Opinions on cutting out catalytic converters.

[AyWoSch Motors]

@AyWoSch Motors You already have all kind of opinions, and you'll continue to get more. So here are some facts for you.

Catalytic converter pros:
Cleans up your exhaust, means less smell and better for the environment.
Exhaust has a gas in it called NOx NOx dissipates quickly and is not a long term environmental hazard, however it is really good at destroying lung tissue. If your sitting in traffic or working on your truck and your smelling your exhaust you can bet your breathing that in. Ask an mechanic with COPD how he got it. probably from that and / or smoking.
Your exhaust system will last longer with a cat because there will be less acidic deposits in the muffler and pipes.
Modern catalytic converters create such little back pressure that it cannot be detected on a backpressure test.
Acts somewhat like a resonator and will mellow the tone of the exhaust somewhat.


Catalytic converter cons:
Depending on converter installed it may create a small amount of restriction
Cost money to install

So for the above reasons I have a catalytic converter on my square and also on my 77 Cadillac.

Good points, pros and cons.
At this point in time, I'll leave them on. I've gotten the opinion of "if it ain't broke dont fix it", from alot of people. And it seem like itd be doing more damage than good for the 97.

I will say this though:
I will never put on one a vehical that didnt have one from the factory, nor will I ever replace the one on my Yukon.
I currently have 10 running vehicles, and those 2 previously mentioned are the only ones that have a Cat.
I dont have a garage to park them in, to create a closed space to contaminate, I live and work in the wide open with fresh air and wind. I dont leave them running when I'm working under them.
There is no such thing as traffic to get stuck in here. I have no neighbors to upset with smell and I have no sense of smell. I dont ever have to worry about the exhaust rusting out, there's no such thing as rust here, and if it hasn't had a problem with it in 29 years/300k miles, it never will. As far as back pressure goes, that fact may be true for new cars/new cats, but as far as something 30 years old, I'm sure theres a drastic increase in back pressure from stock. I've seen what a clogged one will do, and how they can explode if they clog up completely.

I still suspect of that being one of the many reasons that my burb has no balls. May still take it off some day, but for now, I have too much on my plate to fix something that isn't broken.

I wasnt looking to put one on, just the possible effects of taking one off.

I'm not out to pollute the world, I'm conscientious about what I do and things I spill. I'm also not a environut, I'm a country boy and I like my gas pig trucks.
I may own 8 V8s, but with all the big company's out there polluting the skys and power plants and so forth, I'm not concerned with my couple trucks "stinking up the place". I am a one millionth of a percent, not gonna change anything. Plus, I can only drive one at a time.

And you forgot one pro of cutting one out: there worth good money. And for someone that doesn't have much, an extra 200 some dollars in trade for something they don't need, is worth it.

 

[Ellie Niner]

@AyWoSch Motors -You can usually tell if you have a cat melted down by listening to the exhaust... It will make a weak, hissing sound when you step on the gas under load, and you'll have less and less power the more you put your foot into it. I used to have a 1991 GMT400 3/4 ton 4wd that was a gutless pig. It was an extended cab long box, and weighed around 5800# empty. No beans at all. I've always thought that was SOP for the TBI engines, as a 1988 GMC short box 4x4 was not that much different. Felt a bit weaker than my 1986.

 

[SirRobyn0]

Good points, pros and cons.
At this point in time, I'll leave them on. I've gotten the opinion of "if it ain't broke dont fix it", from alot of people. And it seem like itd be doing more damage than good for the 97.

I will say this though:
I will never put on one a vehical that didnt have one from the factory, nor will I ever replace the one on my Yukon.
I currently have 10 running vehicles, and those 2 previously mentioned are the only ones that have a Cat.
I dont have a garage to park them in, to create a closed space to contaminate, I live and work in the wide open with fresh air and wind. I dont leave them running when I'm working under them.
There is no such thing as traffic to get stuck in here. I have no neighbors to upset with smell and I have no sense of smell. I dont ever have to worry about the exhaust rusting out, there's no such thing as rust here, and if it hasn't had a problem with it in 29 years/300k miles, it never will. As far as back pressure goes, that fact may be true for new cars/new cats, but as far as something 30 years old, I'm sure theres a drastic increase in back pressure from stock. I've seen what a clogged one will do, and how they can explode if they clog up completely.

I still suspect of that being one of the many reasons that my burb has no balls. May still take it off some day, but for now, I have too much on my plate to fix something that isn't broken.

I wasnt looking to put one on, just the possible effects of taking one off.

I'm not out to pollute the world, I'm conscientious about what I do and things I spill. I'm also not a environut, I'm a country boy and I like my gas pig trucks.
I may own 8 V8s, but with all the big company's out there polluting the skys and power plants and so forth, I'm not concerned with my couple trucks "stinking up the place". I am a one millionth of a percent, not gonna change anything. Plus, I can only drive one at a time.

And you forgot one pro of cutting one out: there worth good money. And for someone that doesn't have much, an extra 200 some dollars in trade for something they don't need, is worth it.

