What are the symptoms of a plugged cat?
Hello all,
I blew the turbo on my '98 A4 1.8 T quattro and drove for 5,000 miles with mucho exhaust exiting the wastegate (loud) and no acceleration, no boost, no throttle response.
Last week I replaced the turbo with a remanufactured unit...but still have no boost or acceleration. I'm thinking "This engine just isn't breathing right." No blockages on the intake side.
So I'm wondering if my catalytic converter is just...90% plugged up? Adding to my suspicion are frequent noises from the cat that sound a lot like corn flakes in a tin can.[>:]
So,
1) Does it sound like a plugged cat?
2) If I'm trying to restore stock performance, how does $250 for a used cat from Dad's Auto Dismantling sound?
3) Do I want to replace my front and rear O2 sensors as a matter of course, or wait and see? There are no check engine lights on.
Thanks in advance for any advice. I know a lot about Citroens but not much about Audis.
Jeff in Boston
I blew the turbo on my '98 A4 1.8 T quattro and drove for 5,000 miles with mucho exhaust exiting the wastegate (loud) and no acceleration, no boost, no throttle response.
Last week I replaced the turbo with a remanufactured unit...but still have no boost or acceleration. I'm thinking "This engine just isn't breathing right." No blockages on the intake side.
So I'm wondering if my catalytic converter is just...90% plugged up? Adding to my suspicion are frequent noises from the cat that sound a lot like corn flakes in a tin can.[>:]
So,
1) Does it sound like a plugged cat?
2) If I'm trying to restore stock performance, how does $250 for a used cat from Dad's Auto Dismantling sound?

3) Do I want to replace my front and rear O2 sensors as a matter of course, or wait and see? There are no check engine lights on.
Thanks in advance for any advice. I know a lot about Citroens but not much about Audis.
Jeff in Boston
If you are hearing the sound you mentioned a lot, it can cause problems.
The metal pieces that break off can clog the cat / covering the exhaust port. This may cause backpressure problems, which would cause decreased performance.
I would not replace the sensors unless there is some other evidence that they are bad (codes, very poor MPG).
go to ECStining.com, you can buy a cat for $89-$99 brand new, not including installation.
In the meantime, maybe try banging on the cat with something and see if you can shake the peices around maybe uncovering the exhaust port, if there is indeed blockage there.
The metal pieces that break off can clog the cat / covering the exhaust port. This may cause backpressure problems, which would cause decreased performance.
I would not replace the sensors unless there is some other evidence that they are bad (codes, very poor MPG).
go to ECStining.com, you can buy a cat for $89-$99 brand new, not including installation.
In the meantime, maybe try banging on the cat with something and see if you can shake the peices around maybe uncovering the exhaust port, if there is indeed blockage there.
yeah i have the same issue, i remember talking to you on either vwvortex or audizine, but i said screw getting a new cat and just got a testpipe from renn-art. https://www.renn-art.com/Main.asp?make=1. they are a definite better alternative if your cat is shot, and will definetly help you feel your new turbo and are a hell of alot cheaper than a highflow or OEM cat. Once i get my testpipe installed ill let you know how it is
Thread
Thread Starter
Forum
Replies
Last Post




