Rough Running 90q

[DePenning, Charles [EPM/MTN]]

Sounds like a good way to test for vac leaks- thanks. 

I wonder how bad a faulty OXS would make the car run?  If the signal is bad
from the Lambda sensor, doesn't the ECU go into failsafe mode?  Something
like 50% duty cycle or basically open-loop control?  What I am experiencing
is far worse than that- take a spark plug or two off a healthy engine and
that is what I am dealing with.  I am homing in on either massive vac leak
or back to the plugged injector(s) theory.

Thanks again for the help.

Charley



Message: 2 
Date: Sat, 20 Mar 2004 18:45:08 -0500 
From: SJ <syljay at optonline.net> 
Subject: RE: Rough Running 90q 
To: quattro at audifans.com 
Cc: Charles.DePenning at EmersonProcess.com 
Message-ID: <002901c40ed5$60ea5790$b615c444 at dell450> 
Content-Type: text/plain; charset=iso-8859-1 

How many miles do you have on the Oxygen sensor? Sounds like a funky sensor 
to me. I wrote a post on how to test an oxygen sensor on the bench. 

Vacuum leaks will usually cause hard starting. 

Easy way to check for vacuum leaks is to remove the intake boot, Cover the 
fuel distributor with plastic, put boot back on . .and blow air into the 
intake system using one of the spare ports on the boot. If its not holding 
pressure, you have a leak. 
There are two designed-for vacuum leaks. One is the fuel injector air 
shroud. The second is the PVC system on some models. Pinch off these hoses. 
Turbo cars have more complicated plumbing that I dont know much about. 

SJ 
85 Dodge PU, D-250, 318, auto 
85 Audi 4k - - sold but still on the road 
88 Audi 5kq 
90 Audi 100q 



> From: "DePenning, Charles [EPM/MTN]" 
> <Charles.DePenning at EmersonProcess.com> 
> Subject: RE: Rough Running 90q 
> 
>  Well, I think I can scratch the cat off the list as possible problems to 
my 
> poor running 90q-