Wow, what a pain! I have been getting all kinds of conflicting info on this, and it doesn't help that Ford changes the part numbers often apparently.

Truck in question is a 2004 5.4 3v. Non FFV obviously.

When the VIN is run on the Ford website it gives a 421 number, but the guy at the Ford dealer that I usually REALLY trust to seriously know his stuff sent me SP-507 PZT14F plugs. I know that the PZT14F part makes sense from the searching I did, but why the 507 instead of 421?

Can anyone verify this please?

Thanks!

 

421 should be the upgraded plug for the 5.4 3v

 

I just looked at the box mine came in and all it says is PZT14F

 

Spark plug numbers change elevenity billion times over the product lifecycle. So long as the second part of the number is 1F, you're good to go. The latest level plug I think now is like a PZT-1F-F4, or SP507.

 

I love the word elevinty

 

Quintin, are you sure about that? I thought that the lastest service plugs were the PZT-14F's...which are supposed to have a heat range between the 1F's and 2F's...???...

 

I searched for my 2004 5.4 3v and it says the part number is SP421.

 

I believe the SP421's are the PZT-2F plugs. Those are the factory plugs. However, they have been superceded for the 2004+ 5.4's by the PZT-14F's.

 

So it looks like the PZT-14F are the plugs to get! Im thinking of doing mine soon. I have 69,000 Km on mine right now. Which is 69000 km = 42874.612 mi. So there still pretty young plugs i guess.

 

I'm still waiting on FordTech1 to let me know where in PA he is. I'm hoping he will do mine.

For those who have done it, should I do it with my abilities? I can change oil, brakes, install my CAI and wheel bearing ***'y. Is it any harder than those(given I can read the TSB)

 

You can probably do it. It's working with the aluminum heads that scares me.

 

It's the spark plugs that scare me.