Catalytic converters

[mcpaddleboat]

06 Chevy 1500 z71 with the 5.3, it’s my friends truck and he just cut the cats out but isn’t goin to replace them with anything for a few days. So he’s just runnin with about a foot or so of straight pipe after the exhaust manifold. I’m worried he might burn a valve. He says the truck runs better with the cats off so should we Try hollowing the cats out and welding them back. Or trashing the cats all together and weld some pipe and call it a day. Open to all suggestions

 

[HotRodPC]

Shoulda thrown a code too. He could finish off the exhaust without Cats, but may need a tune to tune the Cats out and delete. I wonder what the O2 sensors are thinking?

 

[mcpaddleboat]

Thanks I’ll get started on Welding some pipe in place. He has a programmer so I’ll look into running a tune. You don’t think he’ll burn a valve in the mean time running with open pipe that close to the block like that?

 

[Snoots]

I am not going to recommend anything illegal, but for the short term, he can take 2 large rags and stuff one in each pipe when he gets to where he's going. Then take them out when he's ready to go elsewhere.
That'll keep cool/cold air from rushing back into the pipes.

 

[84 M1008]

Shoulda thrown a code too. He could finish off the exhaust without Cats, but may need a tune to tune the Cats out and delete. I wonder what the O2 sensors are thinking?

The ECM can be re flashed to 02 delete, depending on what kind of DMV inspection is required should be considered. Re flashing makes the ECM think the o2 sensors are happy.

 

[77 K20]

I wouldn't hollow out the cats. I've done that on older vehicles and often it makes the exhaust sound "funny". The exhaust noise then just bounces around in the empty metal box that used to be the cat- and turns it into an echo chamber that can be heard.

 

[84 M1008]

I would just put some shorty headers on it if deleting the cats is the plan. A muffler shop can easily fab up a real duel exhaust system for it.

 

[436'd skylark]

He won't hurt any valves like that. That's an old wives tale. Every race car out there is running open headers..

Very little to be gained by cutting the cats out. Just a harder time trying to pass inspection really. As mentioned the turbulence created by the air bouncing around the empty cat is hurting more than the functioning cat.

 

[84 M1008]

Some states don't require an emissions test, just a safety inspection. Lights, brakes, ect. I was going to buy a beautiful 96 1500 short bed from NJ, but the cats and o2 sensors were removed. That wouldn't fly in NY. One emission code here is a failure.

 

[mcpaddleboat]

Yea an emissions test in not a problem we’re in Alabama lol. When we cut them out one of the cats didn’t even have a screen in it. And the other was just super clogged. It’s throwin the low circuit voltage code today which is normal. The truck runs a lot better without them in but I was just worried about a valve thanks all

 

[Derrick]

Now, of course, this is for "offroad use only" but I would put exhaust pipe were the cats were and for the light on the dash try this

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[HotRodPC]

Some states don't require an emissions test, just a safety inspection. Lights, brakes, ect. I was going to buy a beautiful 96 1500 short bed from NJ, but the cats and o2 sensors were removed. That wouldn't fly in NY. One emission code here is a failure.

Same in Cali. Check Engine or Service Engine Soon light on = FAIL. However, if it can pass the visual, no codes, and pass the sniffer test, then you're good to go. They don't ask or check the Converters to see if they work. If they are present, then PASS. But you're engine better be running pretty clean to pass the tailpipe sniffer without Cats.

 

[84 M1008]

Wow, still sniffer emissions in California?

 

[84 M1008]

Hotrod, how is the sniffer inspection done, the put the car on the treadmill? N.Y. stopped that years ago.

 

[HotRodPC]

Hotrod, how is the sniffer inspection done, the put the car on the treadmill? N.Y. stopped that years ago.

Now you're about to catch me in a lie. I haven't smogged cars in Cali since 1990 when I moved out of Cali. So I'm far from up to date on their current laws and procedures.