Cutting the Catalytic Converter

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by 1500ExtChevy, Mar 15, 2010.

  1. 1500ExtChevy

    1500ExtChevy Rockstar

    I'm hoping someone has some insight on Catalytic Converters for me. I am looking to cut open that Cat along the welded seam and pry it open and flush out the Cats will it turn on any OBD codes? My dad has a 2500 Duramax that he did it to but no codes for him wondering if it would be the same? Thanks.
  2. hbfsbull

    hbfsbull Member

    I did this on my truck . it will throw a o2 sensor code and your service engine light will come on . You will have to put cats back on it and drive through the drive cycle before it will pass emissions this will usually take a couple hundred miles to do . My advice would be to buy another set of cats and a y pipe to swap out for emissions . Kinda expensive but it will save you a lot of time cutting and welding new cats on every year
  3. ippielb

    ippielb Epic Member 5+ Years ROTM Winner 1000 Posts

    What you can do, is take a reciprocating saw, make CLEAN cuts to cut off the cats. And then unbolt the pipe from the manifolds, and weld on flanges to each end, so that you can unbolt your cats, and take them off. And then do the same to a piece of pipe. So you can bolt and unbolt. Instead of cutting and welding. Welding is a pain in the arse if you don't unbolt the pipe from the manifolds. I know, because my exhaust has a crap load of leaks.

    I also have my cats cut off. My 02 sensors are very dirty, so my truck doesn't have the code on all the time. It just decides when it wants it on or not.
  4. vworacle

    vworacle New Member

    Go and look up oxygen sensor spacers. I have made them out of spark plug anti foulers, and used ready made ones. You can use them on the rear o2 sensors when you have a bad cat or no cat and avoid p0420 codes. This is the item number of one on ebay 140355455139
  5. Loggerhead Mike

    Loggerhead Mike Rockstar 100 Posts

    they make ho2 eleminators for that. it basically has resistors inside to send a good signal back to the pcm. their pretty cheap too
  6. 1500ExtChevy

    1500ExtChevy Rockstar

    Now what about removing the muffler on the truck? Will that increase the sound of the exhaust? Thanks again guys or gals.
  7. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    removing the muffler will make it uhhhh quite loud.... I dont know what year you have.. I know that in my 02 chevy with the 5.3 i could set off car alarms in a parking lot very easly.. And on my 88 it wasnt as bad but still loud... I wouldnt do it id just put your choice of performace muffler in if you want some more sound.
  8. GaryG

    GaryG Rockstar 100 Posts

    Where can I find these at?
  9. dannys99

    dannys99 Rockstar

    Heck with cutting the cats, just take a hammer handle and beat the ceramic out of it. I just cut mine out and put a strait pipe. Your check engine light will come on because it will think the cat is not cleaning the exhaust. As far as performance I barely noticed a difference,only on the top end, but it sure sounded a lot better. I am running no cats with 30 series flowmasters and a crossover pipe, It is prety loud.
  10. 1500ExtChevy

    1500ExtChevy Rockstar

    Yeah defintaly dont want to mess with emissions had an 02 Grand Prix GT grinded down the seem of the Cat. where it was welded pryed open that Cat. and smashed up the ceramic inside and sucked it out with a wet/dry vac and welded it closed. Unfortunately about 3 months later emissions came and well had to spend a 100 for new a Cat. and go back.

    But easier said then done I will prolly just buy my buddies wireless exhaust cutout off his 07 TB SS since it sticks half open on him he's getting rid of it for half price so thats my easy way out.

    Thanks again guys for the much informative opinions and thoughts.

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