Go catless with boost

Discussion in 'Forced Induction - 5.0L V8 Engine' started by robmustang201528, May 29, 2018.

  1. robmustang201528

    robmustang201528 15 mustang gt302blown

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    #1 robmustang201528, May 29, 2018
    Last edited: May 29, 2018
    Had my blower on less then a week. I've been getting on since I've had it but i wasn't expecting my cats to fail that fast. I have highflow ARH cats. Turned up the boost to 12lbs, made a couple pulls felt pretty good. On my way home leaving the shop, made a pull in 2nd switched to third and the car bogged, check engine light blinked a couple times and went off. Got off the next exit and drove it back to the shop. Cylinder 8 misfire code popped up on the scanner. He cleared the code, ran a couple test everything checked out fine but the car didn't have the same sound that I'm used to hearing. Took it back to shop. Took the exhaust down and noticed the driver side cats were 50% clogged. Cut the old cats out and welded some 3in stainless steel pipe in its place. Mechanic said I don't need a retune so I should be good to go. Moral of the story is get rid of your cats if you have a supercharger. I hope I didn't mess anything up 20180529_223354.jpg
     
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  2. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    Trying to figure out to post a pic on here
     
  3. Crackerjack17

    Crackerjack17 Well-Known Member

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    That's a failure on the way those cats were constructed. That kind of failure is what the kook/gesi green cats are supposed to avoid.

     
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  4. venumous

    venumous Well-Known Member

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    Ive been planning on taking mine off to check them. Ive never had an issue.
     
  5. SolarFlare

    SolarFlare Well-Known Member

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    I took mine off. Happy I did
     
  6. venumous

    venumous Well-Known Member

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    Did you adjust tune at all on yours?
     
  7. stang17

    stang17 Well-Known Member

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    I melted the stock cats on the Whipple tune at about 7,000 ish miles. I chalked it up to the dealer never gapping the NGK plugs that came with the kit.

    I went ahead and put on Kooks 1 7/8 headers with their standard high-flow cats. Not even a few hundred miles later and the cats were starting to fail.

    I called Kooks and was advised the only cats that "may" hold up to supercharged/turbo high horse power applications are the GESI green cats.

    We just ended up removing all of the plugged up material and run hollow cats. No more sulfur smell and the car runs noticeably better. The Whipple tune adapted fine for no cats and my tuner only needed to make minimal changes such as rear 02 sensors CEL.

    I'm fortunate enough to live close to enough work where I put less than 5,000 miles per year on the car and am emissions exempt.

    Only drawback to not having the cats is the car got a bit raspy over 3,000 rpms. I'm trying to figure out how to get that low bass rumble I had prior with the magnaflow comp cat back and stock manifolds/cats.
     
  8. Performance nut

    Performance nut Well-Known Member

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    You can keep them, just have to tune differently. To each their own though. I rather tune with some on.
     
  9. Boduke0220

    Boduke0220 Well-Known Member

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    GT500 takeoff mufflers work very well
     
  10. AdrianMAK

    AdrianMAK Well-Known Member
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    We have seen that happen more than a few times with boosted applications. Just the nature of it, the Green Cats are supposed to handle boost although we haven't tested those ourselves. Some cats live and some don't. I will tell you that if the above picture happens and it plugs up the exhaust, the result is not going to be pretty.

    We understand some guys have no choice, but the best cat is no cat when it comes to making power.
     
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  11. SolarFlare

    SolarFlare Well-Known Member

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    None needed
     
  12. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    Now I have a cylinder 8 misfire code f##%#$ SMh. I hop I just missed up the plug. The car is still responsive. Drives normal, no weird sounds. Came on a gain when I was getting on it
     
  13. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    I hope I didn't mess up the engine. Going into panic mode right now smh
     
  14. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    3 codes just popped up P0300 P0303 P0304
     
  15. F1scamp

    F1scamp Well-Known Member

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    Well now the question in my mind is did the misfires cause the cat destruction, or did the cat destruction cause the misfires. Its weird that the misfires are on both sides of the motor. Did both cat's fail? I would definitely stop driving it until you at the very least pull the plugs and see if anything obvious is going on. Good luck man, shit like this sucks.
     
  16. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    Driverside cat failed only
     
  17. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    Changed the plugs still getting misfire codes
     
  18. stang17

    stang17 Well-Known Member

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    You said you had the blower on for less than a week. Did you do a crank relearn after install?
     
  19. OP
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    robmustang201528

    robmustang201528 15 mustang gt302blown

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    Yeah I think they did. I didn't get it tuned after I took the cats off. They said I should be fine
     
  20. F1scamp

    F1scamp Well-Known Member

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    It might have sucked the cats up into the cylinders, what did the spark plugs look like when they came out? Might be time for a leakdown and compression test.
     
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