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2002 gmc envoy_sle
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Discussion Starter · #1 ·
If you didnt read my thread about my cat converter problems heres the thread - http://forums.trailvoy.com/showthread.php?t=55890
In short it was rattling alot and had the rotten egg smell. Made the car sound like junk!

Alright I went at it on my own today with great results. I priced out a bunch of cats and was going to get the universal magnaflow but decided to just gut mine out instead. So I unbolted the pipe with the cat and took it off which was a little harder than expected. I had to take the driveshaft off to move the muffler over and unbolt the hanger on the Transmission. Then, instead of unbolting the trans crossmember, I cut one hanger hook off of the exhaust pipe to get it out. I welded it back on after I was finished. Much easier than messing with that crossmember. Now with the pipe on the ground, I cut the cat right at the front of it and took a look inside. Well I immediately saw what was rattling so bad. It was broken into 3 pieces. It is a very interesing piece. There were all kinds of metals inside that looked like gold and platinum. And the filter type piece that was busted up. The whole thing just pretty much fell right out. Man is it ever restrictive. I could barely see through it. For those of you who say these cats arent very restrictive, well I dont know what to say other than good god, thats the most restrictive POS I've ever seen. So I knocked it all out of there and welded it back up. Installed the whole pipe, used the spark plug foulers on the O2, and started it up. It ran GREAT! No more rattling, No more rotten eggs, No SES light, and it only cost me $5!! Drove it about 30 miles and no SES light. Im so glad I did this rather than replacing the cat. I will never have to worry about this part going bad again and it runs like new again. So much better than spending $100 for a cat or $600 or more at the dealer. If you have the tools and know how I would definitely recommend this. I know 98% of members here say removing or gutting the cat is a big no no but I say do it. My truck runs awesome and I'll never have to worry about any stinkin cats!!:woot::woot:
Thoughts? Opinions?
 

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2007 chevy trailblazer_ls
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1,422 Posts
Question for you did you use O2 sims or have codes deleted for the sensor? You might not get a code right away as pcm has to go thru a certain amount of drive cycles. But how does it sound? Any sound clips?
 

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2004 chevy trailblazer_lt_ext
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im thinking by the time he gets to work tomorrow the light will be on. unless you you use some sort of O2 sensor simulator its gonna throw a code. my brother did it to his supercharged buick regal gs, and within 100 miles the light was on, running like crap. once he put the O2 sims in place the computer never knew a difference.

good luck though
 

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2003 chevy trailblazer_lt_ext
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It is not legal to do this everywhere which is why it isn't recommended. You would have to check your local laws and emissions before doing this or it can end up being very costly.
 

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2002 gmc envoy_sle
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Discussion Starter · #5 ·
I used the 2 spark plug anti fouler trick for the O2. Its still working great. I drove about 30 miles so far and the wife just got back from the store again with it. Still no SES light. I will definitely keep you guys informed though.
And 07blazerman, it sounds just a quiet as before, maybe a tiny bit louder but not enough to tell. I wanted it to stay quiet though. Thanks guys.
 

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Outlaw,(how ironic) there are no tests around here so I will be fine on that note. I know most people cant do it but I live in a smaller place.
Yeah, i saw that in your other post. I just wanted to make sure people new that first before gutting it, then failing emissions or getting a big fine telling the wrong person because they didn't know. We do have cities around Milwaukee, WI that don't require emissions testing. People will just register there cars out there so they don't have to worry about it. A few yrs back I remember hearing something that the Govt. wanted to make emissions testing for everywhere but haven't heard anything since. Obviously, with your case, it isn't everywhere. Wish it was like that here.

Good job and a cheap fix if your in the right area though. Did it get a little louder without the internals of the cat in there?
 

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Discussion Starter · #11 ·
Its a cheap trick that works on most cars. This is the $5 I spent. In the help section of most auto part stores you can find a pack of 2 18mm spark plug anti foulers. These were used on older cars that had a lot of miles, burned oil, and would foul out spark plugs for one reason or another. It spaces the spark plug further away from the head. The trick is to take one of them and drill it out with a 1/2 in. drill bit. Then, take the undrilled one and screw it into the exhaust pipe where the O2 normally goes. Then screw the drilled anti fouler into that one and finally screw the O2 into the end. My Envoy barely had enough room for the extra length. It spaces the O2 further away so it doesnt pick up all the extra flow.
 

