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Discussion Starter · #1 ·
Am thinking about replacing the upstream o2 sensor on my Vulcan to see if it helps my mileage, is that the one i want to replace and how easy it to change?
 

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You have 2 upstream sensors, 1 for each bank. Relatively easy to get to, but you may find them rusted/corroded in, making them a PITA to remove. I will use a Dremmel and cut off the sensor body at the hex and put a socket on it. PB Blaster and heat will also help.

With that said, OBDII closely monitors O2 switching rates, and will kick out a code for a lazy sensor.

Have the sensors been contaminated with antifreeze from a blown HG, leaking intake gaskets, etc? If so, replace them, as they may switch correctly, but have a "chemical shift" in the transfer function whigh will effect gas mileage and drivability.
 

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In theory O2 sensors can last a very long time, but in practice there are so many contaminant that ruin them. The average run they get before the contamination begins degrading their effectiveness is between 80 - 100 miles. It the O2 sensor is replaced as a maintenance item, you are only out the remaining life of the sensors worth of money, which isn't much. If you let them fail and they start to cause problems, they can damage both the catalyst, they can plug up EGR passages, and the carbon build up reduces performance, fuel economy, and can cause physical wear to the engine. O2 sensors also tend to get stuck when they are left in too long. 80,000 miles is a good time to replace them because so long as anti-sieze was used the last time, they usually aren't stuck too bad yet. But wait another 40,000 miles, and they can get completely stuck. My dad's Dakota had the O2 sensor left in there for 150,000 miles, and it could not be removed. Fortunately the exhaust was such that we just cut a new hole and welded a new port on, and installed the new sensor there. You don't want to attempt that on a Taurus.
 

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Am thinking about replacing the upstream o2 sensor on my Vulcan to see if it helps my mileage, is that the one i want to replace and how easy it to change?
Are you getting any codes? have you looked at the sensor output on a scan tool with live data?
 

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Discussion Starter · #5 ·
I have no codes showing as of now was just thinking with the 126k miles on the stock ones it would be something due for a maintenance item, but if its still good i will leave it.

How sure is it that the codes will show when the o2 sens is bad ? Is it possible to have a failing sensor with no code?
 

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Absolutely, probably most O2 sensors start to fail long before a code is set. I strongly recommend replacing it as a maintenance item, see if your economy doesn't improve.
 

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I have no codes showing as of now was just thinking with the 126k miles on the stock ones it would be something due for a maintenance item, but if its still good i will leave it.

How sure is it that the codes will show when the o2 sens is bad ? Is it possible to have a failing sensor with no code?
When the O2's get bad beyond a pre sent threshold, they will trigger a code
and check engine light. Yes they do degrade. but if your having no issues
and mileage is about the same, i would leave it alone. You can check the activity
level on a O2 with a scan tool that does live data and has a graph chart.
Harbor freight sells one for just over $100.

Some of those can be problematic to change. The vulcan top sensors are not terrible
to access, but if there stuck in, they can be a bitch to get out without stripping them
out. When i did mine, i bought a specialty O2 socket that had a pivoting handle to get
leverage at an angle. The firewall side sensor does not allow much room to navigate a
typical O2 socket

The after cat sensors are another issues. The one below your feet on my Gen3, i broke
the top and fought it before i got it out. With it facing straight up against the floor pan,
its virtually impossible to get a good angle and leverage on it.

what ever you do, change them in pairs (before cat pair/after cat pair)
 

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See we are getting conflicting responses here, some posted by those who have never tasted the dark side of what happens when they go wrong. I deal with catalytic converters all the time, and believe you me, most of those that fail are the result of O2 sensors that also failed, but never set codes. The O2 sensors don't set codes until they because almost completely non-responsive. May faulty O2 sensors will output descent response times and signals that are within specs, and yet they are not accurate at all.

The computer does not reject the sensors or even alert you that there might be a problem until you get around 12% off on the Long Term Fuel Trims, yet my experience has taught me that catalyst degradation begins to occur between 3-5%. An O2 sensor costs you between $60 - $80, is not that hard to replace, if its not left in there too long, can improve the gas mileage and performance of the vehicle, and helps protect the catalytic converters from being damaged or plugged.

If the catalytic converter fails, it can cost you up to $800 to have it fixed with aftermarket replacements (depending on vendor and whether or not you have it professionally installed), plus you will still have to get the O2 sensors replaced. Many people have plugged EGR passages and experience EGR problems. I have never had a EGR problem, but then again I also replace my O2 sensors on a regular basis.

