Rough Running 90q

DePenning, Charles [EPM/MTN] Charles.DePenning at
Fri Mar 19 09:48:11 EST 2004

Hey- another '83 5kT owner!  Not too many of us left of the Type 43 fold.
Wish mine wasn't such a rust-bucket- I love the Teutonic version of styling
and the simplicity of the mechanical systems.  But it gets lighter every
time I drive it!

So what clogs a catalytic converter?  I can only imagine parts of the cat
itself that has broken off.  What else could get into the system- the
exhaust upstream of the cat is all SST, so no rust.  On my '83, I 'cleaned
out' the cat- what some folks would refer to 'broom-handling' it, except I
used a air hammer.  Maybe I should do that to my 90q as well. 

Thanks for the input- if you need any help on the 5000, let me know- I know
that car better than any other I've ever had.     


'89 90q
'84 4kq
'83 5kT

-----Original Message-----
From: TEX TERRY, II [mailto:texactii at] 
Sent: Friday, March 19, 2004 7:01 AM
To: Charles.DePenning at
Subject: Re: Rough Running 90q

Hi Charles  -  I receive the digest form of the list, so little bit late in

Did you ever get any helpful response (to your message below), or do you
still have the problem?  Since you said that you had very little difference
(in engine running) when you pulled each spark plug lead, I would guess that
all the cylinders are firing.  This would also mean that you do not have any
clogged injectors.  The build up of the back pressure, caused by a clogged
catalytic convertor, can definetly give the same symptoms you are having.  I
had this happen on my '83 5kt.  I disconnected the cat, cleaned it out, put
it back on (just for test purposes), and it made all the difference in the
world.  Due to many different items coming up, I have not been able to
finish working on the car (think I have a faulty cold start injector now),
but hopefully I will have it back on the road this summer.

Tex Terry, II
83 5kt sedan (non-quattro)
Franklin, PA  USA

> Message: 4
> Date: Thu, 18 Mar 2004 11:24:05 -0600
> From: "DePenning, Charles [EPM/MTN]"
> 	<Charles.DePenning at>
> Subject: Rough Running 90q
> To: "'quattro at'" <quattro at>
> Message-ID:
<619264F5DAF02344BC3B7F279A474245071684C8 at>

> Content-Type: text/plain
> Hiya, I'm looking for some technical help with my '89 90q.  Here are 
> the
> symptoms:  Starts ok cold & warm, but runs very rough, like it is 
> missing
> one or more cylinders.  It idles ok some of the time, then devolves 
> into roughness, shaking, sputtering.  If I rev it up a bit and hold 
> the
> at a set position, say, 2500 rpm, it smoothes right out, but getting
> is rough.  Driving- no power.  Moving it around my driveway is an
> in patience and lots of revs.  This happened suddenly-  I was driving 
> at highway speed and it just started this behavior and it's been this 
> way
for a
> couple of weeks.
> Here's what I have checked:  Pulled a 4444 from ECU.  Fuel system
> great, good bleed down pressure.  Great compression for 234,000 miles, 
> across all cylinders.  Plugs look good.  Pulled spark plug wires off 
> one
> a time, no discernable difference.  Air filter ok.  Pulled oil filler 
> cap off, didn't die right away, but started getting there.  Visually 
> checked vacuum system for leaks (not that that says much).  Tried the 
> propane
> vac leak detection method- no increase in idle speed noticed.
> So, I've got a couple of ideas:  blocked cat, big vacuum leak that I
> found, one or more plugged injectors.  The fact that this started so 
> suddenly is what is throwing me a little into the realm of blocked
> or ripped hose somewhere.
> Whatdya think?
> Thanks in advance!
> Charley DePenning
> '89 90q
> '84 4kq
> '83 5kT
> ------------------------------

More information about the quattro mailing list