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Oxygen Sensors 99 Silverado 4+

Discussion in 'The Garage' started by 2High4U, Jan 14, 2007.

  1. 2High4U

    2High4U 1/2 ton status

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    I need new oxygen sensor for my truck and there are more than four of them I think these new vehicles SUCK! The cost of one of them are like $80 who else hates being raped.
     
  2. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    o2 sims are cheaper
     
  3. 2High4U

    2High4U 1/2 ton status

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    o2 sims heard of them but didnt think of them... where do I find them and im concerned with gas milage since it is only a 6 banger.

    That would be a very good idea ill look for them and see what kind of info I can find but if anyone else has opinions on them please share.
     
  4. sled_dog

    sled_dog 1 ton status

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    I have never ever seen a vehicle need ALL 4 O2 sensors at once. If there is a code for ALL 4 O2 sensors, don't be looking at replacing them but rather something else.

    Who said you need all 4? Why?

    You can't replace the upstream sensors with simulators. Only the downstreams. The downstream sensors(farther back 2 sensors, past the cat or cats), are there for emissions reasons. They read the exhaust post cat to see whether it is doing its job or not. If you still have the cats, puting in sims will only prevent you from knowing whether you need a cat or not. And if you need a cat it may be clogged and cause other problems. Just food for thought.

    So back to it, why do you need all 4???

    Oh and what is even cheaper than O2 sims are O2 spacers. Go to Autozone, ask for Spark Plug Foulers. Get them in the 18mm size I believe they are. Drill the hole out to approximately 1/2" or so. Make sure the sensor fits through the little hole. Install the spacer into where the sensor bung. Then install the sensor into the spacer. I have done this on 2 vehicles so far. One that had a bad cat(not clogged just not doing anything anymore), and one that had no cats on it. Both of them are OBD-II(the fact that they have downstreams should make that obvious) and pass emissions "legally". I have not tried it on anything newer than 98 however. So a newer computer system may be more sensitive and still realize there is no cat present. Oh the best part, they cost like $4. You can find them in the HELP! section.
     
  5. 2High4U

    2High4U 1/2 ton status

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    Well I dont need all four but I was thinking that it wouldnt be that long until I had to replace the upstream sensors too.

    The downstream sensors are the ones that are bad but I just got into reading and found that there are those four and one on the ex manifold somwhere.

    I have about 100k on the motor and they should be replaced at about this time at least from what I read, im seeing a big decrease in gas milage and the check engine light is annoying.

    I used to get 20-21 MPG now im getting 12-15 like my 99 350 suburban does.
    I dont think the cats are clogged up im not noticing anything different in the motor except that it slightly surges up in the rpm every now and then at idle.

    I just did a tune up... plugs, wires, cap\rotor, rear tranny seal, oil change,tranny filter+fliud, waterpump, refiiled with new expensive dex cool, greased the steerin and driveshafts.

    I dont know.. ill just change the two that are bad i guess, too bad you cant just clean them and reuse them.
     
  6. sled_dog

    sled_dog 1 ton status

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    What code are you getting that tells you, you need 2 O2 sensors? Its strange for both to go bad at once. Truly it is strange for anything more than one to go bad at once. But 2 cats to go bad at once would be even wierder.

    Bad downstream O2 sensors should not reduce gas mileage if they are bad. An 8-10 mpg drop is a MASSIVE change. When did it start, right after the tuneup or after the engine light popped up?

    I didn't see any note of a fuel filter. We recommend them every 15k on Fords, and I say at least the same if not every 10k on Chevy's where they are replaceable.
     
  7. sweetk30

    sweetk30 professional hooker Premium Member

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    also if you have 6cyl then you should only have 3.

    sled dog if you let them go for a bit then thay get slugish and when its to bad then i had to do all 4 at 1 time. :D 100k miles origanal. :bow:
     
  8. 2High4U

    2High4U 1/2 ton status

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    Sweetk30: I have four of them 2 on each side 2 upstream and 2 downstream the only one i didnt confirm was the 4th one that may not be there.

    I was looking at the fuel filter today 100k with the original your right its time ofr a new one hehe. That is the only thing I think I havent done o yeah and the rear end fluid needs changed

    My wife was the one who had the code read at autozone maybe she didnt tell me the full code to determine which one it was.

    I may just go and get it read again to see, I figured that it didnt specify which one hence why I was going to replace both.

    It is definatly one of the downstream sensors.

    Like I said before about replacing them all, I read that they usually go bad at around the 100k mark and figured I would replace them all but because of the cost im not.
    because of your advice Ill just replace the one or both depending on what the code reads.

    Im was just in a rant because of the cost mostly and doing all this stuff to my DD takes away the time I have for my 73 K5.

    Im just hoping that my milage gets better.

    This all started to happen when the light came on by the way.
     
  9. mr.smartass

    mr.smartass 1 ton status Premium Member

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    I would probably change the air filter and fuel filters first... Am I the only one has who hasn't seen realiable results from autozone scanners? Seems like everytime they pull a code it is the O2 sensor... Well most of the time something else is causing the O2 sensor to throw the code... Maybe I'm just paranoid.
     
  10. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Ditto on what sled dog is saying. It's quite rare that both downstream sensors would go bad at the exact same time. Of course, have you considered that the sensors are fine and they are simply doing their job and showing that something else is wrong???

    As mentioned, the downstream sensors should not have anything to do with fuel mileage which makes me think there is something else going on, and I'm also suspicious about hearing about all of the tune-up related work you performed right before this started. A couple of plugged converters could cause the fuel mileage and sensor codes.
     
  11. 2High4U

    2High4U 1/2 ton status

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    I have a K&N Filter that I cleaned for the air filter when I did the tune up, all I should do next is the fuel filter.

    I ran it really hard on the freeway (100MPH) for a good part of the day and the light went off maybe it was one of the cats and they blew whatever was in them out. I got a noticable gain in power and can break the tires loose now.

    I will have to see if the light stays out but im thinking it will.

    The probelm didnt happen right after the tune up but like a month or so after.

    If the cats are the problem and its persistant I was thinking about getting those sim o2's cutting apart the cats and hollow them out weld them back together. I leave that as a last resort.
     
  12. sweetk30

    sweetk30 professional hooker Premium Member

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    sorry i dont agree with the back o2s not affecting milage. thay check to see if the cats are working at spec. and if not thay adjust fuel/air curve to match specs. and this is if all other functions are with in spec for running with in specs.

    so if you have a o2 not reading 100% lets say off to the lean side. it will read and say i am lean i need more fuel or i will bun somthing up. when actualy its fine.

    and yes autozone loves them scaners. but remeber thay ( READ THE CODE AND TELL YOU WHAT IT MEANS ) thay dont run the full test procidures to verify the reason the code poped up in the first place.

    most o2s i replace at work are fine but read real slow and dont cycle at the propor speed to make the computer happy. thats what was wrong with mine in my truck at 100k miles.
     
  13. 6.2Blazer

    6.2Blazer 1/2 ton status

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    I know for sure this is not the case with a lot of vehicles. Besides the fact that the systems are not designed this way (btw, I've been doing diagnostic work on OEM vehicles and working directly with the design engineers from several manufacturers for years) it just doesn't make any sense. You are NOT going to change how the engine is running in order to try to force what the output of the converter is. Converters either work, or they don't. If the downstream O2 sensor has readings outside the set parameter it's either because the converter is failing or there is something wrong with how the engine is running. Only the upstream O2 sensor outputs is used when calculating fuel, ignition, etc....
     

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