Hey all, can anyone diagnose my spark plugs. I pulled them out after only 5k miles and the ends seem all black (above the threads). Is this normal? I'm running 10.6:1 compression, and these are NGK BKR5ES-11 plugs...

I don't have that high compression stuff you have there, but that's how mine looked like when I pulled it around 13,000 miles. So long as the tip is not coated in oil, I guess that should be fine. Sorry I couldn't be of much help!!!!

that 1st pic looks like it is running lean from the white tips... i change my plugs ever 1500 miles along with my oil and filter.

Are you talking about the curved piece at the top that looks lighter? That means I'm running lean? Also, the center electrode that is surrounded by the white insulator is pretty much black, just like the edge near the threads.

If your not running NOS, I would put in those P+4 plugs, those things are awsome, i recommend them to everyone.

I agree, from the looks of the top of the electrode on the first pic, it is a bit on the white side. That would indicate you are running lean. Not lean enough to cause damage but leaner than you want to for optimal power.

The way to confirm this is for you to tell us (since we can't tell just from looking at the picture) where the top of the electrode is white in that first picture, is the surface of the electrode a bit rough (not smooth like a new plug)? If so then you are running lean.

If it is just white and still smooth then it's moer likely the gas you are using (high MTBEs), but if that electrode surface is slightly rough then you're lean. My plugs looked almost identical when my SAFC was wired incorrectly and the car was running lean all the time.

The center electrode and the threads are black due to normal combustion. Because there is some black in there along with the top of the electrodes being white, that would also suggest you aren't causing any damage. Still, I'd check to see if you can get that air fuel ratio a bit higher. Are you getting a check engine light? Do you have a SAFC?

Todd, how did you have the S-AFC wired up wrong?

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Looks like your running lean a bit more than usual. Noticed burnt marks on the base of the insulator(SO you been major racing.). Looks like starting to overheat the engine. Listen for any faint detonation(harmful to engine) if your on AFC. Slightly richen a bit. Else switch to colder plug(Brk 6E's)

I think your plugs are running a little on the rich side. Check this faq from ngk:

http://www.ngksparkplugs.com/techinfo/spark_plugs/faq/faqread2.asp

You should have a slight grey but smooth coloring on the tip. If your tip is black or oily, you are either running too rich or have an oil/coolant leak.

What gap are you running? If i were you, i'd go with 7ES range. You are running one hotter range than stock. Stock is 6ES. You definitively want to go colder with turbo. I've also found that with my stage 2 HRC kit, i have to run .030 gap versus the .035 mainly because i'm running way rich.

go ahead and change them. It can't hurt to change, and could be better off. PLugs aren't that expensive. Unless they are denso iridiums.

Thanks, I saw that site too so I figured rich since the tip is black (but not oily). I will go check on the top surface to see if it is rough later today. BTW, I'm not turbo. Just ported and milled head for 10.6:1 compression, AEM cam gears, intake, headers, exhaust, etc. RRE had the "5" plugs gapped from 0.028 to 0.030" because it idled really bad with a bigger gap. Right now, I put in the stock "6" heat range and gapped at about 0.034". It does idle worse than before. When cold, the idle fluctuates along with my a/f gauge. Like when the gauge spikes up, the idle jumps up a little too, then goes back down. But after it's warmed up, it's normal. But I don't have a SAFC. Would it be worth it to get one? I'm not good with wiring or tuning though...thanks.

well that plug looks good to me. The edges are black meaning your running to cold or rich. General things to looks for are the colors and the condition the plug is in. The condition looks good the electrode is still in good shape.

White= Lean/HOT
Grey= Just right
Black= Rich/COLD

Oh ok you dont ahve a turbo. Sorry. Yes you definitively want to stay in the 6ES heat range.

Do you have an upgraded fuel system? (fuel pump, etc) I had 12.5:1 compression on my engine a while ago and my plugs were fine with stock heat range, gapped at .045.

Thanks, I have stock fuel pump and everything. I forgot I don't have my car this week, so can't check the old plugs til next week. I guess it's running rich then right? It can't be too cold since that was the 5 series plug...

Ok, just remember if the surface of that electrode is a litle rough, then you ARE running too lean. I seriously doubt the car is running rich.

And Mike, I didn't connect the SAFC to the computer via the MAP sensor wire correctly. The connection got worse over time and caused me to run lean and get a check engine light (there was essentially a poor signal, or no signal, getting to the computer fromthe map sensor)

It's fixed now, no check engine light, and the SAFC is doing it's job exactly like it should. I probably helped contribute to me dropping my 1/4 mile time by just over a tenth the last time I went racing.

UPDATE: I just checked my old plugs, and the top of it is "rough". There seems to be a whitish brownish crusty layer on the top of it, where it looks kinda white in the picture. Basically, it is mainly a white colored rough layer, with a bit of orange or brown on the edges.

So does this mean I am running lean? I thought our cars usually run very rich? BTW, these were NGK BRK5ES-11 plugs gapped at under 0.030". Thanks.

Oh also, I just replaced my o2 sensor a few weeks ago because the a/f gauge was showing very slow responses, and sometimes it would just show 0 or 1 bar at idle. But at WOT, it would still read normal with 8 to 10 bars.

Spark plugs don't lie :)

Yes, you are running on the lean side. That rough eletrode surface confirms it. From what the plugs look like, I'd say you haven't done any damamge to the engine. You are just running leaner than you'd want to.

Now, the slow O2 sensor was probably causing it. Remember, only a very small amount of time is spent at WOT. Most of your driving is at a cruise at about 10-15% throttle or so. At those speeds, the car is always trying to set the A/F ratio right on the stoichometric edge for emissions. If the O2 sensor is slowig down on you, then the car isn't getting the right signals of what is actually going on and it could cause the car to be a bit slow in adding enough fuel and cause a lean condition.

I'll bet your A/F gauge is showing normal readings now during normal driving. If you check the plugs a few months from now, they'll probably look normal.

Thanks, that makes perfect sense now. Now I have another related question though. I pulled the new plugs yesterday and tried gapping it smaller to 0.030" (I gapped it to 0.034"). The reason I tried gapping it smaller was because at idle when it was warming up, the engine would jump about 100 rpms every time the a/f ratio jumped on my a/f gauge. Then it would drop as the a/f ratio dropped. So the idle fluctuated as the a/f ratio changed. What might cause this?

Now, with the smaller gap, the idle is even worse (I was told it might be because now I am using the 6 heat range plug instead of 5). Or did I maybe damage the plug by trying to regap it? Does anyone know if a bad idle may be caused by too small of gap? Thanks a lot.

You're plugs indicate that you're running rich... Carbon fouled, and with the 5 heat range it should be heating up faster... just gap the plugs to .50 to .54. Smaller gaps can affect idle although not much, but you're probably getting most of the rpm flutter from the carbon fouled plugs... you should be aiming for grayish brownish color...

Ro

Thanks, I actually just changed my plugs, and the new ones still cause a rougher idle. Right now I think I found a good gap at 0.036". The idle is bearable (won't stall) but I still get a popping noise if I hold the revs at 3k rpm in neutral. So I think I still am getting a misfire, which means I might need an even smaller gap right?

BTW, how do you guys make the gap smaller? Do you just hit the plug onto a hard surface? When I make the gap too small, it does not seem to be parallel with the center electrode anymore. It tends to curve down so one side is lower than the other...

Mine pops with no load at around 2500-3000RPM. Nothing to wory about, its just advanced timing with no load..