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    Thread: Second O2 bypass (after cat / catalytic converter delete)

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      Second O2 bypass (after cat / catalytic converter delete)

      Originally posted by Brian.

      Available at your local automotive store. Spark Plug Non Fouler PN 42009 ($4.99)





      You now need to drill out 1 of the non foulers using a 1/2" drill bit. When finished this is what it will look like.



      Side by Side comparision of the orignal and now modified non foulers



      o2 Sensor inserted in the modified non fouler
      http://i21.photobucket.com/albums/b273/ ... heat/9.jpg[/img]
      Second, unmodified non fouler now installed on modified non fouler


      Original non fouler->Modified non fouler->o2 sensor


      Fully installed


      The idea behind it is when you remove the cat the 2nd o2 sensor is going to have too much crap reaching the sensor that isnt filtered out, which will make it think the cat has gone bad. What this does is it moves the o2 sensor further away so a limited amount of exhaust gets to the o2 sensor, it is a VERY little ammount that actually gets to the sensor but as long as it is considerably less than the primary o2 sensor then it wont cause a CEL.

      from (http://www.k-series.com/forum/showthread.php?t=8833) pics rehosted by me incase the thread/pics disappear.


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      re: Second O2 bypass (after cat / catalytic converter delete)

      Just a bump for the new blood in the forum and a question...

      In the PN42009 kit, are we supposed to use the washers that come with?
      I thought, in the past, I read that a washer or two was used. Any input?

      Thanks
      Jason

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      re: Second O2 bypass (after cat / catalytic converter delete)

      So I'm thinking about doing this in the next few days.... I'm planning on getting a "highEST flow cat" possible, i.e. piece of pipe the same diameter as the pipe before/after the cat with two flanges to fit that in there... It's a cheaper version of cat-delete header... I was deciding for a while, but I just don't see myself spending 370 bucks right now on a header that gives me 11 hp... $50 bucks - another story.

      This is a great write up and I hope it works for me too, because I'm almost sure I'll get a CEL as soon as I take out the cat and put in a piece of pipe....

      Edit: just found out that what I'm having ideas about is called a "test pipe".
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      re: Second O2 bypass (after cat / catalytic converter delete)

      you probably wont get the same gain as its not really just the cat that makes the stock set up restrictive.


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      re: Second O2 bypass (after cat / catalytic converter delete)

      True, the exhaust ports on the stock exhaust manifold are tiny and poorly machined. If you have some spare time you could pop it off and shave them a little bit for better flow. I think for my 09' I'm gonna leave the stock exhaust manifold, but do as I stated above ^, leave the cat, but then bolt a new flange to the cat and run a 2.25" straight pipe back into a Flowmaster 60 and pipe is straight out the driver's side in front of the rear tire. Should flow pretty good with no flex pipe or resonators.
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      re: Second O2 bypass (after cat / catalytic converter delete)

      Quote Originally Posted by Wolfman AK907
      True, the exhaust ports on the stock exhaust manifold are tiny and poorly machined. If you have some spare time you could pop it off and shave them a little bit for better flow. I think for my 09' I'm gonna leave the stock exhaust manifold, but do as I stated above ^, leave the cat, but then bolt a new flange to the cat and run a 2.25" straight pipe back into a Flowmaster 60 and pipe is straight out the driver's side in front of the rear tire. Should flow pretty good with no flex pipe or resonators.
      So you would be leaving the most restrictive pieces in then? Isn't the manifold and the cat two most restrictive pieces in the system? (feel free to correct me, I know that you guys have quite a bit more experience with cars than I do so I'm trying to absorb as much knowledge as I can from you while I can). My flex pipe already got replaced with a shorter one but bigger diameter (2.25" I think) and the rest of the pipe after that is pretty much straight 2.25" with one small resonator (aftermarket) and a straight through twister exhaust. So what you are saying if I did go with the test-pipe, I wouldn't see any noticeable improvement? I'm trying to weigh all my options here. Thank you for all the info.
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      re: Second O2 bypass (after cat / catalytic converter delete)

      So how restricitive is the resonator on our stock exhaust?

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      re: Second O2 bypass (after cat / catalytic converter delete)

      Quote Originally Posted by reddemonx92
      So how restricitive is the resonator on our stock exhaust?
      Which one of the two? I think our original muffler is what's doing the most restricting from the cat-back... correct me if I'm wrong.
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      re: Second O2 bypass (after cat / catalytic converter delete)

      This is the one i went with
      http://www.directtuning.com/store/pc-72599-73-blox.aspx
      cheap and i think it works better than the homemade one. I did try the nonfouler trick and yes it worked but eventually broke due to the threaded area being so thin and the vibration from the car.
      the blox one is solid though. my .02
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      re: Second O2 bypass (after cat / catalytic converter delete)

      Quote Originally Posted by one_man_jam
      This is the one i went with
      http://www.directtuning.com/store/pc-72599-73-blox.aspx
      cheap and i think it works better than the homemade one. I did try the nonfouler trick and yes it worked but eventually broke due to the threaded area being so thin and the vibration from the car.
      the blox one is solid though. my .02
      The non-fouler that I bought from the store (same part number as in the DIY above) seems to look a little different than the one above. I'm going to try it first since I already did all the drilling, but I will keep this one in mind in case this one does break. Which thread broke, the inner one that is drilled out? And also, did you use the washers/crush gaskets that came with it?

      Edit: it does look like it's a lot easier to work with though and it's the same price (unless they charge for shipping) with no drilling involved.




      2006 Chevrolet Aveo a.k.a. Holden Barina SOLD
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