resistor to bypass catalytic converter

Discussion in 'Import Vehicles' started by ddujon, Sep 27, 2007.

  1. ddujon

    ddujon Newbie

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    HI , I live in the islands where we dont need catalytic converters. I have a resistor that I use to bypass the cat converter on my Toyota Tacoma.I got it from an electronics guy in Virginia. Does anyone know where I can get another one from.thanks.
     
  2. wire

    wire Full Member

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    resistor???

    need more info......what are you calling the resistor......O2sensor????
     
  3. ddujon

    ddujon Newbie

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    HI , Its a resistor that replaces the oxygen sensor (i think), so the cat converter is bypassed. The computer only needs a reading of 50 ohms from the o2 sensor to keep the 'check engine ' light off.So a resistor can replace the o2 sensor to bypass the cat converter.it has worked for me for 4 years... saves me gas too!!!thanks
     
  4. wire

    wire Full Member

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    resistor

    ok.....why then don't you just short the O2 sensor connector with a 50 ohm resistor from radio shack????
     
  5. 2POINTautO

    2POINTautO Hero Member

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    Three sensors, front O2 sensor should not get bypassed nor should it need bypassed, the overheat sensor in the cat can just hang, the rear O2 sensor is probably the one you are bypassing, I am unfamiliar with its location exactly, is it mounted in the cat more to its rear. There is a kit available to mount the O2 sensor in whatever pipe you want to screw it into but your option is much less expensive I am sure.
     
  6. jjm

    jjm Hero Member

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    It would help if we knew the year and engine type.

    This might be the case with pre OBD-II vehicles, but the PCM on OBD-II vehicles typically monitors the response of the rear O2 sensor (sensor 2) in relation to the primary sensor(s) (sensor 1, bank 1 or 2) and it likes to see a slow, gradual change.

    There is no way a fixed resistor will prevent the MIL coming on, the PCM needs to see this varying voltage - by design.

    There are black boxes designed to "mimic" the output of a properly functioning rear O2 sensor (sensor 2), but I find these boxes often prevent OBD-II readiness flags from setting for some reason.

    For years - OBD-I <b>and</b> OBD-II - the catalyst has become a highly integral part of engine subsystems, and removing/bypassing them often causes more harm than good. The engine and its subsystems are specifically calibrated for the backpressure developed by the cat, and removing the cat doesn't allow the primary O2 sensor(s) sufficient gas sampling. The result often is the PCM reading the exhaust stream as "lean" and orders more fuel to the injectors in response. There is no increase in fuel economy or performance unless:

    a) the PCM is re calibrated
    b) the O2 sensor(s) are re calibrated

    Also, keep in mind a number of EGR systems require a certain amount of backpressure to operate correctly, and without the backpressure the EGR will not open. No EGR = burnt valves and perhaps pistons.

    I can't say I'm thrilled about any of this, but cats are a way automotive life - leave them alone and/or replace them if need be.

    Joe

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  7. 2POINTautO

    2POINTautO Hero Member

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    Joe,

    Its a big thing with the younger sports crowd, they want to get rid of the cat and also install a bigger diameter exhaust system to gain what kind of extra horsepower they can get, its all over Japan too, most of them have large black spots on the rear bumper and no one cares about EGR operation either, as a matter of fact, if there is no evidence of an EGR system because 100% of its evidence has been removed too, then it will pass the safety inspection here too, no scanner involved with an inspection, only a CO insp for emissions. Original exhaust usually reinstalled for inspection purposes and it usually has to be borrowed from a friend with a stock car.

    Did any OBD I cars have a sensor 2.
     
  8. csaxon

    csaxon Full Member

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  9. csaxon

    csaxon Full Member

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  10. csaxon

    csaxon Full Member

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  11. csaxon

    csaxon Full Member

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    [​IMG]
    black = heater +
    black = heater -
    white = sensor ground
    blue = sensor signal
     
  12. csaxon

    csaxon Full Member

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  13. dabunk

    dabunk wrench

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    So true, Here in Belize they rip the thermostat out and replace the cat first thing. Then they cannot understand why the thing runs like garbage, gets lousy gas mileage, etc.
     

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