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ok so today i got to do a compession test and put new spark plugs and thanks to the faq section did it exactly described in those treads. Went pretty well took me 2 and a half hours, i think my numbers are pretty good.
I few things i noticed i had some white powdery stuff on #7coil and a little on #8coil. There was also a little oil in there and cleaned it up(leaky valve cover gasket i guess) mabye 4-5 drops in each head. It looks like they are the original plugs 67000ml THEY WERE DUE. heres some pics give me some feedback on what you guys see.the plugs are are in order from left to right cylinder 1 to 8
 

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Always good to get a compression test carried out !

My ones if you are interested :

Bank 1 : 185 psi, 200 psi, 190 psi, 185 psi
Bank 2 : 200 psi, 195 psi, 215 psi, 200 psi

About 117,000 miles or so when I had it tested. On 135,000 miles now. 1999 MY.
 

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Compression test looks good and like you said, looks like your valve cover gaskets may need changed. The white powdery stuff is a dielectric grease, I think, or it could be a little electrolytic corrosion deposit. It doesn't look like it was hurting anything in either case so it is probably fine. The plug tips look dry and clean. I think your engine is fine!

edit: is that rust on number 8?
 

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how much psi does the normal compression is ?
or its variant from one cylinder to other
 

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My compression numbers, 2001 95k miles:
#1 - 218
#2 - 215
#3 - 220
#4 - 220
#5 - 216
#6 - 222
#7 - 218
#8 - 217
 

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To be honest, I thought it looks like some uneven burn on the plug tips, and I might be consdiering some injector cleaner, or getting them ultrasonically cleaned but I don't claim to be an expert reader of plugs, so I could be way out.
 
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