Bad oxygen sensors?

Yes faulty oxygen sensors will definitely hurt your MPG. faulty oxygen sensors can also lead to destroying the catalytic converter here is a guide to help change them with instructions below to show you how on your car.

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

Check out the diagrams (Below). Please let us know what happens.

First of all why are you replacing them? Any codes?

Well you already have the o2 sensor right. Id bring it to a local independant repair shop. I dont care how stripped it is I can replace any o2 sensor in an hour. We(independant repair shops) deal with broken stripped stuff all the time. Youd be surprised how fast it can be fixed by a mechanic thats done it a hundred times already. Give it a shot. Tell them up front you dont want to pay more than an hour labor. Your garage should do it. If they dont go to the next one, someone will want your business, trust me. Let us know how you make out.

Codes P0171 and P0174? Fuel pressure checked? Checked for vacuum leaks? Exhaust leaks?

Lean fuel condition could be caused by one of the following below:

1. Vacuum leaks
2. EGR and PCV valve.
3. Low fuel pressure.
4. Dirty fuel injectors.
5. Mass Air Flow Sensor.
6. Oxygen Sensor.

Check engine light on? When you say you welded the O2, do you mean you actually welded the O2 itself, or the new thread hole? If you welded an O2, you may have destroyed it. Welding heat is higher than the operating range of the sensor, and it probably burned the O2 heating element. I would replace ALL O2 sensors with the mileage on your truck. Also if the original position of the sensor was in the cat, put it back there. It's designed to sense oxygen at that point!

Your check engine light should be on and P0420 code should be set. There is NO PCM reflash for converter removal that I know of. Your ONLY solution is to put a good cat back on it.

Merlin2021,

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I did a lot of experimenting with O2s, when I installed one in my exhaust, just where the Hedder dumps in.

I did quite a bit of checking when I was doing this (You were my very 1st answerer here at this site) Isn't that special!!!!........My question was about using a O2 sensor to Select the correct JETS, my 4 Barrel Holley Carburetor........almost 2 years ago.

I used both a DIGITAL Voltmeter, set on Millivolts, and also the AIR/ FUEL METER, it uses LED lights RED (lean) Yellow (stoich [close 14.7:1 perfect burn] ) and Green (rich)

Both methods are good for me, voltmeter is more accurate, but hard to keep up with........The lights really show whats going on with the O2 sensor if you are driving alone.

This method sorta sounds stupid for a Carburated CJ 5 JEEP........But after I finally figured out the factor that was throwing me off with JET CHANGING (wrong PCV for the way my engine was configured) , The Darn Jetting got EZ and I was able to Tune my Carb, to make it as efficient as it could be, with the way I drive.

Now, When things were screwy, I put different ones into a COMPUTER CONTROLLED CAR, just to see what both my Voltmeter and the A/F gauge would do. You simply just Jumper wire into the sender connection, lets the computer still use the info, and you can read it too.

Just like they said, The Computer keeps the Vmeter at about 450 MV and the Add On A/F Meter in the middle of the yellow light band (as it constantly adjusts for too rich and too lean) Does this really fast!...........Carb cannot keep up or rather hold this Efficient burn!....But it will help you get the carb right, a lot EZer than "PLUG CUTS", or keeping up with MPG all the time.

Moral of my NOVEL

If you hook up a Air/Fuel Meter or Voltmeter to the EXISTING O2......see what its doing...........Then swap to a new oneNot designed for the CAT! (they come heated and unheated) Try to find an inexpensive one that Connects in the same to your wires, and try it, see if starts showing about 450MV or yellow lights

A small Ma and Pop self service auto salvage yard might yield some really cheap TEST DUMMIES---Insure you write down vehicle info for each (yr, engine, make) so that if you find a winner----you can get a new one for THAT particular application.

I know the other sensors and O2s come into play with all of this, but what should the MV Output be on the CAT O2 if it were straight out of the FORD assembly line?

OK, I shut up now, I am an IDIOT, I am a Plumber with Jeeps.........Scold me now, Merlin2021

The Medic

My Air/Fuel Meter is on my column, beside the tach.

Your old Jeep dosent have the same type PCM as a 96 Ford, any model. It constantly tries to achieve a 14.7-1 air fuel ratio, controlled by the PCM. An unheated O2 will not perform in these vehicles. Soon ALL states that get federal money for highway projects will require the vehicle to have the same exhaust configuration the car was built with. NO acceptions. Also NO carb on this truck Fuel injected, and his PCM cannot get the A?F right, because the sensor data is wrong. It is trying to enrich the fuel to cause the cat to heat up, his PCM is stuck in warm up mode. (RICH). CJMEDEVAC, I don't mind help if I ask for it, but I don't like Monkey wrenches thrown in my direction. If your advice is followed, will you buy the new PCM for this Ford?

Well first of all your truck will hardly run properly if you manage to get it started. Next you will have too lean of fuel resulting in a lack of power and acceleration, or you will have too rich of a fuel mixture causing excessive gas burning. Either one will wear out your engine over time.

If you have an exhaust restriction, that could definitely be your issue.