Hers how it works. The O2 sensor element gets coated with deposits, which can be sulphur compounds, chemicals from the oil, carbon, antifreeze, etc. These deposits reduce the sensors active surface area, which causes a decrease in the voltage output. The computer cannot tell the difference between the low voltage from a contaminated sensor and a lean condition. So the computer will increase the injector pulse width to compensate, which will produce the desired effects. The lower oxygen level will cause the voltage to increase even if the sensor is contaminated. However this rich condition will begin to cause additional deposits to form, which has the same effect on the catalyst, the sensors, and it causes carbon deposits in the combustion chamber, EGR passages, etc. All of this begins to take its toll.

If you want to wait until the sensor sets a code, its your car, but some of the damage that is done cannot be reversed. Using an injector cleaner or a product like Seafoam does not restore catalyst function, nor does it undo scuffing and scarring to the cylinder walls due to carbon deposits around the rings.

The computers parameters for acceptable O2 sensors in my opinion are way too lenient. The computer should begin warning you of problems at around 6%, not 12%. In my opinion, paying $60 to $80 for a new sensor is cheap for having a nice car that will be reliable and trouble free for years, as opposed to leaving it in there and having to spend major money fixing failed emission components or having to get another car simply because the old one has become too costly to repair. An once of prevention is worth a pound of cure.
 

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See we are getting conflicting responses here, some posted by those who have never tasted the dark side of what happens when they go wrong. I deal with catalytic converters all the time, and believe you me, most of those that fail are the result of O2 sensors that also failed, but never set codes. The O2 sensors don't set codes until they because almost completely non-responsive. May faulty O2 sensors will output descent response times and signals that are within specs, and yet they are not accurate at all.

The computer does not reject the sensors or even alert you that there might be a problem until you get around 12% off on the Long Term Fuel Trims, yet my experience has taught me that catalyst degradation begins to occur between 3-5%. An O2 sensor costs you between $60 - $80, is not that hard to replace, if its not left in there too long, can improve the gas mileage and performance of the vehicle, and helps protect the catalytic converters from being damaged or plugged.

If the catalytic converter fails, it can cost you up to $800 to have it fixed with aftermarket replacements (depending on vendor and whether or not you have it professionally installed), plus you will still have to get the O2 sensors replaced. Many people have plugged EGR passages and experience EGR problems. I have never had a EGR problem, but then again I also replace my O2 sensors on a regular basis.

Hers how it works. The O2 sensor element gets coated with deposits, which can be sulphur compounds, chemicals from the oil, carbon, antifreeze, etc. These deposits reduce the sensors active surface area, which causes a decrease in the voltage output. The computer cannot tell the difference between the low voltage from a contaminated sensor and a lean condition. So the computer will increase the injector pulse width to compensate, which will produce the desired effects. The lower oxygen level will cause the voltage to increase even if the sensor is contaminated. However this rich condition will begin to cause additional deposits to form, which has the same effect on the catalyst, the sensors, and it causes carbon deposits in the combustion chamber, EGR passages, etc. All of this begins to take its toll.

If you want to wait until the sensor sets a code, its your car, but some of the damage that is done cannot be reversed. Using an injector cleaner or a product like Seafoam does not restore catalyst function, nor does it undo scuffing and scarring to the cylinder walls due to carbon deposits around the rings.

The computers parameters for acceptable O2 sensors in my opinion are way too lenient. The computer should begin warning you of problems at around 6%, not 12%. In my opinion, paying $60 to $80 for a new sensor is cheap for having a nice car that will be reliable and trouble free for years, as opposed to leaving it in there and having to spend major money fixing failed emission components or having to get another car simply because the old one has become too costly to repair. An once of prevention is worth a pound of cure.
Conflicting opinions are relative to the situation. You get a 10 year old+ car with over 100K, most people are not going to put unnecessary money into the car if they can help it. Even most of the auto thieves at the quick lube shops and such don't normally try to sell you O2 sensors unless the code light is on. Sure i will agree, the sensors do degrade. So does EVERY other system on the car. So a car with
100K+, where do you want to start replacing things? If O2 sensors cost what spark plugs do, it might be a little different deal. But to
replace 200+ dollars of parts on a car that's running OK, a lot of people are going to have a hard time cost justifying it.

You also mentioned them getting stuck. Thats a VERY real issue. i have experienced it myself more than once. You break one off trying to
save a few bucks on a otherwise good running car you have shot yourself in the foot.

If you have an older car in pristeen shape and are going to keep it forever, well, spend what makes you feel good on maintenance. I spend what i have to to keep it running resonable and safe until its no longer economical to do so. I could probabaly go out today and spend a $1000 on various systems of my 97 if i spared no expense. But that's not on the crystal ball in the near future. A front wheel bearing might be though.

