I am disgusted with spark plugs at this point.

Just put in new TR6IX's because running the cold TR8IX's did not change my truck's tendency to get light pinging at 17 degrees WOT, as well as my truck dropping 1.5 MPH at the track recently. Anyway, with the new TR6IX's in, I get an occasional single missfire at idle here and there. It's like it missfires only once in a while, otherwise it idles smooth.

I also gapped the new plugs at .032, whereas the old ones were gapped at .035

I am thinking about changing plugs again, and I prefer the best smooth idling plugs, because even an occasional miss once in a while makes me feel like the truck is a POS.

I went with iridiums because they are supposed to have smooth idle, and be easier for the coil packs to fire, compared to conventional design plugs.

I am approaching 15k miles on the truck.

1. Are the coil packs not what they used to be? No aftermarket? MSD?
2. Are iridium plugs supposedly the smoothest idling?
3. Any reason to believe that NGK iridiums aren't as good as the Denso's?
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Denso's
NO AND'S IF'S OR BUT'S!!

Although most L's will run extremely good on NGK's, SOME WON'T.
My L absolutely hates them, noticed the schitty idle the second they went in, cooked a set of TR-6's in 500 miles. Put Denso's in for 3 years and immediately noticed a perfect idle and fell in love with them. 3 years of flawless street and strip on the same set.

Used NGK BR7's in the new motor, immediately noticed the schitty idle and cooked them at 500 miles. Put them in again (DON'T ASK ME WHY *$%@#$)
and immediately noticed a schitty idle.

Denso IT 22's ARE going back in....

They are known for NO misfires at high RPM
and EXCELLENT Idle. They simply are the Best!!

 

I've had my denso it-22's in for about 18 months now, and I love em. I think they may be a range to cold for my mods (4#, Apten, LT's). I may try some IT-20's soon, if I don't get the nitrous put on.

 

Blown347,
I'm using the TR7IX plugs @ gapped at .036 with a 6# lower and very similar mods...Stock Coil Packs & I'm in very similar weather as you... w/ several Tampa-Boca-Tampa trips over the last four months in a daily driver.
They've been in since 04' Thanksgiving weekend, no idle problems or misses at WOT.
Art

 

Thanks for the input guys.

Up top, there is no missing, and the missing at idle is very sparce, not consistent at all. It's almost as if once in a while just one spark doesn't fire, and then it's fine again, all in the same instant. Kinda hard to explain.

I guess I was just thinking that the idle should be Cadillac smooth, and maybe that's not going to happen?

 

I just(tonight) pulled some TR6's out of my built long block and put a set of IT22's in it and damn what a difference in idle quality. Yes it has cams, but with the TR6's it was beating and rattling around pretty good. Now it has smoothed out a lot!

 

Hey Rob,
The Densos work great for me too. I would like to narrow the gap a little but I'm worried I will damage them. How the hell do you correctly gap these things?

TB

 

Use the gap tool to carefully bend the ground strap. I use a feeler gauge (not the wire type) and don't use really any pressure to force the feeler gauge into the gap.

 

Well it happen again.
Last night I went to Dyno, Sal strapped it down, made a pull, shook his head, shut the truck off and started getting out tools ???

I said WHASSUP SAL

He Said you got a bad plug, and sure enough yes I did "AGAIN"
So there's the 3rd set of NGK's to only getting 500 miles out of them.
(actually we got 600 out of this set)

AND YES he put DENSO IT-22's in, immediately all my idle probs and low RPM misses are gone, (lets see if I can get 3 yrs out of these) WOO HOO............

Dam NGK's *@$(@$@($^%@($%(@$^%(@$

Track Beast, this is the type of feeler guage you need
You use those thing-a-ma-jigs at 3:00 and 9:00 on the Denso Tips "to open and close them"

 

I wonder if Denso iridiums are different (better?) than NGK iridiums?

 

when I install a fresh set of NGK TR6's the idle is great but after about 2 weeks, no better or worse than stock.

I went with the Denso IT's and at first start up they were as smooth as the TR6's but after 2 weeks, the truck idles like a cadillac. That was almost 8 months ago and it idles better every day. I absolutely recommend these plugs and they are well worth the price if you want to leave them in and forget about 'em.

Just anf FYI, the truck will idle even better with the stock lower pulley on. I put it on to do some testing and was wondering if it was even on. Guess all that rubber makes a difference.

 

It's starting to look like I need to try Denso's on my next wonderful spark plug change.

 

For what it's worth NGK iridiums are just as good as Denso's in my L plus they are less expensive..

 

When I contacted NGK Corp. a year ago when I was selecting new plugs, they told me that they did not offer a plug recommended for my application. Maybe they have one now, I don't know.

I went with the Densos and no regrets.

TB