Because that is the colour that the engineers decided upon.
The spark plug number that is in my 2003 Ford Ranger XLT is: AGSF34FP - Motorcraft.
Second from the left.
the spark plug gap is .054in. for 2003 ford focus.
The recommended spark plug gap for a 2003 Ford Expedition 4.6 is .054"
On a 2003 Ford Mustang , 3.8 litre V6 engine : firewall 3 - 6 2 - 5 1 - 4 front of vehicle
stick it on the spark plug, its a coil on plug stick it on the spark plug, its a coil on plug
which side of the motor is the 1 plug on my 1989 ford!
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front
On a 2003 Ford Expedition ( 4.6 and 5.4 ) firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of vehicle
take it to dealer
The 2003 Ford Ranger Owner Guide shows .052 inch to .056 inch spark plug gap for the 4.0 liter V6 engine
Just below the fill plug... has 2 prongs sticking out attached to piggy back connector green wire and red/orange wire.