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should my 1985 305 cid have an Oxygen sensor?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zach78k5, Oct 13, 2004.

  1. zach78k5

    zach78k5 1/2 ton status

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    I dont have the truck near me now but will a 1985 have an o2 sensor? If so I would assume it is located on my header somewhere.
     
  2. js4x4

    js4x4 1/2 ton status

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    look on the drivers side exhaust manifold, near where it mates up to the pipe....I have an 87 TBI engine, so not quite the same I know....
     
  3. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    my dads 85 k5 blazer didn't have one. i guess the cali emisions(sp) could have one /forums/images/graemlins/dunno.gif
     
  4. k20

    k20 3/4 ton status

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    no, because it isnt fuel injected, it would be pointless to have an O2 sensor, because the carb cant adjust to whatever the O2 is reading.
     
  5. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    It will for surely have one if it is equipped with the california standard emmissions equipment. It will have the wonderfull computer controlled carb and distributer setup.
     
  6. mahorney

    mahorney Registered Member

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    It don't believe it does. I took some parts off a stock 85 truck with 305 that didn't have one. I bought a set of edelbrock emmissions legal headers and they have the oxygen sensor port on the driver's side. Had to plug hole.
     
  7. BlackDog714

    BlackDog714 1/2 ton status

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    My 85 had the "High Altitude Emissions" package with a knock sensor, but no O2 sensor.
     
  8. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    [ QUOTE ]
    It will for surely have one if it is equipped with the california standard emmissions equipment. It will have the wonderfull computer controlled carb and distributer setup.

    [/ QUOTE ]

    Correct, if it has a feedback carb, it has an O2S!
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    As was stated, with a feedback carb (CCC system) it WILL have an O2 sensor. Apparently not a knock sensor. This apparently applies ONLY to certain models destined for CA originally.
     
  10. R72K5

    R72K5 Banned

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    80-up is when the system existed, most of them all had O2 and MAP sensors, etc, this system was used on lighter max load(GVWR) rated cars and trucks under 8000 or 8001 lbs,

    heavier max load rated vehicles had a TCS system, a metal relay deal on driver side valve cover, this was for heavier GVW vehicles, mostly with 4 speed but not limited to that
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    Not quite. CA only emissions trucks were either CCC, or not. CCC uses both O2 and MAP, no exceptions. If it doesn't have those, it doesn't have a "feedback" carb, and is not CCC.

    One interesting difference between CCC cars and trucks is that *apparently* the trucks didn't use a knock sensor in all CCC setups (or perhaps any) along with Oldsmobile engines which also didn't use a knock sensor until about 1987, while all Chevy car applications did.

    CCC was used on ALL carbed GM *cars* starting in 1981 and ending in 1990. Started in 1980 IIRC only on Cadillacs, at best a VERY limited number of vehicles, not 100% as in 1981.
     
  12. J.R.

    J.R. Guest

    mine had the knock sensor but no O2...
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Then it's ESC, not CCC.
     

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