I bought Motorcraft spark plugs (SP-500 AGSF22FM) for my 1998 F150 5.4 about a year ago on the internet. Forget what parts store it was. Now that I've reached 100K I've started changing the plugs, changed 4,5 and 8 cyl's before noticing the old plugs were AWSF22E. Checked Motorcraft and found that AWSF22E is recommended for the truck. The plugs look pretty much identical except the 22FM is has more threds but its the same length. I'm concerned that they may run hotter or something. Got any ideas?

 

Details are kind of fuzzy in my head. But as I remember, the spark plug was superceded to a plug that has more threads.. I think this was done to help with the spark plug popping out issues.

 

I was under the impression that the pi heads had 8 threads on the heads, the non pi heads only had 4. Please correct me if wrong.

 

The only 8 thread heads are '03s. That is just a superseded number, most likely when the '03's came out with more threads

 

I think I bought the plugs at Amazon.com.. Anyway I've check with motorcraft and they don't match what motorcraft recommends so I removed the three plugs I'd installed. Auto Zone gave me credit for the five AGSF22FM plugs but they only carry Autolight 103's. Anyway I've replaced cyl 5,6,7 & 8 with the Autolight plugs and if it runs good for a week I'll do the other four. Number 7 cyl was a chore without removing the fuel rail. Thanks for your reply's but I didn't want to be thinking every noise I hear from now on was due to the wrong plugs....

 

I bet autolite 103's will cross reference to the AGSF22FM. Once they supersede numbers you aren't able to get the old ones unless someone has some old stock.

 

I have not been able to find a cross reference that says the AGSF22FM is what Ford recommends for the 1998 5.4. What I find on the Motorcraft site is a SP405 or SP479 is recommended however at Auto Zone the SP479 (I think) stated something like two plugs per cylinder. Long story short, if Motorcraft wants my business, they need to make it clear which plug is the repalcement for the AGSF22E.