Running Rich!

[TrueBlue2002]

My wife has a 2003 Explorer with a 4.6. We were on vacation, and it started running rough and missing now and then, and finally tripped a code. Had it hooked up and the code came back a bad O2 sensor. Replaced the sensor I was told was the problem, but problem still there. I replaced the coil packs, one at a time, drove it after each replacement, problem still there. Cleaned TB, mass-air, and changed spark plugs. Still there. It is putting out a pretty strong odor, and I am now at a loss. Any help would be greatly appreciated. Thank you in advance.

 

[manaen]

Check you fuel pressure, sounds like the FPR is giving too much pressure in the fuel rail.
Have you noticed any black smoke, or soot in the tailpipe?

 

[manaen]

Oh an when you changed the spark plugs what did they look like? where they clean gray, black sooty, or white etc...

 

[TrueBlue2002]

The plugs were a little white, but did not look that bad. The tailpipe has developed a little black "soot" around the outside. I changed out the mass-air sensor last night and my wife says so far it is running perfect. I will check the fuel pressure tonight. Thank you for your help.

 

[manaen]

great, hopefulyl you got it fixed.
BTW.. usually when you get an O2 code it is caused by something else. They do go bad, however more likely then not something is causeing a rich or lean condition and the o2 is the first thing to report it. All the computer can say is that it is giving a rich or lean condition etc.. It really doesn't know why, that's why o2 codes can be difficult to troubleshoot.

The normal culprits are non sensor items like vacuum leaks and fuel pressure, both things the computer cannot monitor (other than with the o2's)