Just changed out the original factory plugs and found that 2 different kinds were installed. The right-side head had Motorcraft AGSF-34EG Platinum plugs. The left-side head had Motorcraft AGSF-34E Platinum plugs.

The electrode tip was completely gone on the 34EG's yet the 34E's had some of the electrode tip still in place.

I've had the truck from new and this is the first time the plugs have been changed.

Any ideas on why this might have been done?

Are these just different heat range plugs?

................Scott

 

These engines have different spark plugs installed on each side at the factory.

From the Ford Manual, for the '97 4.2L:

Application and ID:

Right Side Original Spark Plug AWSF-42EG

Left Side Original Spark Plug AWSF-42E

Replacement Spark Plug (Either Side) AWSF42EE

 

Interesting, so I gotta wonder what's going on different between the left and right sides..........................?

.................Scott

 

If you actually look at the factory plugs, one side has the platinum on the tip and the other has it on the electrode due to the waste spark ignition setup. The replacement plugs have platinum on both the tip and the electrode so it doesn't matter which head you put them in. Basically, Ford is saving a few cents on each plug doing it that way. A few cents times a few hundred thousand F-series trucks adds up.

 

Might as well add in the few hundred thousand Tauruses, Mustangs, and the rest since they do that across all the product lines when platinum plugs are used.

I wonder how much it *REALLY* adds to the bottom line - compared with stocking two part numbers, etc.