Hi Guys,
Am I wrong thinking that if a COP is bad it wouldn't run fine for 2 hours around town then start sputtering & misfiring? Then it's ok the next day for awhile.
I'm thinking that it's a plug that gets fouled after driving awhile not a COP.
I bought used 6 months ago. 2001 5.4 145,000 miles.
Just wondering if I should change COP's along with changing plugs.
Was running terrific until a few days ago.

 

Sounds like a cop to me. If you can get it to misfire while its idling, you can go under the hood and one at a time disconnect the cop's. Look for one that doesn't change, good ones will make it run worse when disconnected. You can also do that with your injectors. Cop's when they're going bad can sometimes only misfire when they want to. You can get whole sets on ebay from global automotive or uneek for around $100 for the set. Lots of people on here run them. With 145k, your probably due to at least inspect the plugs before one blows out, replace with motorcraft oem plugs if your going to. Make sure to use 28ft/lbs and NO antiseize on the threads.

 

Thanks Toyz,
I've got the Motorcraft SP479 plugs to replace. I didn't know COP could work fine and then stumble badly then be fine again. I thought if they were bad they would just continue to be bad. It looks like the COP's from Global & Uneek are from the same manufacturer. They show the same picture of "set of 8" on their websites.
I've emailed Uneek asking if there is a difference but haven't got a reply yet.
Thank you for your input.

 

I have one thats going bad right now. But it has been fine for 2 days. Few days ago it was misfiring pretty bad and at one point it was misfiring while idling so I pulled into a parking lot and found when I pulled the number 6 cop that it didnt change anything. So I knew it was that. But just hours later it went away. Then came back a few times at random intervals. Has been running like a champ for 2 days now though. So I'm still driving it, waiting for cop's. Never threw a CEL either. Sometimes they act like that when theyre on their way out. And it only takes 1 bad one to make it stumble pretty hard. Mine was shaking the hell outa my truck.

So I would say theres a 75% chance its a cop, without any testing to say so for sure. Hows your fuel filter and other maintenance?

I see your from Bend. Have some family down there

 

That's exactly what mines doing. I bought truck last January with 143,000 when I was down in LA area. The guy in Jan 09 @ Ford flushed power steering fluid, oil & filter changed, fuel filter changed,replaced wiper blades, machined rotors, replaced pads, flushed brake system, rear differential service, flush (auto) transmission, flush cooling system, flush power steering system at a cost of $1,068.63. Also in Oct 09 @ 139,694 miles he bought 4 new Bridgetone tires on Panther alloy wheels and aligned the front end. He followed up the Ford service with Jiffylube in Oct 09. I feel good with the maintenance he did with truck. He also owned a late model Porsche and a BMW that also looked well taken care of.
I plan on the plug change and COP change just deciding on what COP to order. Granatelli's look good but costly. Would like to save with Uneek or Global but I'm concerned with China product. Where did you order yours? I love the truck. Your family might have come into my store, I have a Retail Home Furnishing store (Periwinkle Home) that was downtown Bend but now selling off Craigs list & word of mouth.
Thanks again for your help,
Bob

 

Get the Global or Uneek cops, and get the V-10 set so you have a couple spares. They are OEM quality. Granatelli cops are not reliable.