In case you were wondering...

[felsmann]

Changing your O2 sensors when needed pays off!! I have 110,000 miles on my truck and I hit a mileadge slump, for the last 5,000 miles I was doing about 14MPG. I decided to change the O2 sensors, since I had to do it at 100K, but did not want to spend the money. They were going to be almost $300 for all three of them at the parts store (Bosch), but I wised up and called our buddies in Atascadero (Fordpartsonline.com) and bought the Ford ones (Bosch) for $180,00 total.

Well, without mentioning that it was a ***** taking the upstream one on the passanger side out (well, I guess I already mentioned it) and that I had to get the hole rethreated, the results have been great!

Immediate gain in power... I did not even know I had lost some over the years. My mileadge now has been great, up to 17 MPG just the other day.

So if you are overdue, don't procrastinate anymore and do it. This is not a performance enhancement. this is just plain old maintenance on your vehicle.

For what I understand, '91-'94 have two, and they go out every 60K, and the '95 up have three (one of them is different, the one after the cat) and they go out at about 100K because they are the heated kind.

Good luck!

 

[Alto]

Tried to do the Same!

Sent my truck in last Monday. Got it out on Wednesday. First of they Insisted I had no 02 Sensors. Then they told me I Had to get a GCC Conversion (Gulf Country @$$@$) something!
Anyhow they said they needed to change my whole exhaust system, change the software on my computer because the US uses Unleaded Fuel and here they don't. Well now they sell Unleaded here only once the Leaded is gone. The dealership insisted it was not true and I needed to convert. Need less to say I didn't but they wanted to charge me 5,500SR ($1,450.00).

Whenever you think they try to hose you. Remember it's worse over here. I did however find a guy who knows what he is doing and after reading your thread will definately change all 3 of mine.
Thanks for the info. Once again this site has saved me money and many heartaches.

 

[Triton46]

Actually, 91 (depending on when it was built, I believe) have one or two. Mine only has one O2 sensor and it is heated.

Got mine for $26 at Advanced Auto. It cured the MPG and a Check Engine.

 

[Jim F]

I could swear that my Chilton manual says my 98 has 4 heated Oxygen Sensors.

 

[felsmann]

Alto, it should be really easy to see if you have any. Just get underneath your car and look for some plug with wires going into your exhaust. If no plugs, then no sensors.

Triton, I doubt that a heated sensor is $26. They are usually about $80 - $100 and they have 4 wires. Chilton's says '90 -'94 are non heated.

JimF you may be right about that. I don't know much after '97s, but a quick crawl underneath your truck should answer the question.

 

[Triton46]

felsmann,

Mine was $26 and has 4 wires....

Anyone know if the 91 has heated sensor?

 

[Robert]

Originally posted by Jim F
I could swear that my Chilton manual says my 98 has 4 heated Oxygen Sensors.

Yes you have 4. You have one on each manifold before the cat and one on each pipe between the cat and the muffler. The OHV 4.0L have a different exhaust setup. They only have one pipe into the muffler which is where their third O2 sensor is installed if they have one. The SOHC has two pipes going into the muffler so it needs an extra O2 sensor for the extra pipe.

 

[Paul Gagnon]

I bought a new oxygen sensor last week. I didn't install it because it was too cold out but I am going to do it this weekend. I hope that it makes a difference.

 

[914x4sport]

heated

well I dont know what you consider to be heated but I just changed the O2 sensor on my 91( as far as I could see there was only one) and it was connected to the exhaust right before where the two headers meet...It was pretty stinkin hot on the exhaust pipe so I'd say its heated and mine only cost about $36 I think its just on the new ones that it gets expensive..Unless your just a sucker and buy from the dealer...

 

[drmoore71]

this is wonderful news! i have been putting this off for ages. my mileae has dropped as low as 11.5 with only minor mods, and i have been dying with gas prices going up. i currently have 112,500 miles on my truck, so i think it is definitely time to go ahead and bite the bullet. thanks for the advice, felsman!!

 

[BoatsRcool]

I changed mine out today. It was $40 and I have a 1992. one of them. The old one I took out was black, so hopefully this will help my milage the new one. I cant see yet, Im putting on my 2 inch lift.

I just replaced my broken FPR (fuel pressure regulator) could that have caused the o2 to go bad?

 

[Triton46]

Yes, thats exactly how it works.

When the FPR goes bad the system runs rich (computer sends more fuel to the engine). This increase of fuel causes more to be burned inefficiently causing an increase in carbon going out the tailpipe. The carbon collects on your O2 sensor until it clogs up and cannot determine the air/carbon distribution.

This in turn sets off your check engine light saying the system is running rich or eventually if it goes long enough (No O2 sensor present).

Since you changed the FPR, you could have kept the O2 (if this has not been going on very long). Since yours was black, I'd say you made the right choice.

I changed my FPR on a 400 mile trip to Pa. I noticed the results immediately on the drive home. Power was about the same but the gas mileage increased from 14mpg to 19mpg.

 

[BoatsRcool]

Ok thanks Triton. I will tell you results of new milage after the lift is completed and alignment.