Hi everyone new to the site and I'm going to give a good question for you all!
I just picked up this prestine 1997 F-150 long bed XLT std cab 4.6L (W)auto Tranny.. Test drove it ran fine like new! The guy who had it before me used it in a private powerwashing buiss. and put 150,000 mostly highway miles on it.Which, I might add didn't scare me the way it ran and was so clean (no leaks or signs of). But after i bought it I went about a normal tune up and pulled the first (toward the grille) plug on the pass.side and it had Auto lite double platnium plug in it and it looked like hell! Not to mention I thought the platnium plugs were pre gapped for the engine application when bought.These plugs are gapped at .045 !! and so corroded ,white deposit build up and white tipped!looks like someone blew frost all over the tip! I can't belive how much deposit build up I chipped away off these! I guess I need some advice on what to put back in this and what might be showing from the signs of this plug.Like I said it runs like no other but it does stumble a little at times at low rpm or has a gitter at idle every so often. I was so surprised by this I took pictures of the plugs,sorry I don't know where to begin,or how to put them in this post....tried searching but can't find a whole lot about it on the site to walk me through (The [img] confuses me or I thinking to hard) I'll have to ask my 3 year old!

 

Put a new set of stock Motorcraft plugs in it.

 

Do a search here on spark plugs, plenty of info to let you know whats going on

 

It sounds like those may actually be the original plugs. What your seeing is normal wear and tear caused by the amount of mileage they've seen. The previous owner could have been using fuel additives regularly that would have caused the deposits on the plug, or, they were replaced at some point with a colder plug. This would cause the deposits to build up because they aren't getting hot enough to self clean.

Your best bet is to find out the proper plug for that engine, replace them and check again in about 6 months. Stay away from fuel additives, and use a good grade of fuel. If those deposits return then you may have to do some investigating.

 

Thanks for the replies! I tried seaching and came up with alot of variations,just wanted a input on my situation.

Tbird69,Thanks for your input, sounds like you have some knowledge when it comes to looking at plugs . I'll go down to ford dealer and see what plug they say to use. They had APP104 autolite in it and I don't know the mileage on them but it looks like they were mis gapped and alot of poor fuel used.

 

Learning how to read plugs has saved me countless hours of troubleshooting when I'm rebuilding old engines.

When you get the new plugs, if they are hotter then what you took out, don't be surprised if now you get some light pinging/knocking when accelerating or pulling a load. The colder plugs may have been put in to "fix" an EGR system that wasn't working right. If the new are the same as the old then no worries, just check them in a few months.

I'm not trying to scare you, just a heads up.

 

104 is the plug they always told me to get. mine always came out black and burned...

 

I think with these plugs being gapped wrong (which is .010+ off ) and low octane fuel (87) and alot of highway miles caused this. It doesn't burn any oil,the engine is tight.