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Re: engine resonance/noise

I do have a catalytic converter - same as in the US, I just hadn't thought
of an internal weld braking loose..?

The noise sounds like induction noise actually just much louder.   The cat
"blockage"? could also be a possible cause for the apparent stumble off the
line i.e. backpressure caused?  If this is it why does it start at 3000 RPM
almost precisely??? Is it boost related - running ~ 16 psi with S knobben.

On my 1986 I think the cat has been completely hollowed out due to years+
mileage and no leaded gas...

Any one else have htis experience?  If so I'll take the car to Wonder
Muffler for a new cat (or pipe)
86 5000 CDquattro 355,000 km (old family car and sometime
 autocross winner)
 89 200 quattro 275,000 km (new family car)
 90 Corrado G60 177,000 km (autocross car and wifeand kids city car)

-----Original Message-----
From: Buchholz, Steven <Steven.Buchholz@kla-tencor.com>
To: 'Colin Barfoot' <Colin_Barfoot@email.msn.com>
Date: September 29, 1999 8:42 PM
Subject: RE: engine resonance/noise

>I guess I don't know how/why you would dismiss the exhaust system so
>I figure that you probably don't have a catalytic converter on your car,
>here in the states that is one of the most common sources of resonant noise
>... usually due to a heat shield weld breaking loose.  I would recommend
>that you start by looking at your exhaust system to see if perhaps there
>isn't a punctured silencer, or a leak at one of the joints if you don't
>any heat shields.  Finally, see if you can check for broken exhaust studs
>... another common malady that can lead to noise under load ... although
>this is usually more of a sharp sound rather than a resonance ...
>Good luck on your quest!
>Steve Buchholz
>San Jose, CA (USA)