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Thread: 3 wire o2 sensors

  1. #1
    Fuel Injected!
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    3 wire o2 sensors

    high, was going to wire up a 3 wire o2 sensor in my truck, it has a 1 wire. what I was wondering does the 3 wire [94 model chevy pcm cut the power to the o2 sensor after it gets heated up or does it continue to supply 12 volts to the sensor.] my truck is a 91,my sensor is getting lazy and I found a 3 wire fore about the same price as a 1 wire. hope everones doing ok been busy.

  2. #2
    Super Moderator Six_Shooter's Avatar
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    The 3 wire sensors have 12 while the ignition is on. There is no heater control, unlike a WBO2.
    The man who says something is impossible, is usually interrupted by the man doing it.

  3. #3
    Fuel Injected!
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    thanks six shooter, ill order it here in a little while. I figured I will put a relay to the heat wires its a pretty good price if the sensors are good 22.50 shipped.

  4. #4
    RIP EagleMark's Avatar
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    Plus a relay and wiring... don't forget a new plug/pigtail to plug into the heated sensor. Pretty easy to find a pink wire from the EFI system to tap into and trigger relay on at Key On.

    All that stuff is like $5 at JY when you pull it from trucks and cars.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  5. #5
    Fuel Injected!
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    I think why it goes open loop like in town or the gravel road I live on is the differentce in the fuel iam getting. I will proble get my order Tuesday then I can play if I get time to .still getting 19-21 mpg but you can tell something is not just right at polk alone speed.

  6. #6
    RIP EagleMark's Avatar
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    Could be cooling off?

    Or is the bin set for OL idle? Look at RPM settings in "Open Loop - RPM Threshold" compare to ADSU which is CL idle.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  7. #7
    Fuel Injected!
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    I think that is what it is doing[cooling off] I don't have a cat on it. I checked the bins its closed loop idle, if I keep the rpms up a little higher it stays closed loop, I like polking around 20-30 in 4th gear on these roads I doubt gm made acomadations for that

  8. #8
    Fuel Injected!
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    put that3 wire o2 in it sure smoothed out my polk along driving speed in town on dirt an gravel it even helped at cold start up if I had a cat with balls in it the 1 wire probly wouldn't have cooled off so quick. miner 6 year drivability problem solved.

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