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Attention TBI guys, anyone running heated O2 sensors?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BayouBlazer88, Dec 31, 2003.

  1. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    I have been reading up a lot lately on the cfm-tech.com website about different tbi tune-ups and ran across an article that said the 3-wire (heated) O2 sensors work much better than the old 1-wire sensors especially with headers (which is my case). Said they run much better when cold and generally better overall. Anybody tried this setup? Does it work pretty good? My 88' 355tbi with vortec heads runs downright horrible when cold and hopefully this will help with the problem. Also thinking about getting one of their tbi spacers and bored out throttle bodies but thats another story. Thanks in advance for the replies.
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I'm interested to the answer to this question because I've wondered the same thing.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    I don't think the heated O2 sensors are any more "technologically advanced" than the non-heated ones. Both operate in an extremely narrow voltage band, they basically only go over or under 14.7:1 ratio, meaning rich or lean...the voltage on either side of that ratio is nowhere near what it is at 14.7:1.


    Aw heck, a picture works better O2 sensor graph

    Wide band O2 sensors are more "precise", but they are much more expensive.

    As I said in another post, if you think the O2 sensor is the problem, you need to get a scanner on it. (or maybe winALDL) If you see it dropping out of cold loop while the engine isn't working hard (stopped in traffic for instance) then you know the O2 sensor is getting cold, or is bad.
     
  4. Bushwhacker

    Bushwhacker 1/2 ton status GMOTM Winner

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    When I did my TBI swap I put a heated O2 sensor in my header. I have had no trouble. Cold startup and drivability is fine. /forums/images/graemlins/wink.gif

    Clay
     
  5. BurbinOR

    BurbinOR 3/4 ton status

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    All a three wire O2 sensor does differently than a stock one wire is get the motor into closed loop sooner, hence allowing the motor to be managed more precisely.

    Easy to do, worth doing. /forums/images/graemlins/smile.gif
     
  6. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    where is a good place to connect the heater wire for the O2 sensor? I was thinking of just connecting it at the radio fuse, would that be ok? And how bout the ground? I was gonna connect it to the frame around the headers. thanks.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Plenty of ignition accesory ports in the fuse panel. Don't splice into other wires. You can cut the leads off of just about any 80's GM product, (and later, Astro's are great donors) just get the right "keyed" connector.
     
  8. K05Aggie

    K05Aggie 1/2 ton status

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    I run a three-wire O2 with headers. I didn't notice a difference when I switched over and I ocasionally pull the lead out of the heater - A/C fuse, but I don't know until I look. So it works, but no better for me than a one-wire. And as dyeager and BurbinOR said, the only difference is the heater.
     
  9. K5 NUTT

    K5 NUTT 1/2 ton status

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    What Frank said....

    DW
     
  10. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    well in that case, cfm-tech.com sucked me in. Already bought one in the sense that I'm open to just about anything that will make this thing run correctly. And their logic behind the heated sensor seemed to make a lot of sense. Oh well, might as well throw it on. I'll install it tomorrow and let you know if I notice a difference.
     
  11. beater_k20

    beater_k20 Banned

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    i had an intermittent SES light when i eliminated the cat on my 93 C1500. i had several shops look at it, and they all pretty much said that it was due to not having a cat, and an improper ammount of backpressure not allowing the o2 sensor to get into its proper heat range to work. i was told that a heated o2 sensor would cure this. i never did anything about it, and my truck never ran badly.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, in a couple of senses, they do work better. Your engine can go into closed loop quicker essentially, and if it does get too cool in its current location, a heated one can solve the problem.

    They won't hurt anything, but if the extra heat isn't necessary, won't help either.

    I'm going to try a "stock" unheated O2 in the reducer (? exhaust pipe side of header) which is a long ways away from stock. If it doesn't work right, heated all the way.
     
  13. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    CustomEFI's had me install a heated O2 in the 454, it was located in the header collector as well. An oxygen sensor produces no voltage when the sensor temperature is below 600 degrees F. Until the sensor reaches operating temperature, the engine computer operates in open loop mode where default fuel settings are used.

    Thats all there is to the heated O2. If your O2 never gets to temp, or cycles back and forth around the 600*F mark, it could cause strange problems.

    Just my .02!

    -Dan
     
  14. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    CustomEFI's had me install a heated O2 in the 454, it was located in the header collector as well. An oxygen sensor produces no voltage when the sensor temperature is below 600 degrees F. Until the sensor reaches operating temperature, the engine computer operates in open loop mode where default fuel settings are used.

    Thats all there is to the heated O2. If your O2 never gets to temp, or cycles back and forth around the 600*F mark, it could cause strange problems.

    Just my .02!

    -Dan
     
  15. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    CustomEFI's had me install a heated O2 in the 454, it was located in the header collector as well. An oxygen sensor produces no voltage when the sensor temperature is below 600 degrees F. Until the sensor reaches operating temperature, the engine computer operates in open loop mode where default fuel settings are used.

    Thats all there is to the heated O2. If your O2 never gets to temp, or cycles back and forth around the 600*F mark, it could cause strange problems.

    Just my .02!

    -Dan
     
  16. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Seen plenty of double posts, but a triple post? /forums/images/graemlins/rotfl.gif
     
  17. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    [ QUOTE ]
    Plenty of ignition accesory ports in the fuse panel.

    [/ QUOTE ]

    -there are? what are they labeled and how do I connect a wire in there? Do I just connect a wire to the end of a fuse and plug it in? Do I need to use a certain kind of connector? thanks.
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

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    The accessory terminals on your truck will be above all the other fuses. No, you don't tap into existing fuses, you get the right plug (auto parts stores MIGHT carry them, wrecking yards are full of them) for the terminal you need (such as ignition only hot) and solder whatever lead you have, to that plugs wire.

    The ports above the fuses are "grouped" together, some are 12V constant, some ignition hot, one dimmed via headlight, and maybe one more set. Probe them with a voltmeter when you have the key in the "run" position, and with it turned off.

    The accessory ports are also "keyed". When you look closely, the blade setup will all be the same, but there will be an additional piece of plastic cast into each plug, which allows it to fit into only one group of ports. (Again, 12V constant, etc.)

    If all the ports are taken up (some of the later trucks had a LOT of accessories plugged in here) GM also made "piggyback" adapters, which allowed multiple taps into the same accessory terminal.

    I believe there are 4 ignition hot only ports, starting from the top right of the fuse panel as installed, they start 3 or 4 spots to the left, then go down two or three more spots, then right one or two more spots. Again, probe them with a multimeter and it will be clear which is which.
     
  19. fortcollinsram

    fortcollinsram 1/2 ton status

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    Well my 454 kind runs like crap when it is COLD and there are sustained periods of off-throttle deceleration...I am going to be putting in a 4-wire o2 as soon as I get back to Colorado. It has 2 extra wires for the heater and also has a separate ground wire for the signal for a more accurate signal to the ECM, On my engine with the Thorley headers, the O2 sensor is damn near as far back as the transfer case and in the factory mannifold, it was only like 11 inches from the exhaust ports...So I hope that the Heated O2 will fix some of my problems.. I am also going ot be adding a vacuum referenced fuel pressure regulator to keep fuel pressure at an acceptable level at idle but a bit higher at WOT. Right now I am having to make a compromise b/w a stoichiometric level at idle and lean at WOT or rich at idle and stoich at WOT.
     
  20. k5moneypit

    k5moneypit Registered Member

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    I have a 350 tbi with headers, the o2 sensor is at the collector, i've never had any problems with it, although it is a two wire type. I would relocate it to the collector, that should do the trick. /forums/images/graemlins/k5.gif
     

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