conditions.

An example of a factory mistake was the AJ16 six built for the X300 series (95 to 97). The factory specified two different heat ranges for the plugs in the NA vs. the SC. The SC used a colder range plug because under the hotter/higher cylinder pressures the colder plug was needed to prevent pre-ignition. On the NA, which used the hotter plug, some owners complained the engine was experiencing pre-ignition at WOT, so the factory issued a TSB changing the NA plug to the colder range SC which solved the problem at WOT. It did, however cause a little bit of a cold start issue, but less impact than the hotter/higher cylinder temps caused.
You can usually decipher the spark plug temp range by its number. For example, the plug ranges for the AJ16 in a Champion was:

RC12YCC - for the SC
RC9YCC - for the NA (then the factory changed it to a RC12YCC)

There is also an RC10YCC and an RC11YCC, all of which "fit" the AJ16, but will cause different engine performance effects based on plug temp range. All of these plugs are Copper/copper (the CC part in the number) but perform very differently.

I should add that aftermarket parts books and conversion charts have errors in them all the time. Whenever I read that someone has a start or run problem after a spark plug change the first thing I look at is what plug they put in. The parts book will specify the right plug in a crossover, but the wrong temp range.

 

Great job with the videos Sam. That is really very kind of you to take the time.
I really enjoyed the "head rest repair" video.