I missed that one was a 97, yes that will set the check light if it has an after cat O2 sensor and I'm pretty sure those do. The good news is only the up stream O2 sensors are used by the computer for fuel mixing. The downstream O2 sensors are only used for the PCM to check to see if the cats are doing their job.

As for my NOx comment, I doubt most people regular folks would get exposed to enough to cause serious damage, I mean look at all the pre-cat vehicles that from the days before cats and people didn't get lung problems from it right and left. The main reason I brought it up is because if you or someone that reads this thread in the future has a lung condition already you'd definitely want to keep those cats, and is one of the main reason my rigs all have them.

You said, "As far as back pressure goes, that fact may be true for new cars/new cats, but as far as something 30 years old, I'm sure theres a drastic increase in back pressure from stock. I've seen what a clogged one will do" If the cat is 30 years old then yes it might be causing back pressure, but that's because of build up overtime. A new cat even on an old rig will not cause a substantial amount of back pressure. I just want to be clear on that bit. The old fashion pellet type cats from the 70's did cause back pressure and were the type that typically had problems with blowing apart. That style cat has not been sold in a very long time and replacements are of a modern design.

As for the burb with power issues (I assume this is the 92) you could pull the O2 sensor out or bust the downpipes loose and take it for drive and see if the power is better. Typically in my experience a clogged cat will act normal, or somewhat normal until the engine (and cat) is warmed up and that's when the restriction takes hold and power loss is noticed. Also it usually goes from lack of power to won't go more than 15 - 25 mph over the course of a few weeks or months. Often times you'll get that smell of something hot along with it, but not always. Of course there is always the oddball that doesn't act like that.

Yea, they are worth money. Like you I live in the country and like my old trucks and V8s, but I manage a shop in the city, and it's in the warehouse area. We cannot leave vehicles outside the shop at night ever anymore. There is no visibility from the street to the parking lot and someone will come cut the cats of anything left outside.

 

[AyWoSch Motors]

I missed that one was a 97, yes that will set the check light if it has an after cat O2 sensor and I'm pretty sure those do. The good news is only the up stream O2 sensors are used by the computer for fuel mixing. The downstream O2 sensors are only used for the PCM to check to see if the cats are doing their job.

As for my NOx comment, I doubt most people regular folks would get exposed to enough to cause serious damage, I mean look at all the pre-cat vehicles that from the days before cats and people didn't get lung problems from it right and left. The main reason I brought it up is because if you or someone that reads this thread in the future has a lung condition already you'd definitely want to keep those cats, and is one of the main reason my rigs all have them.

You said, "As far as back pressure goes, that fact may be true for new cars/new cats, but as far as something 30 years old, I'm sure theres a drastic increase in back pressure from stock. I've seen what a clogged one will do" If the cat is 30 years old then yes it might be causing back pressure, but that's because of build up overtime. A new cat even on an old rig will not cause a substantial amount of back pressure. I just want to be clear on that bit. The old fashion pellet type cats from the 70's did cause back pressure and were the type that typically had problems with blowing apart. That style cat has not been sold in a very long time and replacements are of a modern design.

As for the burb with power issues (I assume this is the 92) you could pull the O2 sensor out or bust the downpipes loose and take it for drive and see if the power is better. Typically in my experience a clogged cat will act normal, or somewhat normal until the engine (and cat) is warmed up and that's when the restriction takes hold and power loss is noticed. Also it usually goes from lack of power to won't go more than 15 - 25 mph over the course of a few weeks or months. Often times you'll get that smell of something hot along with it, but not always. Of course there is always the oddball that doesn't act like that.

Yea, they are worth money. Like you I live in the country and like my old trucks and V8s, but I manage a shop in the city, and it's in the warehouse area. We cannot leave vehicles outside the shop at night ever anymore. There is no visibility from the street to the parking lot and someone will come cut the cats of anything left outside.

I've heard the stories of people going around cutting cats off in the street. I would never be the type to do that, haha.

And yes the 92 is the suburban. I would definitely do a test run to see what changes before I go sell the part. Had the thought of disconnecting the exhaust, and install an extra header y pipe I have, and run it open pipes to feel if it makes a difference.
I'm not blaming it on that 100%, I'm sure it has more to do with the fact it has a 190hp TBI 350 with 300k miles, and its hauling around 6000lbs, hahaha.
Not looking to make it a race car, but every little thing will help.

And lately I've found out the best way to give it some balls when I need it, is to downshift it manually.
I actually passed someone the other day by doing that, that surprised me.

When the one on my Yukon blew up, previous to it doing so, it wasn't running great, but the ride home, although very loud, it ran great and has ever since.

And I take lung issues very seriously, my mother has a lung disease. Hadn't thought about the effects on her, so thank you for that.
Since I drive her around in that vehical alot, it might be a good thought to leave it. Good point there.

