'04 4.7 V8 spark plug choices

[KaseyMcc]

Hey everyone,
Sort of a noob question here, but I've been looking all over this site and the interwebs for answers and really haven't found any solid answers.

SO...

Looking at a spark plug change on my '04 V8 SR5 within the next couple weeks and I'm seeing lots of variation as to what sort of plugs to replace with. Between the NGK and the Denso, after much reading I've settled on Denso Iridium plugs; however, now I'm left torn between the Denso Iridium Long Life plugs and the Denso Iridium TT.
Most people seem to opt for the Long Life, but the TT also seems to have "advertised" advantages just like the LL, except for [apparently] a more efficient spark/detonation, as well as power and mileage gains (though I'm sure any 'gain' would be hardly noticeable, except in mileage).

My main question is regarding the gap--the Denso Iridium Long Life plug (SK20R11) lists a gap of 0.044" while the TT 4702 lists a gap of 0.040". Does anyone have any idea why the gaps would be different for these two plugs? Or could this just be as simple as "the TT comes pregapped to 0.040", you'll need to gap it to 0.044" "
Given my personality type I'm prone to over-analyzing and paranoia, but when it comes to engines with relatively small tolerances I think it's justified. It doesn't appear that my spark plugs have been changed in quite a while (I've only owned my 4R for 6 months/6,000 miles), but judging from the state of the coil pack bolts being heavily corroded I think the plugs could be as old as 100,000 miles if not more--it has 181,000 miles. I just want to replace them with good plugs, that won't mess with the ignition system, and (if possible) maybe bump up the performance or mileage a bit. Granted, if the plugs are really that old, I'll notice improvements regardless of the Long Life plugs or the TT, but I don't want to risk going with the wrong plug--especially considering the gap differences.

Thanks for reading! Any comments/answers are greatly appreciated!

 

[KYBubblehead]

I also have an '04 V8, so I await the same infoop2:

 

[KaseyMcc]

Done did it

[MENTION=133903]KYBubblehead[/MENTION],

I went ahead and guinea-pigged it yesterday. Yanked my plugs, they were the original Denso iridium long lifes...the name is well-suited as these plugs had just under 184,000 miles on them and were still functioning just fine--that said, I'm glad I replaced them. The coil pack bolts were pretty corroded so I replaced them as well.

I chose the Denso Iridium TT 4702. I was a bit concerned about the gap being .040" compared to the OEM spec of .044" but so far no issues, no codes thrown. I attribute the difference in gap to more efficient detonation, maybe hotter spark too? but that's just speculation on my part. I looked all over the web for answers, talked to parts guys at dealerships and even called Denso, but the call went to some engineer's* (*i assume) voicemail so I never got an answer.

Either way, I noticed immediate improvement in throttle response, acceleration, quicker starts, smoother idling and--in general--smoother running throughout the rev range. I'm pretty happy with the change.
While I was at it, I cleaned the coil packs with MAF sensor cleaner, and put a thin coat of white lithium grease on the inside lip of the connectors as well as where the coil pack boots meet the coil pack--sort of in hopes that it would help seal out water or dirt but was probably pretty unnecessary. I think the lithium grease on the connectors is a good idea though and won't be in vain.

I can't speak to the change I might have noticed if I had chosen the Denso Iridium Power rather than the Iridium TT, but I'm happy with my choice. So far I can't speak to any mileage gains, but I'm just going to bet it will improve that too--I just haven't driven it enough yet to notice (only ten miles on the plugs as of now)--but I will update this thread before long to give an idea of any improvements.
I'm also running a K&N drop-in, HCF delete and have my tires inflated to about 40lbs in hopes of milking every bit of MPG that I can.

 

[Jackkill1]

A spark plug change is on my list, mileage around 182k. Like you, my coil pack bolts are corroded. Did yours come out easily? Replacing sounds like a good measure. Did you get than from the dealer? Thanks.

 

[Pilotamis]

How easy did the plugs come out? I just picked up a V6 with 114K on it. The previous maintenance schedule leads me to believe these have been in there a very long time.

 

[ac13888]

I just went with factory plugs on my V8, just be careful not to drop the rubber seal under the coil. It took me forever to locate the one I dropped and made an easy job took forever to complete....

 

[oesterj1195]

How easy did the plugs come out? I just picked up a V6 with 114K on it. The previous maintenance schedule leads me to believe these have been in there a very long time.

I had 180k on my 05 V6 when I bought it and it had the original plugs on it. Denso on one side NGK on the other. I noticed almost no difference in performance after changing to NGK iridium. So I wouldn't sweat it unless you are having performance issues. They also came out pretty easily, surprisingly.

 

[KaseyMcc]

A spark plug change is on my list, mileage around 182k. Like you, my coil pack bolts are corroded. Did yours come out easily? Replacing sounds like a good measure. Did you get than from the dealer? Thanks.

How easy did the plugs come out? I just picked up a V6 with 114K on it. The previous maintenance schedule leads me to believe these have been in there a very long time.

I was worried about the coil pack bolts breaking because they were so corroded but they came out without any problems--I was pretty surprised. I replaced them with stainless steel flange bolts from a local hardware store I can't remember exactly what size/pitch they were but I can look.
The plugs themselves came out pretty well too--nothing broke so that was a huge relief. They weren't terribly snug, but I was still nervous.

Everything went back together just fine, just make sure you don't over-torque your plugs or coil pack bolts when you're putting it all back together. I also didn't put any anti-seize or similar on the threads. If you opt to use any anti-seize you will need to use a lower torque setting, but I'm not sure how much less since I didn't use any. For some reason it seemed like other's that used anti-seize went with a 2-3 lbs. less but I can't quite remember. You might also refer to the spark plug box for a picture that shows the plug and either 1/8 or 1/4 turn past hitting the surface--I would assume that same "turn" spec would apply to whether it has anti-seize or not, but this is just my ASSUMPTION--don't proceed without confirming through your own research, there's plenty of more information regarding torque specs on this forum--just gotta find it. Good luck, it's really not hard--just a bit intimidating due to the fear of screwing something up on a good engine.

 

[amitchell24]

NGK are a great bang for your buck IMO. No issues yet, though I just changed them.