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Thread: Options for Eliminating Downstream O2 Sensors

  1. #1
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    Options for Eliminating Downstream O2 Sensors

    New to the forum. Have a Chev 2016 LT / 8L90 installed in a 2008 JK Jeep Wrangler with a Motech of Las Vegas install kit. First start is very soon. I want to disable the downstream O2 sensors and not install CATs. Should I keep the sensors around in order to keep closed loop tune and simply install the downstream sensors with the back out bungs welded in the pipe about 12" downstream of the upstream sensors or simply disable the downstream sensors in the ECU and get rid of closed loop tune? What is my best option as I want the HP and economy that this engine is going to give. I live in Canada so can get away with the delete of CATs.
    Last edited by JKLTGuy; 1 Week Ago at 09:18 PM.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Closed loop has nothing to do with the rear o2 sensors. The rear sensors are there to monitor the cats and not tell the computer to run in open or closed loop. Only the front o2 sensors are used for fuel trims and closed loop functions.

    These new computer will give you permanent trouble codes with the rear sensors removed, even if the codes are set to no error reported. That really won't matter in your case.

    If it was me I'd keep the rear o2 sensors and just leave the sensors plugged in so the circuit is not open. Disable the cat test, cat over temp and cat codes/rear o2 sensor codes. Then carry on like normal.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    Lets start with the simple question. Do you have hptuners?

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    Quote Originally Posted by JKLTGuy View Post
    ... I live in Canada so can get away with the delete of CATs...
    Actually - no, you cannot legally operate your 2008 Jeep without catalytic converters, anywhere within Canada.

    Some areas no longer require biannual emission testing to obtain licence plate validation.

    However, the Environmental Protection Act applies nationally. This means that at any time police or Ministry of the Environment (MOE) officers can conduct a visual examination of any vehicle.

    You would be subject to a significant fine (it used to be $465) for each emission component that is missing, bypassed, or altered.

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    Quote Originally Posted by mecanicman View Post
    Lets start with the simple question. Do you have hptuners?
    I personally do not have HP Tuners yet but have a person who can do the work for me who has the unit and software. I am going to buy my own soon. Spilling $$$$ trying to finish this project.

    So the CATs should stay? If that is the case I will buy 2 and just leave the downstream sensors in. ECU is set up for that. Might be easier for now and it is only a Jeep but will have loads of power. Not looking to go over the rated 355HP. Too hard on the drivetrain.

    I realise in Canada the CATs should stay but we do not have emissions testing in BC or Alberta at least.

  6. #6
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    5FDP - It sounds like I can run the rear O2 sensors in an extension bung to satisfy the ECU monitoring? Is this correct.

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    Quote Originally Posted by JKLTGuy View Post
    ... I realise in Canada the CATs should stay but we do not have emissions testing in BC or Alberta at least...
    Some areas of Canada did not conduct scheduled emission testing for the purpose of licencing a vehicle.

    However all areas of Canada require every vehicle used on a roadway to maintain all of its original emissions equipment - this is a simple visual inspection by an officer - no testing equipment required.

    Other areas of Canada discontinued scheduled emissions testing, as a 98% or 99% pass rate had been achieved. This change was contingent on all vehicle owners property maintaining the original emission equipment.

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    Quote Originally Posted by 5FDP View Post
    These new computer will give you permanent trouble codes with the rear sensors removed, even if the codes are set to no error reported. That really won't matter in your case.
    I don't think that's accurate, not the case with my car at least. I have my rear o2s completely removed with no fault codes.
    2019 C7 ZO6 M7.

  9. #9
    Tuning Addict 5FDP's Avatar
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    C'mon Jon S, literally half of the modded cars you see on the streets have no cats lol. Laws this laws that, people do what they want still.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.