 

[AuroraGirl]

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Although these are both heated, one on left is a 220k mile (in a car) O2 sensor and the one on right is new. there is an air source in the wiring usually so make sure the wiring to the sensor isnt kinked or pinched anywhere
also, my car hasnt been an oil burner minus some plugged PCV baffle time only when I owned it so not many miles, and evidently hasnt had any issues with O2 sensor poisoning as that tip looks worn but not problematic.

with this worn and old sensor I noticed that the speed of which the data updated was slower and it never set a code for slow switching or other issue, but when I used my scan tool after replacement I was like oh because it was so much more responsive. ultimately in the 1st o2 spot that means it will give a more accurate AFR and keep your engine in proper power and efficiency spots when in closed loop,

not sure about TBI but tp sensor is usually really important esp in responsiveness because it uses that signal for power enrichment and switching to open loop to have more fuel generally for power making. But if that sensor is not functional it would use manifold pressure from MAP and MAF data to enrich but it would be slower to engage. and without the TP Sensor fueling and supercharge boost plays with the MAF and MAP because well forced induction and also yanking in more air so it has programmed power limiters and keeps you from being brave without that sensor. what im saying is if tbi uses tp sensor for fuel enrichment and the o2 is, say, old and just slow to respond, that could be the issue, stays in closed loop too long maybe and by time it realizes you were needing power youre already been waiting for oomf and nothing happened lol

 

[diesel_lv]

On my '87 K5 350 TBI, I removed the old cat and replaced it w a modern higher flow one, a high flow muffler also. Has a nice deep base now and will also pass smog if it were required to. If your engine is fuel injected and computer controlled, removing the cat, smog pump etc... do nothing for performance and can actually put it into limp mode unless you are reprogramming the computer and making other mods to take advantage of it.

 

[diesel_lv]

81 as far as I know would have come with a cat, even Federal Emissions.

Goldie is an 80 and came with one.

1974: last yr no cat on passenger cars, 1978: last year no cat on pickup trucks based on GVW.

 

[AuroraGirl]

1974: last yr no cat on passenger cars, 1978: last year no cat on pickup trucks based on GVW.

my 80 had none. same with @Bextreme04

 

[diesel_lv]

my 80 had none. same with @Bextreme04

Oh I'm not doubting that some people have them without. I'm just saying what the law is. How people got around it, who knows. But 1978 was last year for no cat depending on GVW. '78 and older had absolutely no cat on any truck.

 

[bucket]

Oh I'm not doubting that some people have them without. I'm just saying what the law is. How people got around it, who knows. But 1978 was last year for no cat depending on GVW. '78 and older had absolutely no cat on any truck.

GM built hundreds of thousands of 3/4 and 1 ton trucks without catalytic converters all the way through '86.

 

[diesel_lv]

GM built hundreds of thousands of 3/4 and 1 ton trucks without catalytic converters all the way through '86.

Apparently no one reads, n like to argue n be right. 1978: last year no cats on trucks, Federal not just CA. After that, it was based on GVW. Which varied yr to yr.

 

[bucket]

Apparently no one reads, n like to argue n be right. 1978: last year no cats on trucks, Federal not just CA. After that, it was based on GVW. Which varied yr to yr.

Actually I did read. The way you stated it the first time seemed correct. It was your response to AuroraGirl that made it seem like all trucks after '78 had a cat. Which is why I quoted that post and not your first one.

 

[AuroraGirl]

Oh I'm not doubting that some people have them without. I'm just saying what the law is. How people got around it, who knows. But 1978 was last year for no cat depending on GVW. '78 and older had absolutely no cat on any truck.

are you sure 78 and older had no cats on truck? I thought 75 or 76 was first year 2 way cats with a lot of exceptions, but a small half ton would prob fit the bill for it, at least I thought. GM Was all over cat converters and was pretty pretentious in how they were saving the planet yada yada lol

 

[Ellie Niner]

are you sure 78 and older had no cats on truck? I thought 75 or 76 was first year 2 way cats with a lot of exceptions, but a small half ton would prob fit the bill for it, at least I thought. GM Was all over cat converters and was pretty pretentious in how they were saving the planet yada yada lol

It was based on GVW. To oversimplify, 1/2 tons got converters in 1975, while 3/4 ton up did not. They tightened it up in 1979, so most of the Heavy Half/Big 10 packages that pushed a 1/2 ton into 3/4 ton territory, no longer could meet emissions without a catalyst. As was stated, most GM vehicles over 8600GVW (I think that's the number) got by without a converter through 1986.

 

[Ellie Niner]

And lately I've found out the best way to give it some balls when I need it, is to downshift it manually.
I actually passed someone the other day by doing that, that surprised me.

That pretty much dismisses the notion of a plugged up cat. I drove a Ford Aerostar (stop laughing) with melted down converters once, and it would actually lose speed if you kicked it into passing gear. Basically anything that increased flow through the exhaust (rpm, opening throttle) would make it fall flat on its face, while it made sounds like someone jammed a potato in the tailpipe.