I got about fifteen minutes away from my house when all of the sudden my '98 4.0 Ranger started misfire badly. I took it back home and changed all my spark plugs and wires, but it is still misfiring. When i changed the plugs i found that my 1 plug was covered in oil. Im going to do a compression test in the morning and im hoping i dont have a holed piston or a cashed valve... I was wondering if anyone else might have any idea what is wrong. id appreciate any advice or ideas anyone might have. thanks a lot guys.

 

if it happens on deceleration only then it could be your air injection. if not then it could be your valves not sealing or your timing is off. ofcourse if it was your timing then you could check. good luck.

 

it ended up being a hole in my #1 piston. i have a new engine coming from a wrecked '00 ranger with only 31,000 miles on it