Yellow Plugs
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
Probably a cat just peed on them... 
How yellow are they? Like Mello Yello color?
It could be that some deposits got melted onto there. Perhaps the engine started running a bit lean while under a heavy load, but not enough to give it that white color?
Did you just buy this truck? If so, who knows what the PO could have added to the fuel tanks... octane booster, MPG improver, all sorts of snake oils.
How's the engine run?
How yellow are they? Like Mello Yello color?
It could be that some deposits got melted onto there. Perhaps the engine started running a bit lean while under a heavy load, but not enough to give it that white color?
Did you just buy this truck? If so, who knows what the PO could have added to the fuel tanks... octane booster, MPG improver, all sorts of snake oils.
How's the engine run?
Thread Starter
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New User
Joined: Sep 2014
Posts: 12
Likes: 0
Probably a cat just peed on them...
How yellow are they? Like Mello Yello color?
It could be that some deposits got melted onto there. Perhaps the engine started running a bit lean while under a heavy load, but not enough to give it that white color?
Did you just buy this truck? If so, who knows what the PO could have added to the fuel tanks... octane booster, MPG improver, all sorts of snake oils.
How's the engine run?
How yellow are they? Like Mello Yello color?
It could be that some deposits got melted onto there. Perhaps the engine started running a bit lean while under a heavy load, but not enough to give it that white color?
Did you just buy this truck? If so, who knows what the PO could have added to the fuel tanks... octane booster, MPG improver, all sorts of snake oils.
How's the engine run?
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
I was talking about a feline cat, the furry ones that pee on things. Lol.
Why did you replace the cats and o2 sensors?
I don't think your cats (converters) would cause plug fouling. Never seen it, but I guess anything's possible.
What heat range are those plugs? Try changing brands and/or heat ranges?
Why did you replace the cats and o2 sensors?
I don't think your cats (converters) would cause plug fouling. Never seen it, but I guess anything's possible.
What heat range are those plugs? Try changing brands and/or heat ranges?
Thread Starter
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New User
Joined: Sep 2014
Posts: 12
Likes: 0
changed cats because the truck got to where it wouldn't pull a hat off your head. mileage also dropped. pull pipes off exhaust manifolds and truck ran better. also had check engine light with a o2 code. sometimes i would get that rotten egg smell. replaced cat and things got a whole lot better for a while. then this problem started. been fighting it since.
Laughing Gas
Joined: Nov 2013
Posts: 871
Likes: 6
From: Orcas Island, WA
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Cargo Master
Joined: Nov 2013
Posts: 2,168
Likes: 3
From: South Central,MO
I don't think it has anything to do with the truck. I think it has to do with the environment you drive in.
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New User
Joined: Sep 2014
Posts: 12
Likes: 0
sorry i ain't been on in a bit. ok here we go. it is not enviroment. didn't happen until i replaed the cats. good thought though.the plug chart that krooser sent is close. there is no brown on plugs. it just looks like somebody took a paint brush and painted them yellow. it is on the outside of the plug on electrode, tang that hangs over electrode, and insulator at electrode. have tried different brands of gas. kroger, citgo, bp, exxon, shell, sheets, sunoco. also regular, midgrade, and hi-test. no change. also have tried non ethanol gas. little better, but not by much. also no check engine light. scanned it anyway. no KOEO or KOER codes. any thoughts would be appreciated.
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New User
Joined: Sep 2014
Posts: 12
Likes: 0
hey krooser. now that i'm studying your chart a lot better, 12 looks darn close. the only difference is the top electrode isn't brown, but same color as the lower electrode. bright yellow. any difference?
Laughing Gas
Joined: Aug 2002
Posts: 1,069
Likes: 19
From: Central Wisconsin
