my buddy has a 98 f250 with i believe the 5.4. it runs terribly rough and gas milage is real real bad!! we have replaced the drivers O2 sensor (before the Cat) cleared codes and it was fine for a few days. then we ran some seafoam through the intake and again it was fine for a few days, now it is worse then ever. any suggestions, and just what is bank one? I was told drivers side? from what I can tell code 1131= lean o2 sensor, 1132 rich o2 sensor, 1133 sensor not switching (all from bank 1) and 0133 Bank 1 slow signal? any Ideas? truck has about 125k on it

 

Looking into the engine bay the cylinders are numbered like this
4 8
3 7
2 6
1 5

Sidewinder

 

It is the O2 sensor on the passenger side in front of the cat. Disconnect it and check the connector for corrosion. make sure the wires going into the Sensor are not loose or corroded. If that checks out look for loose connections in the air intake. Check the PCV piping for leaks. Has any work been done to the truck reciently?

JMC

 

nothing has been done to the truck. Auto Zone told him it was the drivers side o2 sensore so replaced it for him and disconnected the battery to kill codes, the light did not come on for 2 days, then we ran some Sea foam and carb cleaner through the intake and vac lines to clean it all out, disconnected the battery again and the light stayed out for 3 days (only about 30-40 miles though) now it is real rough running and autozone pulled and cleared codes and the light come right back on. I assume it needs the other o2 sensor since they told him the wrong one, i will replace the pass side sensor and see what happens. the code 1131 and 1132 lead me to clean the intake and vac lines but I was assumeing we replace the correct o2 sensor. no air leaks i could find and lines look good, intake was very dirty but the truck has 128k on it, so overall in good shape.

thanks

 

Take the old o2 sensor from the drover side and put in place of the passengerside sensor. If it kills the codes then you can leave it in ( I wouldn't ) or you can replace it with a new one as a maintenance procedure. FYI I change mine every 50,000 miles.

JMC