Can anyone tell me the difference between the motorcraft sp421 and sp462? The 421 is specified for '04-'05,the 462 for '06-'07. Would it be better to replace the plugs in my '05 with the newer plug?
Thanks

 

Without knowing what the exact difference was, I chose to install the newer Motorcraft SP-462/PZT1F plugs in my 2006 5.4 3v SCREW. I am hoping that the bond between the electrode shield and the plug body is stronger, but don't know that for fact. I received mine from RockAuto for a total cost of just less than $80.00

Regards,
Russ

 

I'm pretty sure it's the heat range. I only know them by the numbers on the plugs (PZT---)
Put the SP-462/PZT1F in when you change them.
And don't forget to follow the TSB, but allow more time for the penetrating oil to soak in.

 

Thanks for the info-I have found them locally for $8.(the dealer wanted $17)
Is there a substitute for aerokroil?

 

Why would Ford spec a lower quality plug to be reinstalled?
Could the plug difference be due to changes to engines designed to be FFV (85% Ethanol)? Which are the 2006+ 5.4L 3V
I purchased the SP-421 per www.motorcraft.com AND www.rockauto.com
Can anyone verify what the difference is between SP-421 vs SP-462?

 

I purchased the sp421 today locally, compared the 2 plugs, no apparent difference, parts man looked it up in Motorcraft book, said 462 is colder plug. He also recommended PB Blaster for penetrating oil.

 

What is the number on the sp421 plugs? If it's PZT2 I wouldn't install them. Go with PZT1F
It has nothing to do with flex fuel or a lower quality plug.
PB Blaster is a good penetrating oil but I've never used it to remove these plugs, only Kroil.

 

sp-421= pzt2f
Is there a problem with these? Where did you purchase kroil?

 

I just removed my plugs in my '05 SCREW after 40,000 miles. I purchased the Kroil penetrating oil form Midway Auto Supply Inc. through Amazon.com. Total cost with shipping about $13.50. I used it liberally and let it soak several hours and went very slowly and with caution. If the plug was very tight, I just went on and came back later. Got them all out without any damage.
Russ

 

I checked the SP-421 plugs...they are PZT2F, not PZT2.
I remember reading a thread stating a TSB about using PZT1F plugs, but that was for a knocking issue (if I remember correctly?).

Is there a difference between PZT2 and PZT2F plugs?

I don't want to second guess Ford. Why would my local Ford dealer tell me to install the PZT2F's, as well as www.motorcraft.com, as well as www.rockauto.com, etc if they are not the correct plugs to use?

Just curious if anyone knows why one should use PZT1F instead of PZT2F on the 2004 and 2005 5.4L 3V.
FYI: www.motorcraft.com does state to use PZT1F on the 2006+ 5.4L 3V.
But for 2004 and 2005's its PZT2F.

 

You can buy it direct if you want, http://www.kanolabs.com/, or find it on Amazon even.

 

Just use the PZT1F's, you aren't going to hurt anything, I have a little inside info
And there is a TSB 06-3-3 that states to remove the PZT2F and replace them with PZT1F plug.

 

Is the PZT1F one heat range colder then the PZT2F?
Anyone know why Ford recommends PZT2F for the 2004 and 2005 trucks, then PZT1F for the 2006+ trucks?

TSB 06-3-3 does say the PZT1F's are the "latest" plug....and should be installed instead of the PZT2F's if the truck is knocking.
So why aren't the PZT2F plugs superceded? Why does Ford still recommend installing the PZT2F's on 2004/2005 5.4L 3V engines?

Knocking will be minimized if you run a colder plug...

 

the PZT1F is a colder plug than the PZT2F. Autolite also offers a plug that is even another heat range colder, the HT0

 

Thank y'all for the info-took the sp421(pzt2f) back and got the sp462(pzt1f). Recieved 9/16 plug socket from Sears today, may try to change them Sunday.