Clogged cats??
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Clogged cats??
How can you tell if your cats are clogged,my car just started running bad again,think it might be the tune,but now I'm thinking maybe cats.I'm S/C'ed and when I get on it it goes to the 10lbs that I've always had but the exhaust sounds different and it has no power,I can feel its trying to go but something is holding it back?Waiting to get it back to the tuner but he's been real busy,maybe tommorrow,just waiting for him to call or pm me.
Melting Slicks
Joined: Mar 2006
Posts: 2,748
Likes: 376
From: South Florida FL
Open headers.
when mine was clogged, putting my hand at the tips an idle, there's a noticeable difference between airflow between the two but I also had an H-pipe. it also would hesitate when trying to rev it.
when mine was clogged, putting my hand at the tips an idle, there's a noticeable difference between airflow between the two but I also had an H-pipe. it also would hesitate when trying to rev it.
Melting Slicks
Joined: Jun 2002
Posts: 2,246
Likes: 66
From: Middletown CT
Are you running the spiral wound metal matrix type cats? A while back, one of the members posted pictures where he had blown the spiral wound metal out of the cat and it was unraveling in the X pipe. He also had an S/C. And yes, unbolting the headers should tell you if the cats or exhaust are plugged.
Last edited by Greg_E; Jun 23, 2008 at 07:13 PM.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Are you running the spiral wound metal matrix type cats? A while back, one of the members posted pictures where he had blown the spiral wound metal out of the cat and it was unraveling in the X pipe. He also had an S/C. And yes, unbolting the headers should tell you if the cats or exhaust are plugged.
Racer
Joined: Feb 2003
Posts: 332
Likes: 0
From: Ft. Lewis WA
Mine failed about 15k after the blower was installed.
I was coming home from work one night at about 3 in the morning and gunned it to pass a truck. About 5000rpm it fell on it's face!
The funny thing was that it idled pretty well and below 1500 rpm drove normally. It was lumpy at idle and the Vac guage showed about 2" less than normal. After a dyno (it was 80 HP low) we figured it out. The left side cat was completely clogged.
I replaced both of them and have had no problems since (about 45k).
Hopes this helps.
Brian-
I was coming home from work one night at about 3 in the morning and gunned it to pass a truck. About 5000rpm it fell on it's face!
The funny thing was that it idled pretty well and below 1500 rpm drove normally. It was lumpy at idle and the Vac guage showed about 2" less than normal. After a dyno (it was 80 HP low) we figured it out. The left side cat was completely clogged.
I replaced both of them and have had no problems since (about 45k).
Hopes this helps.
Brian-
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Mine failed about 15k after the blower was installed.
I was coming home from work one night at about 3 in the morning and gunned it to pass a truck. About 5000rpm it fell on it's face!
The funny thing was that it idled pretty well and below 1500 rpm drove normally. It was lumpy at idle and the Vac guage showed about 2" less than normal. After a dyno (it was 80 HP low) we figured it out. The left side cat was completely clogged.
I replaced both of them and have had no problems since (about 45k).
Hopes this helps.
So what were the other symptoms,mine does just what you are saying,when i get on it it feels like it wants to go but I can feel something holding it back,plus the exhaust sounds different,and i can feel it,it still gets 10lbs boost but the tach goes up real slow.I have about 7500mi since the S/C install.I'm going to see Tom on Wednesday,so hopefully he can figure it out,its hard to tell since i had a cam installed I've been having issues since.
Brian-
I was coming home from work one night at about 3 in the morning and gunned it to pass a truck. About 5000rpm it fell on it's face!
The funny thing was that it idled pretty well and below 1500 rpm drove normally. It was lumpy at idle and the Vac guage showed about 2" less than normal. After a dyno (it was 80 HP low) we figured it out. The left side cat was completely clogged.
I replaced both of them and have had no problems since (about 45k).
Hopes this helps.
So what were the other symptoms,mine does just what you are saying,when i get on it it feels like it wants to go but I can feel something holding it back,plus the exhaust sounds different,and i can feel it,it still gets 10lbs boost but the tach goes up real slow.I have about 7500mi since the S/C install.I'm going to see Tom on Wednesday,so hopefully he can figure it out,its hard to tell since i had a cam installed I've been having issues since.
Brian-
Racer
Joined: Feb 2003
Posts: 332
Likes: 0
From: Ft. Lewis WA
Mine had the same issues yours does. It would make a TON of noise for almost no acceleration. I was actually scared to push it any harder than I needed to drive it to a dyno. I thought I had cracked a ring land on a piston or something but it made boost earlier than it should (because of the restriction).
If I had to guess I would bet it was one of your cats.
I do my own tune now and although rich is safe, overly rich can be hard on the cats. If you are tuning for a new cam and the air/ fuel ratio was off that might have done it. Maybe. But who knows, it could have been that cats time.
Because of the exhaust cross over (X or H pipe) it's impossible to tell which side is bad. The easiest thing to do is to drop down the H or X pipe and see if there is any cat left. If not, it is downstream wedged (near the muffler is where mine ended up) causing a restriction to end all restrictions.
Good luck and please keep us posted.
Brian-
If I had to guess I would bet it was one of your cats.
I do my own tune now and although rich is safe, overly rich can be hard on the cats. If you are tuning for a new cam and the air/ fuel ratio was off that might have done it. Maybe. But who knows, it could have been that cats time.
Because of the exhaust cross over (X or H pipe) it's impossible to tell which side is bad. The easiest thing to do is to drop down the H or X pipe and see if there is any cat left. If not, it is downstream wedged (near the muffler is where mine ended up) causing a restriction to end all restrictions.
Good luck and please keep us posted.
Brian-
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Well it wasn't my cats afterall,it was as simple as a tiny pin hole in one of the new spark plug wire boots,my car started running bad maybe a week after the cam was installed and just got worse and worse,then the other day it got real bad,when I would get on it,so while on the dyno he looked at a cylinder graff and as it would get under load i would lose # 7&8,we pulled #8 plug and it looked fine,pulled the wire off #7 and he saw a little white spot on the boot,he cut the boot open and you could tell that was a problem,so anyway he put a new boot on and all that lost power is now back.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
