Fooling Rear O2 Sensors?

Discussion in '96+ Vortec Performance + Computer Swaps' started by 98chevy2500SS, Dec 7, 2019.

  1. b454rat

    b454rat I'm Awesome

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    I have all 4 o2s on my Yukon with no cats n still no check engine light. Now I haven’t drivin it far, ur would think it would come on sooner..
     
  2. 98chevy2500SS

    98chevy2500SS OBSessed

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    It's straight piped from the manifolds to the muffler, I think it sounds really good without the cats and the Magnaflow muffler. I would never do a full straight pipe though, I dislike the straight pipe exhaust sound, it only sounds good on a diesel, to me anyway. I am probably just going to say f*ck it and pull the bulb if the non foulers don't work. I don't usually get very many other codes than just the pesky catalyst system inefficiency codes.

    It does take some time for it to come back on, after a few shut downs and restarts, I've been told it won't come on immediately. I cleared the codes on my 97 and it took around 5, give or take, restarts to make the SES light come back on.
     
    Last edited: Dec 9, 2019
  3. Supercharged111

    Supercharged111 I'm Awesome

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    Shouldn't affect performance even if the light comes on.
     
  4. L31MaxExpress

    L31MaxExpress I'm Awesome

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    Non foulers generally will not work without cats

    My SES light has never come on for catalyst efficiency despite having metallic core high flow race cats.

    The rear 02 bungs were spaced out with a small piece of stainless pipe tig welded to the cats. The bung was tigged to the pipe. Once this was done a tiny hole was drilled into the exhaust pipe. IIRC we used a 3/16" hole. Key is just enough to get some hot exhaust gases to enter the chamber you have created but not enough to provide free exchange of the exhaust gases like a non-fouler would create.

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