Revised Spark Plug

[frdwrnch]

New service message this morning revising replacement spark plugs for 4.6L 4V Mustang, Merc. Marauder, Aviator and Navigator. These vehicles are currently using AWSF-32E-M and AGSF-32W-M. "Whenever the spark plugs require replacement use part number AGSF-32P-MF4."
These plugs are a full thread design and are less likely to sieze up or blow out but they still bottom out at the same point.

[jgc61sr2002]

Originally posted by frdwrnch
New service message this morning revising replacement spark plugs for 4.6L 4V Mustang, Merc. Marauder, Aviator and Navigator. These vehicles are currently using AWSF-32E-M and AGSF-32W-M. "Whenever the spark plugs require replacement use part number AGSF-32P-MF4."
These plugs are a full thread design and are less likely to sieze up or blow out but they still bottom out at the same point. frdwrnch - Do you recommend changing the plugs at this time or to wait for the prescribed interval? Thanks John

[frdwrnch]

I would not change the plugs unless you have a performance problem such as a skip. But if one developed, I would probably change all of them.

[JamesHecker]

What do you think about changing to the Denso Iridiums?

[Sidney]

Could a slight shake, every few seconds be considered a skip?

[FordNut]

When I changed to the Denso plugs I noticed the difference in the threads and posted comments. The Denso plugs are threaded all the way to the end instead of having the unthreaded "step" like the OEM plugs. Sounds like FOMOCO is finally catching onto the idea that maybe there isn't enough contact area with the original design.

[Blue Marauder]

Do the Marauders have a problem with blowing the plugs out of the heads like the Lightnings do?

[frdwrnch]

I recommend the Denso plugs. I use them myself. I don't know of any Marauders blowing the plugs out but the heads and plugs are the same design as the Lightning that has this known concern.

[frdwrnch]

Sidney, it is possible that you have a skip but they are usually noticed more under load (heavy accel., going up hill, etc.). It feels like a hard "bump". If in doubt, stop by a dealer to verify if it is readilly duplicatable.

[Blue Marauder]

Originally posted by frdwrnch
I recommend the Denso plugs. I use them myself. I don't know of any Marauders blowing the plugs out but the heads and plugs are the same design as the Lightning that has this known concern.

The Lightning is a 2-valve, SOHC motor vs our 4-valve DOHC motor, so the heads are hardly of the same design.

[frdwrnch]

Your right! Had a senior moment, but the plugs seat the same and I would definitely go with the full thread design as these will chase their own threads when removing and installing.

[jgc61sr2002]

Thanks frdwrnch - I'll leave the stock plugs and change to denso when the time comes .:up:

[Pantherman]

With the old design, stresses are concentrated on the very short gap between the head and the end of the plug thread. The new design spreads the same stresses over many more threads, allows more "stretch" in the plug, and gives a more reliable joint.

[engine23ccvfd]

he said "joint"