Why did spark plug part# change on newer 4.2?
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Why did spark plug part# change on newer 4.2?
I'm servicing a 2006 Freestar with the 4.2 engine. The spark plugs that came OEM on this engine was a Motorcraft SP504 platinum (AGSF34FM). The manual and online part# only reference a copper plug, the SP506.
Strangely, for older model Freestars (2004-2005) with the exact same 4.2 engine, they reference a Motorcraft platinum SP486 (AGSF42FM).
Based on this spark plug decoder, it seems the newer SP504 is just a colder heat range plug:
MotorCraft Spark Plug Information - Jim's Site
So does anyone know why Ford changed the recommended spark plug part # for 2006 on the exact same engine? Why did the plugs that came factory on this engine (SP504) not even come up as a choice? I don't want copper plugs since it's such a huge PITA to do plugs on this van.
Strangely, for older model Freestars (2004-2005) with the exact same 4.2 engine, they reference a Motorcraft platinum SP486 (AGSF42FM).
Based on this spark plug decoder, it seems the newer SP504 is just a colder heat range plug:
MotorCraft Spark Plug Information - Jim's Site
So does anyone know why Ford changed the recommended spark plug part # for 2006 on the exact same engine? Why did the plugs that came factory on this engine (SP504) not even come up as a choice? I don't want copper plugs since it's such a huge PITA to do plugs on this van.
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stirfrysteve
1983 - 2012 Ranger & B-Series
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Feb 27, 2005 03:22 PM
