Tacoma Dude

Hey everyone,

So today I finally got a chance to get a cracked exhaust taken care of. The segment of pipe that was affected was before the cat. On the drive home I was noticing that I had considerably more power - with the leak it felt as if my pressure plate was oil soaked or something - the engine rev didn't seem proportionate to the speed I was getting.

My question is - if my cat is gutted would I feel this return of power or would the lack of back pressure give me a similar feeling from before?

Anyhow, it's nice to have it sealed up - no noxious fumes rolling into the cab, some engine power restored, and a nice deep mellow sound returning to my muffler

jimbo74

gutting the cat is a bad idea... will fail inspection and will also release noxious gasses into the atmosphere.... its jsut dumb to do so....

Tacoma Dude

oh yeah, I should have specified...

I bought this 1st gen used and I have no idea if the previous owner gutted the cat or not. I have no way of telling so I was just wondering someone could tell me if there was any way to tell based on my experience of having the crack in that exhaust pre-cat.

Yeah, I totally agree - gutting the cat is a phenomenally idiotic thing to do. I'd like to know so I can put one back on if that's the case for me.
I have a sneaking suspicion that the previous owner had a backhanded deal with a smog tester and got it "okay'd" when it really shouldn't have passed :pat:

jimbo74

ah..... smart man... if it is gutted, you may feel a slight loss in power by replacing it with a proper one... however most manufacturers today use relatively high flow cats... they arent as restrictive as those of days past

Bigkahuna808

When I pulled my cat, I lost power. And kissed my o2 sensors goodbye. DONT DO IT, put a high flow cat in

outdoorfever

yea please find out quickly, but i know they are expensive.

Tacoma Dude

Okay - let me rephrase and simplify my question - looks like there's a little confusion as to what I was asking.

Is there a way to tell if the cat was gutted - short of pulling it out?
I noticed a certain performance loss when I had exhaust free-flowing out of the pipe pre-cat, I was just wondering if that's what it would feel like if my cat was gutted.

Oh and yes, I'm a strong supporter of leaving the cat the way it is so I'm not interested in gutting. I just want to know what the previous joker did to the rig before he sold it to me.

Maddog

I dont have a cat at all
What do you mean about the o2 sensors ?

Bigkahuna808

On 3gen 4runners and tacoma they use OBDII which I think has 2 o2 sensors. One before the cat for a dirty reading and one after that cat takes a clean reading. When I pulled my cat, and replaced it with a cherry bomb, my 2nd o2 sensor gave out. When this happens the check engine light comes on.

Aside from that I dont think thier is a way to know if its been gutted. The only evidence is that does it look like the car was removed from the car, and welded back in. Other wise there shouldnt be aftermarket welds close to the cat itself

MODZILLA

Short of pulling the cat, I doubt there is a definative way to determine it's integrity. My advice would be to start planning a custom exhaust set up that will add performance and send proper data to your ECU.

Tacoma Dude

I was afraid of this...

While I was at the shop the guy working on my rig pointed out the aftermarket cat saying that it was a universal fit that you can find in any auto shop. The only issue I have is that I'm not sure what's going to be the problem when it comes time to smog. I may have to replace everything that's in that route in order to find what the problem is :pat:

MTL_4runner

There is a way to check if the cat has been gutted and it is the same test exhaust shups use to check and see if you cat is clogged. It is a very simple test to do, you just drill a hole in front and behind the cat and use a pressure gage to check both holes. If there is no guts in the cat the pressure will be the same. All cats (even the high flow type will have some pressure drop.....aka back pressure.....which is why some engines run crappy when you remove the cat innards) will have a pressure drop to them. Just be sure to plug the other hole while taking a reading.

MODZILLA

just because it's a universal aftermarket cat doesn't automatically indicate to me that it has been gutted or bad. In fact someone would have to be crazy to spend money on a new cat and rip it's guts out when they could just remove the old one and gut it for free.

Flamedx4

Just because it's a universal aftermarket cat doesn't mean the vehicle won't pass smog either. I'd never buy a factory cat when I can put in a uni for 1/5 the money... Same with mufflers and exhaust pipes.

PirateFins

I just replaced my cat on Sat. with a direct fit bolt on from Napa, cost $124.00. My old cat was gutting itself (breaking apart inside, I could hear the guts rattling around when I banged on it) causing to much back pressure. I only noticed this when I too fixed an exhaust leak before the cat and my milage and power went down. Now I am back up to where I was before, if not slightly better.

CynicX

or you could gut your cat and move to SC, we dont have smog....hell, you can incinerate old tires and garbage in your back yard without a permit if you really wanted too.....

I used to own a WRX, which has three cats....part of the staged upgrades involved removing the cats. Just removing the cats w/o tuning the car to it made it run like a raped ape after the tune it was like a whole new car, felt like I dropped a new engine in it...of course it was turbocharged so the turbo made all the backpressure you'd ever need....

Maddog

Tacoma dude >> Its sounds more likely that you cat is just cloged ,not gutted,
A gutted cat wont make your car go worse.there would be nothing stopping the air flow from gettting through if it was gutted,BackPressure is not an issue,Infact its a myth, But i dont have time to explain it.
Now that you have fixed the leak,all of the air is trying to go through the cat ,& for some reason the cat isnt letting it get through as well as it could.

That my 2 cents anyway

Tacoma Dude

Okay if my cat is clogged would that explain the carbon flakes that are coming out in the exhaust?

I'll have to find some Seafoam and see if that helps any.

CynicX

i doubt seafoam will help unclog a cat.....maybe need to replace it.....

Tacoma Dude

I meant the Seafoam for the carbon flakes coming out - I'd like to clean out the large amount I most likely have in there. I'm around 150K.

I know the Seafoam doesn't work for the cat - I was typing out as I was thinking and didn't phrase it correctly