Tom Faust

My around town mileage is around 18. I just flunked inspection with mildly high hydrocarbons. The inspection report sounds like a bad cat.
How does my mileage compare?
I have what seems like a lot of exhaust noise compared to my '87 Avant. Is this familiar to anyone? I understand a plugged cat will do this.
Exhaust is fairly quiet at idle. I can't hear (one bad eardrum) my '87 from 5 feet away.

SteveAngry

That mileage doesn't sound too terrible if the car is equipped with an Automatic tranny...

Have you checked the O2 sensors yet? Good possibility that they are bad...

Here's a tip that Steve Jensen suggested about testing for a plugged cat:

Remove the blue tip from the Co sniffer tube and see if that makes the car run better. If it does you may have a plugged cat...

It's quite possible that your exhaust system is just old and has alot of pinholes in it and thats what is making it so loud...?

Steve
Michigan

Jaxon

I had the same car a few years ago. It too seemed a little loud (my wife thought it sounded like a truck, I thought it had a nice rumble). My system was rock solid and I imagine yours is too. They just don't deteriorate much regardless of mileage, although Midwest salt could corrode the Heavenly Gates.

Paul Sexton

Hi Tom,

You could indeed have a plugged cat. My guess would be that the oxygen sensor is dead/carboned up. A bum oxygen sensor will make the car run really rich and, in my humble opinion, be the culprit, especially if it's the original or hasn't been replaced in the last 50-60K miles. As for the cat, you can take it off, knock all of the crap out of it with a big screwdriver or the like and bolt it back on. Makes a world of difference in how the thing runs. A lot of Audi's run cleaner without the cat.

Cheers!
Paul Sexton
89 200
86 4000S