Engine Misfiring on Bank 1

[Joshua Bowers]

Recently my 2003 Sport Trac XLT 4.0 started i misfire on bank 1 and threw codes P0300, P0301, P0302, P0303 and the o2 sensor read rich. I replaced the coil and nothing happened but it would only misfire under load and then again it would only do it every so often and not all the time. Now the CEL light stays on for the O2 sensor reading lean and its misfire has gotten worse. I replaced the plugs amd wires on bank 1 and it ran fire for a driving cycle then it started misfireing all through the driving range.

 

[Thadigus]

For clarification, you went from running rich to running lean just because of a change of spark plugs, wire, and ignition coil?

 

[Joshua Bowers]

No it switched before then, but i replaced plugs, wires, IAC, I cleaned the MAF sensor, and i replaced the coil about 3-5 weeks ago. Its currently showing codes P2196 and P0300. But no it didn't switch after i changed it did some time before.

 

[Ngrimm]

Bad fuel injector? If adding Seafoam to the fuel improves it then you will know.

 

[Joshua Bowers]

Bad fuel injector? If adding Seafoam to the fuel improves it then you will know.

I fixed it, it was an O2 sensor was shorting out, thats for y’alls help.