first time poster here, I have a 98 f150 2wd reg cab short wheel base. it has the 4.2 v6 with 5 speed manual behind it. i cant seem to figure out why it's running so darn rich! at idle it has black smoke coming out the exhaust and when i rev it up i can get big black clouds. i replaced all oxygen sensors and put new spark plugs in it and no change. scanned computer to find codes for oxygen sensors (all 4) i erase them but within a day or 2 the codes come back (even though all 4 are brand new) really stumped here and tired of throwing money away. Fuel mileage is HORRIBLE!!! got better mileage with my 2002 4x4 4.2 long box. any suggestions would be greatly appreciated

 

I don't know anything about a 4.2, but if it's got a fuel pressure regulator I'd check that. Could possibly be sticking injectors I guess.

 

Which exact codes, please?

 

When they come up again I'll post them on here

 

P0133
P0135
P0141
P0153
P0155
P0161
P1132
P1152

These are all the codes that come back after 1/2 hour to an hour of driving after I erase them.

 

A look at all the codes discriptions are telling you there is a harness issue connecting the OX sensors to the computer.
Without feedback from the Ox sensors the motor is run on rich fixed fuel tables in the computer program, so the situation does not completely disable the motor. Courtesy of the engineer's concern for the driver.
Check out the harness from the computer area back to the sensors for being grounded, crossed or open.
You must pay attention to the codes, nothing else, and no guessing.
Good luck.

 

thank a lot! put the scanner on and checked live data and I have no info from rear 2 sensors. front 2 seem to be functioning fine. any idea if each sensor has it's own set of wires from computer or do they share positive and ground feeds?

 

Bare with me now because I'm not trying to belittle you but for you to learn.
Posting that the front sensors are fine does not reassure me you know what the correct front and rear actions are.
This is born out by asking if the rear sensors share any circuits.
They do not.
Sensors are monitored individually on separate leads to the PCM.
The sensor heaters are also monitored separately.
You have a list of codes proving the PCM monitors them separately with the code descriptions telling you which ones they are..
To review; you have heater codes. A fault with the harness, a cable plug or maybe the sensor heaters themselves.
Why; the PCM monitors the current drawn by each so knows when the current is either absent, to much or to little within certain limits.
The sensor outputs are also monitored for switching ratios and timing.
To repeat, if the Ox sensors are not outputting properly the motor will run rich by program design.
.
The rear sensors will not switch 'like the fronts' because that is not their job at that position in the cat pipes. Hence they may look like they are not working.
We need some numbers on these sensors to tell anything about what is or is not going on.
I would advise again to check over the harness under the truck for rub through grounds, crosses and breaks.
The codes suggest this is an issue because there are to many sensor operations in trouble at the same time in the same area.
Good luck..