I just wish i had smarter scan tools to help me diagnose things at times.
 

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So if the car has little or no rust, it is good for another 200,000 miles. Most cars made after 1990 except GM and Hyundais are capable of reaching 300,000 miles cost effectively if the car is properly cared for.

So I fail to see your logic, you spend a couple hundred to fix a car that can still be a good car for a long while, or you wait till other things go wrong, forcing you to shell out hundreds more or even thousands to fix parts that never would have failed otherwise, or forcing you to get another car, also another expense which can cost as much or more than fixing the old one.

The reason quick lube shops and stuff don't sell O2 sensors is one, they are not familair with that kind of work, they only sell work that is quick and easy for them. I've even seen shops spot leaking water pumps and not mention it to the customer because they didn't want to be bothered with a job that involved.

I've found the recipe I use has worked good for me. I have run one vehicle past 500,000 miles, and it repaid me many times over, despite the fact that the truck began to become a money hole towards the very end. Over its 500,000 mile life, it maybe cost $20,000 including its original $7,000 price tag. 500,000 / 20,000 is a mere $.04 per mile. My Aerostar has cost me about $12,000 so far over 130,000 miles (two trans rebuilds in there) which is still a mere $.09 per mile. Some of those expenses were also in the form of upgrades to make it more load capable. My Taurus to date has cost me about $.07 per mile. Fuel expenses are a separate story, my van costs about $.19 per mile, and the Taurus runs about $.14 per mile.

My point is, neither of my current cars are junkers, they are both nice cars. I don't care what people say about resale value, I have no intention of selling them till I am done with them. If you think about repairs in terms of cost per mile, it is generally much better to run a old car for longer than to keep buying new. If I replace them with the same kind of car, I also get to reuse parts and upgrades, allowing me to apply my investment in one towards the next in the event the car gets totaled. Since my cars are older, my insurance is cheaper.

By replacing the O2 sensors, you are staving off other more expensive parts that could cost you later.

Now if you don't care about having a nice car, and you just intend to keep buying other used junkers, then by all means, fix no more than absolutely needed.
 

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What ever works for you, works for you. But cars wear out. You keep a car long
enough you see parts degrade and fail that you don't normally see.

I live in the rust belt. If they don't wear out, they rust out. I had an old Mazda B2000
i drove the wheels off of. I loved that truck. BUT, it was burning oil and i had to change or clean the spark plugs on a regular basis. I think it was just valve seals,
but on a old truck thats major work. The box was so rusted the sides literally
flapped in the breeze. It was still running, but it was time to go. Got $500 from some
Mexican who drove it to Mexico.

Taurus history:
89 wagon: totaled by wife
90 sedan, some rust, squeaking in the rear, Sold running for fair amount to get another car (got a deal on a gen2)
93 sedan totaled by wife (see a trend here?)
93 wagon 260K, needed about everything, hit on four corners, drove it to
junkyard with failing head gasket.

97 sedan. bought with bad Vulcan. current daily driver
98 sedan, bought with 180K needed water pump. wife's car. a lot of wear items
replaced on that one.

When you keep a car long enough, strange things fail.
on the 98 sedan i have, the trunk would not stay up when open
First time i saw that one. Hood would not either. (fairly common).
I had a few donors and pieced some of the parts back into the wife's
car.

Your in a harsh climate and things like bushings and sub frame mounts go.
then struts and springs. And with a Taurus trannie, your on life support over 200K
(my wagons trannie made it 260K, but i would not call that normal)


Parts wear out. Its a fact. you either replace everything you find and spend a lot
of money, or let some things degrade and sell the car while its still running and not
economical to repair.

You can ask some folks here with gen1/2 3.8's how many got over 200K with no
trannie or head gasket failures, or how many junked the car because of those issues.

Now, i don't know what all your driving, but were talking about TAURUS here.
not anything else for this discussion.

i drive my cars and use them up. And when its time, i move on and get what i can
out of them wrecked or running.

I really don't understand your snipe about buying junkers. I bought a pristine 97
with AX4N and remote key entry with a bad motor for cheap. and put a motor in it.
That car was well worth saving. I could not have bought a car like that for what i
had in it at the time. One guys junk is another guys project. The car has taken a few
setbacks since i did the motor, but i intend to drive it for a few more years until a better project comes up cheap that's newer.

Its not hard to find good tauri with bad motors or trannies for cheap. If you have the
resources to do it your self, why not? Fix it. drive it for awhile. get your money out of it and move on to next project.
 
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