i have a 2001 ford ranger 4cy 2.5 liter it has 8 plugs i know 4 are for the motor and other 4 are for the exhaust but which ones are for what i have no idea

 

Are you planning to change only 4?

 

i am only getting a slight heisitation i figured it was only the four for the engine

 

I am not sure which is which. What you can try is to switch the two on each cyl and do it for all four cyls.

 

This used dual plugs (and is a throwback from the 2.3L that used the same system for many years) to more uniformly ignite the fuel/air mixture. Both plugs fire at the same time, except on deceleration, in which case I believe the exhaust side is cancelled. Pretty amazing what they had to do to get this through emmissions, but it just shows how intelligent the engineers are. Two plugs and it was still a dog.