I just noticed after ordering replacement spark plugs online that the ones previously sent to me by an EBay seller were the wrong ones. The ones he sent were for the "Lightning" 5.4 V8 F150, not the standard. It was one of those deals where you buy the COP's and they give you a set of plugs to go with it. He claimed they were the right ones. I still should have checked.

Comparing the two plugs (the standard and Lightning), the required gaps are different. So if I was going off of the standard gap but using the Lightning plugs, I would have had the gap set wrong from the start.

I have been using the plugs for about 7 months. The truck right now is running terrible. It began running rough after a rain a ways back. I replaced the COP's a few months back but it did bot fix the problem. Now I am going to replace the plugs.

Does anybody know what running the "Lightning" plugs in the standard 5.4 V8 does to the engine?

Thanks.

1999 F150 XLT, 5.4 V8

 

Be sure and use dieltric grease on the boots.

 

Hi.

Pull them and replace with Motorcrafts (OEM platinum plugs) - they are ony a few bucks each (Rock Auto). Gap as per OEM spec for a non-boosted engine.

Running a Lightning plug - which is likely a colder one and will foul easily, in addition to the smaller gap spec - to minimize blowout under boost, but is less efficient in a N/A engine - is not good, as you can now attest.

EDIT - X2 on BJ's advice.


Callin' the Big Guy ...





MGD

 

How about telling us the brand and part number for the plugs that you are using?

The recommended plug for your engine is Motorcraft SP-479 (AGSF22WM or AGSF22WMF4), .054 gap. The Lightning plug is 1 heat range colder with a .044 gap.

That's most likely a COP problem - possibly due to not using dielectric grease correctly when installing them. It's possible that you have a leaky hood seal and you got water directly on the cops. The cops may or may not be damaged now.

 

Yeah I always use dielectric grease on the COP's. The plugs that I am running now are Motorcraft SP-495. The ones that I bought to replace them are Motorcraft SP-479. Yes it's running like hell now. I'm almost sure it has to be fouled plugs, since the COP's have been replaced.

Damn that pisses me off that the EBay seller sent the wrong ones. Still my fault for not checking I guess. I just hate having to go through the process of replacing them again.

Thanks for the help guys.

 

Yep, the SP-495's are 1 heat range too cold. If you pull them, they will probably be fouled.

 

Same thing happened to me. Purchased one of those Plug & COP deals on eBay and they sent the wrong plugs lol.

I just ran them up to local parts store and they swapped them for the correct plugs.

That was long ago, I purchased these for a buddy's 99, back when Global first started selling Ford ignition parts. -