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02 sensor tech question?

Discussion in 'The Garage' started by Thunder, Jan 19, 2003.

  1. Thunder

    Thunder 3/4 ton status

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    Just got done putting on a Flowmaster Exhaust on my buddies 91 K2500. We also took off the cat.
    When we were done we took it for a drive. My buddy liked the way it ran and better performance. But i thought it should have had better throttle responce. So I checked the timing and put a scanner on it.
    When checking the O2 sensor out I kept getting "02 sensor not ready" and the computer kept staying in "Open Loop" mode and would not close the loop to operate off the 02 sensor.
    The truck was at operating temp (195 degrees)
    The 02 was putting out 400- 500mv
    02 cross counts seemed about right.

    Think the 02 is bad? I put in a new 02 a year ago and the truck doesn't get many miles put on it.
    Or by removing the Cat maby the 02 sensor is not heating up enough to start working. /forums/images/graemlins/confused.gif
    The 02 is located on the exhaust pipe down stream from the Y about a foot in front of where the Cat used to be.
    Any thoughts on this is appreciated.
     
  2. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color="blue">When I first did my TPI swap, I put the O2 in the collector. If I was idling for extended periods of time it would go into open loop. I now run 88-98 shorty headers which put the O2 a lot closer to the exhaust ports and it doesnt do it anymore. Sounds like you need to move yours upstream of the exhaust a little

    Or just convert to heated O2 /forums/images/graemlins/tongue.gif
     
  3. Thunder

    Thunder 3/4 ton status

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    Hmmm I guess I'll have to talk my buddy into getting a set of headers. /forums/images/graemlins/laugh.gif
    Just wondering..... When you switch to a heated 02 do you pick up switched 12v off the fuse panel or is there a better source?
     
  4. jc71355

    jc71355 1/2 ton status

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    I was told to do it off the Fuel Pump.
     
  5. ZonkRat

    ZonkRat 1/2 ton status

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    Got rid of cat on my 88.Did full duals with flat turbos at same time.Didn't have O2 probs,but mines in the drivers side manifold. /forums/images/graemlins/crazy.gif /forums/images/graemlins/truck.gifer in TENN. /forums/images/graemlins/thumb.gif
     
  6. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color="blue">Any ignition source will work, most go off the fuel pump. I will probably splice it into the low side of my fan relays to make it neater (I'm a neat freak when it comes to wiring /forums/images/graemlins/crazy.gif)
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Just be prepared when you go to the store to buy the heated O2 sensor. The one for our '94 Sub cost $60. /forums/images/graemlins/shocked.gif
     
  8. Chris Demartini

    Chris Demartini 1/2 ton status

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