Time to get a new cat/cats?
Thread Starter
Burning Brakes
Joined: Jul 2005
Posts: 758
Likes: 6
From: Gainesville, FL
Time to get a new cat/cats?
((95 LT1 6spd)) - -I know I asked this a while back when I was concerned about a cats lifespan relative to miles (yeah yeah yeah - no need for 9 lives jokes here). Anyway - my car has about 84k miles on it and was originally told they should be fine for quite a while longer (Mr. Mojo mentioned his were at about 132k or so and just fine -dont remember the exact mileage he stated).
- - - My question now is addressing whether at least one of mine could have been screwed up when my O2 sensors were destroyed to an oil leak (both problems have been fixed). I was told that during this problem I had a LOT of black smoke coming out the right exhaust side of the exhaust. Ever since it was fixed the idle hasn't been as smooth as it used to be (just a little bit of wavering in idle and sound - nothing too major). Also it doesnt seem to be quite as poweful as it was beforehand. - - - Is it possible that the cat was gunked up and that one or both of the cats should be replaced? Could they cause these symptoms? Should I replace them anyways? If so - what is the cheapest (or best value) direct replacement that will equal or improve the airflow over stock? Thanks for any help with my questions..............................
- - - My question now is addressing whether at least one of mine could have been screwed up when my O2 sensors were destroyed to an oil leak (both problems have been fixed). I was told that during this problem I had a LOT of black smoke coming out the right exhaust side of the exhaust. Ever since it was fixed the idle hasn't been as smooth as it used to be (just a little bit of wavering in idle and sound - nothing too major). Also it doesnt seem to be quite as poweful as it was beforehand. - - - Is it possible that the cat was gunked up and that one or both of the cats should be replaced? Could they cause these symptoms? Should I replace them anyways? If so - what is the cheapest (or best value) direct replacement that will equal or improve the airflow over stock? Thanks for any help with my questions..............................
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by 4REGT4
- - - My question now is addressing whether at least one of mine could have been screwed up when my O2 sensors were destroyed to an oil leak (both problems have been fixed).
RACE ON!!!
Thread Starter
Burning Brakes
Joined: Jul 2005
Posts: 758
Likes: 6
From: Gainesville, FL
Sorry for my ignorance, but how would I go about testing them?? I have never had any experience with any cat equipped vehicles. As I've mentioned before - I WAS looking for a good 69 before I was forced into making a decision based on what was available. I'd replace them with staraight pipes if I wasnt worried about cops (I am putting on Flowmaster Super 40s very soon). I suppose if the Flows arent too loud or ahve too much int res. I may consider straight pipes in place of them.... as for 2k on cats...I would be cutting and welding everything myself.. just dont know anything about what to get.
Race Director
Joined: Feb 2003
Posts: 11,672
Likes: 20
From: Lake Wylie SC
I'm not sure about FL and their inspection requirements. It seems that Random Tech makes a good high flow cat for our Vettes. When you start the replacement, that would be a good time to drop in a set of long tube headers. I don't think you'll like the Flowmaster 40 series as the resonance is horrible. This is what I think you should go with for starters: Long tube headers, random high flow cats, connected to your OEM exhaust. If you want some fun noise, go with some muffler eliminators. If you want to spend lots of cash, slap on a set of Corsa or B&B catback systems. Both look and sound pretty good.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by CFI-EFI
Check the back pressure.
RACE ON!!!
RACE ON!!!
CFI, how do you test for back pressure?when i replaced my cats last year, i could barely see daylight looking through my old passenger side cat, which i suspected was bad. i think that black soot from rich running engine collects and builds up in the honeycomb. New high flow cats and O2 sensors(i was getting O2 error code for right side) made a vast improvement in idle and overall driveability. i had about 68K miles when i replaced.
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
You have conditions that would lead to a partially pluged cat, bad O2 sensor, oil in the exhaust and lack of power.
The only way to test for a restricted cat is to disconnect it and see if the power comes back.
Since you can weld, you could temporarily put in a piece of pipe so that you can road test it. If the power comes back and the idle smoothes out you know that it is time to replace it.
If the power does not come back it is not the cats, however you could still have a restriction in the exhaust at the mufflers.
See my post in "what does it take to plug a cat", kind of long but it may help. I might expand on it and start a new thresd with some facts on cats.
Hope this helps
Jerris
The only way to test for a restricted cat is to disconnect it and see if the power comes back.
Since you can weld, you could temporarily put in a piece of pipe so that you can road test it. If the power comes back and the idle smoothes out you know that it is time to replace it.
If the power does not come back it is not the cats, however you could still have a restriction in the exhaust at the mufflers.
See my post in "what does it take to plug a cat", kind of long but it may help. I might expand on it and start a new thresd with some facts on cats.
Hope this helps
Jerris
Thread Starter
Burning Brakes
Joined: Jul 2005
Posts: 758
Likes: 6
From: Gainesville, FL
Originally Posted by Strick
I'm not sure about FL and their inspection requirements. It seems that Random Tech makes a good high flow cat for our Vettes. When you start the replacement, that would be a good time to drop in a set of long tube headers. I don't think you'll like the Flowmaster 40 series as the resonance is horrible. This is what I think you should go with for starters: Long tube headers, random high flow cats, connected to your OEM exhaust. If you want some fun noise, go with some muffler eliminators. If you want to spend lots of cash, slap on a set of Corsa or B&B catback systems. Both look and sound pretty good.
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