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Old 07-16-2005, 02:59 AM   #1
caterpill
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Cool Checked ONE spark plug, saw some signs of detonation ... damn. So what now?

I've recently had a spark plug change on my mind for a while now, except I didn't know whether to wait until ~50,000+ miles, or change it now while i'm at 41,900 miles.

Anyhow, I got bored today and I decided to take a plug out, and choose the easiest to access, the passenger side front, I don't recall the exact cylinder number.

What I saw when I took it out, bewildered me..



The pictures depict plugs that are somewhat normal, and to be honest, it looks different in person. The deposits look more white. I tried to take a pic without flash but there was hardly any light.

Well, I have a 7 megapixel cam and when I zoom up, I do see what I wish I hadn't... but it sure looks like balls of metal. I guess i've been detonating, but how would I tell when it happened? These stock platinum plugs have been in there since 40,000 miles ago, so would there be a difference between detonating at 10,000 miles and 39,000 miles?



Anyhow. Recently, i've been having some trouble with the "04 WRX Detonation" apparently due to severe jerking from CL/OL fueling switchover. A few times in the freeway where I had to do WOT then switch to half throttle, etc, caused this severe jerking and of course probably detonation occured.

My concerns, are that if those metal deposits are from my pistons, how much have I damaged anything? Is this something someone would call severe, or moderate detonation?

I was planning to get some regular but WRX-specific NGK Copper plugs, but I wasn't sure yet if I wanted to commit to a 12k interval. Looking at the plug above, they seem alright in terms of electrode wear, but should they be swapped out already? Oh, and not to forget, my car is mildly modified. I have a Catless 3" turboback, and a catless uppipe. I currently use a regular oem style paper filter. My driving habits are about 40% hard and 60% regular off-boost driving, so I definately think colder plugs are out of the question, no? Lastly, would a copper plug last to 15,000 with my driving habits? Or, would 15k intervals be pushing it, causing too much stress to my ignition sytem?

I know it is a lot to ponder just from looking at ONE plug, but i'm just concerned.

Any help would be greatly appreciated.

Thanks.
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Old 07-16-2005, 09:24 AM   #2
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What kind of fuel do you run?
Use ANY fuel additives?

http://www.boschusa.com/images/SparkPlugFaces.pdf

It looks pretty normal to me. Detonation usually also causes the center electrode insulation to wear/crack and I don't see that. While a lot of people here claim that "balls of metal" on a spark plug are key signs to detonation, I haven't seen any evidence that "white, ashy" spark plugs like you have are signs of detonation.

Read the Spark Plug FAQ stickied at the top of this forum for more info. And if you are a real uber dork, check out www.prepsparkplugs.com as I found out about this unique plug while researching your question. In the end, I'd recommend NGK PFR7B (NGK Part Number 4853) and they are plats you drop right in with no gapping and long life.
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Old 07-16-2005, 01:54 PM   #3
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I use no fuel additives, and have been using Chevron 92 octane since I got the car. Occasionally I would use Shell V-Power 92, but that was a while ago. The plug did look more ashy then what the camera showed; I would have liked to take the picture in natural light since the flash seems a tad too bright. I guess I have nothing to worry about.

I did read through the (your) FAQ as well as most of the many "spark plug" threads, ( ) and decided that i'd either have to stay with stock platinum plugs or just go with copper. I figure that I don't need the durability of Iridiums if Platinums have lasted me this long... shrug. I picked up some Autolite 3923 Copper plugs, just to see if they'd work alright. I know they are cheap (read, POS, fram.), and honestly, i'd rather get a set of the stock NGK Platinums as I see hardly any wear, but the stock ones are pretty pricey.

One odd thing that I noticed was for one, the gap was set at 0.042 or so, very wide. The top of the plug that connects to the coil pack was different in a way that it has a hole, instead of a flat surface for the spring to contact. I'm not sure that the lip right around the hole is enough for the spring to catch, or if the spring goes inside the hole, but I hope it isn't a problem. Also, I gapped them to 0.028 to hopefully start out with 0.028 and even out to the 30's or so when it comes time to change. I searched more after I bought them, and for some reason I believe these plugs also fit on Dodge Dakota trucks?!?! I did a quick google and there were forums with truck owners talking about how their "Autolite 3923's" were better then their Bosch +4's ...?.

Well if worst comes to worst, and my car runs like crap, I guess i'll have to suck it up and buy only NGK. These cheapie coppers cost about $5 for 4. I just hope the spark plugs won't cause any problems from being gapped incorrectly. I also figure, since this is my first spark plug change, if I have to take these out, i'd get better at spark plug swaps.
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Old 07-16-2005, 04:47 PM   #4
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Just changed em out, the car seems to run fine. I guess if any abnormalities occur, it'll occur within the next few thousand miles, since most spark plugs seem great until "all of a sudden" everything goes down the john.

I might be able to snap a few pics of the rest of the plugs for the heck of it.

When torquing the new spark plugs in, it seemed tight, but when using the torque wrench set to 14 ft-lbs, the plug kept turning a bit. This worried me as the last thing I want to do is strip the threads on the head, so I backed off when I deemed it was tight enough. I'd like to be optimistic, but I think the little crushable washer / gasket on the plug was crushing, making it seem like I was going to strip the head, but wasn't.. ? I just left i though. Better safe then sorry huh.
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