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Spark plugs for LNF

14K views 24 replies 11 participants last post by  JohnWR 
#1 ·
Has anyone tried a bosch or E3 spark plug in their GXP or Redline? I used the bosch "plus 4" plug in my 2.4 NA and it worked very well. I like the idea of unshrouding the spark. I was not sure if that design would be successful in an LNF engine, where chamber cooling plays such an important roll.
 
#3 · (Edited)
anyone have the part number for the ngk 1 step cooler plugs for the 2.0l turbo? As cheap as plugs are i was thinking of changing mine as they have 70,000 miles on em.

EDIT: I just found them on amazon for $12.14 each with free shipping. It is the NGK (3787) ILTR6A-8G Laser Iridium, though on there it says this does not fit our cars. anyone know if that is the correct part (i found part # on this forum)
 
#4 ·
Get the IX line over the Laser Iridium line. Apparently, the IX line is the premium, and the Laser Iridium merely OE replacement. I'd suggest the LTR6IX-11 as the recommended 1 step colder plug. I don't seem to be having any over heat issues on the stock LTR5IX-11, probably because I run rich under boost (~.89) for safety, but still stoichiometric (1.00) under cruising, so it still gets the opportunity to self-clean as it hits its intended temperature operating range.
 
#6 · (Edited)
Both have iridium tips, but the one you are quoting has a small piece of platinum pressed into the ground electrode, which in theory should last longer, which is why it is guaranteed to last at least 5 years or 100,000km. The one I'm quoting does not have the platinum insert in the ground electrode. However, due to the large size of the ground electrode relative to the tiny tip of the iridium side, it's not the ground electrode that typically wears and as a result does not cause the gap distance to increase, which is harder on the coil packs and causes ignition problems. Instead, it's typically the iridium tip that ends up being the issue, not the ground electrode. So either should give you 5 years and 100,000km.

And btw, platinum in spark plugs tends to be for durability, not performance. For example, many cars run better on copper plugs than platinum plugs. It's just that the superior service life of the platinum outweighs the better performance of the copper. So theoretically, the non-platinum tipped one has the performance advantage edge, while the platinum tipped one has the longer service life edge.
 
#7 ·
I guess i will go with the cheaper part you recomended because realistically i dont see myself leaving them in past 30,000 without a change anyway.

One last question has anyone tried denso or any of the other brand irridium plugs with better results or is NGK the way to go?
 
#9 ·
30,000 interval is rather short and over kill, but hey, if that's what you want, go for it. However, either of the NGK plugs we're discussing should easily make it to 80,000-100,000km.

Denso's plugs are decent as well, no complaints there. Just stay away from the E3, and even the Bosch +4. I've seen lots of overheat issues with the E3, and the +4 tends to block off the spark, and accompanying flame kernel so much, it can actually impede performance depending on the application.
 
#13 ·
I would have a good dealer look at it before buying new plugs.
With 28K it should not be missing, it could be something else.
 
#15 ·
I only notice the miss at idle, otherwise it runs great. I will check the plugs and see what I find. There's nothing weird about pulling the plugs on these motors is there? I haven't even seen them yet.
 
#17 ·
I pulled my plugs they appear to be in decent shape. They are the ACDelco 41-108 plugs. My intake tube does have oil in it past the PCV insertion point though.


Vacumn lines are in great shape, no cracks or rubbed through spots. I guess I will try re-seating them or spraying some cleaner around the intake manifold to check for a leak.
 
#18 ·
I found one possible vacumn leak, plastic nipple for the power brakes was loose. The car still idles crappy though. It will idle perfectly for about 20-30 seconds after you come to a stop then it will start popping and shaking. It's a pretty steady miss, you could almost dance to it. I am looking for loose grounds now, only one I have found so far was tight but I loosened it and moved it around. Should I replace the plugs anyway? I was searching and saw several posts where people needed there plugs changed with under 10k miles.
 
#21 ·
I reset all the grounds, and threw in a can of seafoam with a few gallons of gas on top. So far it seems to be running better. I would no longer classify it as a miss, now it's a very light rough idle. I doubt my wife will even notice it now...I usually know something is really wrong if my wife notices it. I will keep my eye on it though to make sure it holds up and told my wife not to get cheap gas anymore, just in case.
 
#23 ·
I have been getting the 91 octane from either Chevron or Texaco. My wife is used to filling up at the maverik station near her work. While I dont believe it's the worst gas in town, it's not the best. I would imagine the injectors on these cars are a bit more sensitive to contaminants being in such a harsh environment. I have instructed her to only use Chevron and Texaco as well. I will also be tossing in some cleaner every couple weeks as well.
 
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