Blasphemy, add a catalytic converter??????

[bobby v]

In another thread about my truck seemingly running way rich by smell of the exhaust in the garage, upon startup especially, another member mentioned maybe it is because of the cat being removed. So I'm wondering if the other members agree ?
I've got no CEL and the 02 sensor was just replaced as well as all engine managment items and is running well.
Thanks


Bobby V

 

[RDF1]

What is your setup?
But yes without a cat you will get a rich smell.
The tune can be adjusted some to help but its not going to go away 100% because the Cat was burning off the extra gas if that makes sense.
Ive got a 5.3 with a turbo and 4" exhaust all the way out and sometimes it will give that smell while its warming up.

 

[RoJo2]

FWIW, I have a bone stock (engine) 98 Vortec 350 with true dual exhaust and twin cats... and it smells rich too when compared to my stock 2013 6.0. I can imagine without the cats it would smell very rich especially on startup when your dumping more fuel than normal operation.


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[Redneckgeriatric]

do you have short or fat exhaust tubing? there is always that. it can induce reversion that will trick the o2 sensor.

how is the ect sensor? dont trust dtc codes or the lack of..

 

[bobby v]

What is your setup?
But yes without a cat you will get a rich smell.
The tune can be adjusted some to help but its not going to go away 100% because the Cat was burning off the extra gas if that makes sense.
Ive got a 5.3 with a turbo and 4" exhaust all the way out and sometimes it will give that smell while its warming up.

Sorry should have stated what I have.
Close to stock 454 GenV ( sounds to have a small cam) done by previous owner ??
Edelbrock TBI intake manifold
Edlbrock shorty headers
3" single exhaust to the back with Flowmaster 40

I might try to get a slip fit cat just to see if it lessens the rich smell, Ive got an alarm right above where it parks and it goes off almost instantly when I start it

 

[Redneckgeriatric]

the cam will also allow more reversion. i would run smaller tubing or add cat.

 

[Cheap Heap]

My 88’ long bed has a stock 350 with dual exhaust and no cat. My 93’ step side a stock 350 with the oem cat and dual exhaust cat back. Smell is night and day between the two trucks.

 

[RDF1]

Sorry should have stated what I have.
Close to stock 454 GenV ( sounds to have a small cam) done by previous owner ??
Edelbrock TBI intake manifold
Edlbrock shorty headers
3" single exhaust to the back with Flowmaster 40

I might try to get a slip fit cat just to see if it lessens the rich smell, Ive got an alarm right above where it parks and it goes off almost instantly when I start it

Yea if it has a cam and not tuned just right it could be very bad smell.

 

[JSlezak83]

2000 Crew cab 8’ with an otherwise stock 454 4L80E. The factory cats were cut out, and it has a dual 3” exhaust that exits in front of the rear wheels. There are a pair of resonators, and a dual in/out muffler. At cold start, you can definitely smell the lack of cats. My wife doesn’t complain about the smell, so it’s can’t be that bad.

 

[Redneckgeriatric]

Yea if it has a cam and not tuned just right it could be very bad smell.

if it cant be tuned, it is built with the wrong components. as is the case of the OP