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Discussion Starter · #12 ·
Good point OUTLAW. The exhaust didnt really get any louder. Maybe a tad louder but not enough to really notice. I saw the question of gutting the cat in almost every cat thread so I thought I would post about my experience. Definitely DO NOT do this if you have emissions checks in your area.
 

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2007 chevy trailblazer_ls
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I was just about to ask what that trick was. It seems so simple but I never heard of it before. Wish I knew of it when i had my T/A and longtubes.:D
 

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2003 chevy trailblazer_ls
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I used the 2 spark plug anti fouler trick for the O2. Its still working great. I drove about 30 miles so far and the wife just got back from the store again with it. Still no SES light. I will definitely keep you guys informed though.
And 07blazerman, it sounds just a quiet as before, maybe a tiny bit louder but not enough to tell. I wanted it to stay quiet though. Thanks guys.
what is this 2 spark plug anti fowler that you speak of i want to delete my cat but am worried about the computer throwing a code?

thanks
Will
 

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2004 gmc envoy_slt
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what is this 2 spark plug anti fowler that you speak of i want to delete my cat but am worried about the computer throwing a code?

thanks
Will
Hey Will,
Jayrod answered two posts back:::
Its a cheap trick that works on most cars. This is the $5 I spent. In the help section of most auto part stores you can find a pack of 2 18mm spark plug anti foulers. These were used on older cars that had a lot of miles, burned oil, and would foul out spark plugs for one reason or another. It spaces the spark plug further away from the head. The trick is to take one of them and drill it out with a 1/2 in. drill bit. Then, take the undrilled one and screw it into the exhaust pipe where the O2 normally goes. Then screw the drilled anti fouler into that one and finally screw the O2 into the end. My Envoy barely had enough room for the extra length. It spaces the O2 further away so it doesnt pick up all the extra flow.
From what I understand, it is a way of "placing further away" the sensor from the exhaust stream. That will take it 'out' of the cat-less stream.

Just throwing two cents in there:::
I think that unless the cat is melted, broken, restrictive, or clogged, it should be left in place.

In my opinion, the small performance gain by taking it out is not worth it, compared to the contamination your engine is putting out.
The cat makes it very, very clean by comparison.

Other than that, :crazy:
Have a good day everyone! :)

-- AJ
.
 

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Discussion Starter · #17 ·
Interesting stuff straight from Wiki -
Although catalytic converters are effective at removing hydrocarbons and other harmful emissions, most of exhaust gas leaving the engine through a catalytic converter is carbon dioxide (CO2),[5] one of the greenhouse gases indicated by the Intergovernmental Panel on Climate Change (IPCC) to be a "most likely" cause of global warming.[6] Additionally, the U.S. Environmental Protection Agency (EPA) has stated catalytic converters are a significant and growing cause of global warming, due to their release of nitrous oxide (N2O), a greenhouse gas more than 300 times more potent than carbon dioxide.[7]
Catalytic converter production requires palladium and/or platinum; a portion of the world supply of these precious metals is produced near the Russian city of Norilsk, with significant negative environmental effects.[8]

So I was right, there is some platinum in there.
 

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2003 gmc envoy_slt
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So I was right, there is some platinum in there.[/QUOTE]

That's why low life steal cats from vehicles. Some scrap yards are paying big money for old cats. Truck U on the Speed channel did a segment last week about a catalytic converter anti-theft device.
 

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I have gutted the cats in all of my previous vehicels a 96 ram, 91, sonoma, 2000 monte carlo, leaving my trailblazers alone until need be to much work for not much gain, unless it is cloged and restricting. put about 15000 miles on the monte carlo never had ses light on, ( for that atleast) as for the other trucks the lights were never off to tell lol.:m2:
 
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