Ok, so alot of you know i have been having alot of issues with my 4.0 for the last few months.. Finally got it to stop misfiring and throwing codes after i changed the coil pack. But something still isnt right.. I pulled the plugs on the pass side of the truck, and the #4 one was very bad.. The actual contacts wernt bad, but the threads were completely caked with some sort of residue.

I switched the #4 plug with the one next to it( instantly started running better), and took her to the ford dealership for a diagnostic.. Everything was running fine according to the computer.. the one thing that he did see was the plugs ( all of them) would dip down below normal range spuradically..

He suggested that the fuel on base is causing this because it is of crappy quality and to fill up off base, so i did( i was on E), and it seemed to work for the next to fill ups, although the second time i filled up it didnt run as good as the first time, and the third time i had to fill up on base, and she was right back to running like *** again..

So, heres my question,

could the fuel on base be causing my engine to run like complete ****? It has NO power, exhaust is way quiter than it should be, and its getting HELLA BAD gas mileage.. im talking i got 190 miles to the tank on my last fill up ON base.. I WAS ON "E" again.. running on fumes..

 

It very well could be the gas.
Around here the Indians sell 85-86 octane , whenever I run it my mileage takes a dump.
I've found through the years that new vehicles , cars and trucks, average 400 miles per tank when new. No matter tank or engine size. I use that as a gauge as to how the engine should be running , and it hasn't failed me yet to alert me to a problem.

You may have a dirty injector problem , compounded by the fuel you're running.
If it were me , I would pull the injectors and clean them.

 

the fuel could have ethanol added to it

i noticed that will my old 3.0 litre engine

engine ran rough and mileage went down big time

try pouring 2 cans of injector cleaner in with you fuel

but you are better off getting the injector power flushed at the dealer

your cylinders may not be getting enough fuel
( the computer can only compensate so much )

 

thanks for the reply but dont have the ranger anymore haha. It ended up being a cracked head