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Discussion Starter #1
I'm trying to get my girl back up to "code" here after she turned 100k. Trying to figure a few things out.

I change plugs every 10-15,000 miles. Each time they look like they do in the following pic. This current pic is after 13k miles.
Can I get some opinions as to what is causing all those deposits on the plug? :bow:


tia,
Harry
 

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Maybe this will help:

http://www.mztech.fsnet.co.uk/workshop/wrk_plugs.html

According to the pics, it looks like your plugs are



A white coloured plug is caused by engine overheating. Failure to repair this engine will result in severe engine damage. Common causes for this are:

* Incorrect spark plug (too hot heat range).
* Low octane fuel.
* Timing is not set properly.
* Cooling problems, (dirty cylinder fins, no or low water if water cooled, low or no engine oil).
* Carburettor air/fuel mixture is too lean (too much air).
* Leaking crankshaft seals, no oil, base or head gasket leaks, or crankcase leaks on two stroke engines.
Has someone been using 87 octane? Hmmmm? :p
 

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Discussion Starter #3
No.......no 87.......ever!!! :p Only 91 and above. And that plug in your example looks different, no? Its top is still white; mine's covered with deposits.

I'm about to go check out that site though
 

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Looks pretty normal to me and you're replacing them needlessly. If you want perfectly clean spark plugs you'll need to nix your EGR and PCV systems and run better fuel.
 

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Looks like the engine is running a bit rich to me. My plugs weren't nearly that fouled at 40k, and there's no way the fouling should be that bad at 13k. Some questions:

Are all the plugs uniformly fouled?
Is the fouling more black or more brown in color?
Can you wipe it off fairly easily?
Do you have a clean air filter?
Are you chipped?
 

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HermanH said:
What the hell is that???? CORN MEAL????? :)
To be honest, looks a lot like sulphur deposits from the fuel. I find that rather odd though. The color of the electrodes actually look good (tanish brown to grey color).
What fuel do you use (vendor)?
Actually I was thinking carbon deposits... it is a common issue in airplane engines, as they are designed to be run at high RPM for long periods of time (idling on the ground causes spark plug fouling due to the rich fuel component and lack of air)

You may want to check your Air to Fuel Ratios.
 

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It looks to me also mostly like some built-up carbon. It could be just that you've been taking shortish trips in the cold? Make sure you take the car out on the highway and put the hammer down at least once a week. German cars need exercise.
 

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RechtsFahren said:
It looks to me also mostly like some built-up carbon. It could be just that you've been taking shortish trips in the cold? Make sure you take the car out on the highway and put the hammer down at least once a week. German cars need exercise.
My car acts like it has thunder thighs sometimes, others, its peppy. I excercised her at 90mph on a country road tuesday.
 

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wchp said:
Here is the MOTHER of all spark plug diags. The definative "How to read your plugs" if you will. http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

I am thinking your plug looks like image #6 or #8 (more on the "to cold/rich" side of things rather than the "to hot/lean")
Funny, I think it looks like that #9-10 (Good) :D I maintain that there's nothing wrong with the plug pictured and I'd probably hit it with a wire brush and per 'er right back in.
 

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Discussion Starter #14
jwil said:
Looks like the engine is running a bit rich to me. My plugs weren't nearly that fouled at 40k, and there's no way the fouling should be that bad at 13k. Some questions:

Are all the plugs uniformly fouled?
Is the fouling more black or more brown in color?
Can you wipe it off fairly easily?
Do you have a clean air filter?
Are you chipped?
Yeah, this is what concerns me. It's not that the plugs look like this, it's that they look like this at 13k that has me wondering. If yours looked like this at 40k, and mine look like this after 13k, something's weird.

To answer your q's....

-Yes, the plugs are uniformly fouled.
-The fouling is actually dark brown/black with those little whit-ish deposits on it.
-The deposits can't be wiped off, though a wire brush may work, they're on there like a powdercoat. Actually, they ARE a powdercoat, literally.
-Very clean air filter. K&N w/ ~10000 miles on it.
-Chipped, always. Don't leave home w/o it! :wink: APR v.3


-Harry
 

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Discussion Starter #15
Macabre said:
wchp said:
Here is the MOTHER of all spark plug diags. The definative "How to read your plugs" if you will. http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

I am thinking your plug looks like image #6 or #8 (more on the "to cold/rich" side of things rather than the "to hot/lean")
Funny, I think it looks like that #9-10 (Good) :D I maintain that there's nothing wrong with the plug pictured and I'd probably hit it with a wire brush and per 'er right back in.
Thanks for the input, Mac. What do you think about the plugs looking like this at 13k though? Still good?
 

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I think your engine is running a bit rich. IIRC there have been some other people that had a similar experience running the APR chip. It's only slightly rich and I don't think it was a major problem, but I think the only way to fix it is a programming change on the chip.

FWIW, this is about what my plugs looked like at 40k:

 

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the second site says excess deposits can happen under light loads or light driving or excessive idling. This tells me that unless there is a problem you aren't going to high in the rpm range so carbon deposits are building up. Maybe drive a little more spiritedly or dont sit and idle for long periods of time :???:
 

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Your plug looks like "figure 6" on that web site, as does mine.
But I'm running a GIAC chip on my 1.8T, w/K&N, TT DV.
That yellow soot does look like sulpher! Or possibly sand/silica
from fine dust entering through the air filter? What filter do
you use?

I always clean out the carbon via Cheveron Techron every oil
change, and a thorough highway flogging. :D

I was wondering if anyone here who is chipped has either:
a. reduced the gap from say .32 to .28 (or somewhere in there) or...
b. changed to a hotter plug?
 

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SDPassatT said:
Thanks for the input, Mac. What do you think about the plugs looking like this at 13k though? Still good?
If the deposits were a new phenomenon I might be worried about blowby but since they've always looked like that it's probably just a symptom of your driving habits. Maybe try going one heat range hotter if you're concerned about how they look or just try leaving them in a bit longer :)
 
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