just wondering if i should replace any or all of my O2 sensors at 143k miles on my 5.4. will it run any smoother by changing them possibly? considering cleaning the throttle body as well.

 

we got about the same miles on our units....I to was questioning this.
I went ahead and did change the front (2) O2 sensors. Now, I wasn't experiencing any CELs or rough running, mine ran pretty well prior to changing them...I did it as a maintenance . It did help smooth it out, maybe a bit and maybe a bit of economy came with it as well...gains were minimal at best. The running better and mpgs didn't show up immediately though, it took some drive cycles, & it did seem to get to operating temp a couple of miles sooner. Now, did I jump the gun, perhaps??...I did have piece of mind that this was done & that I was doing everything that I could to keep it in prime running condition, which the best here and other forums will tell you that is paramount to getting longevity out of these and any other vehicle.

hope that helps...maybe not it really boils down to your situation and dollars spent vs amount of gain.

 

The front o2's should be replaced about every 100k or so. The rears should only be replaced if they fail.

 

Yep, that's just good maintenance. I'd change the rears as well. All four at the same time.

 

I just changed my front ones, seems a little smoother. Not sure on mileage yet

I would just change the front ones, the rears just tell the computer if your cats work or not

 

For the rear sensors, peak and low voltages are also continuously monitored, but if the monitor has not detected a peak or low voltage beyond threshold, then the fuel/air mixture is forced high or low in order to get the sensors to start switching. Slow switching has an effect as they work together to some degree. If your really shooting for the best outcome, change all 4 at once and @ 100,000 miles.

 

NOTE: The Rear O2's often seize inside the bungs. Forcing them out isn't a good idea unless your okay with the possibility that you may have to remove the crossover section of the Y in order to repair the bungs.

When they are forced out, they usually either take the threads with them or screw them up badly. You can run the engine just before removal to assist in corrosion breakdown, but that usually does not provide the heat needed once they're fused together.

If you could heat them up with a torch under the truck, it wouldn't be a big deal, but that's next to impossible given their position.

So, -if you can get them out,- fine. IF they start binding on yuh, -think twice lol.
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The Forward O2's aren't usually a problem.

 

thanks jbrew. i mean i had my high flow cats installed like 2 years ago and they had them out then so hopefully they wont be too bad. i will replace all 4. would advance or like napa have the bosch sensors?

 

You can order Bosch or Motorcraft sensors from rockauto.com.

 

ORiely's has them here. Napa's is good tho, they should have them, but you never know for sure. Not all related third party parts suppliers stock exactly the same thing, so you have to check. Bosch or Motorcraft only. I've ran BW's before and mileage went down to 9 mpg. OEM's are louvered and spin exhaust around the sensor for accurate AF's. Knock-offs and others just have a a few holes and the sensor gets blasted, - less accurate IMO.

 

Ive read bosch and Motorcraft are the same. Bosch is said to supply OEM Motorcraft.. You can get Motorcraft at Rock auto for 5 more bucks then the bosch so if I were ordering them right now I'd get the Motorcraft ones at Rock auto. I got mine at Autozone 5 years ago I got Bosch and have had no obvious issues seems like they were nearly 50 bucks at autozone clear back then..

 

Actually their not the same, Ford used both at the factory tho. Bosch is more common.

Although Justin isn't entirely correct, since the manufacturer installs Bosch @ the factory, - I assume his graph has some weight.

This one -

http://www.vmptuning.com/forum/showthread.php?t=825

 

Who knows. Like I said I read that-dont make it true. I would get the motor craft ones at Rock Auto if I were replacing them right now. bosch are about 30 bucks and motorcraft are about 35. Might as well get the motorcraft at that rate. Not worth screwing around with anything else.

 

I know lol. Yea I would do the same. Just checked ORiely's and they want $68.99 Each , - per Motocraft sensor.

 

thanks for the help guys