Re: 1986 4000 CSQ OXS problem

["Christopher P. Locke" <d.locke@snet.net>]

Steve Dambrowski wrote:
> 
> Car: 1986 Audi 4000 CSQ
> Miles: 170k
> 
> I thought I posted this last night, but I don't see it here on the server.
> 
> My OXS light came on two days ago, and when I went to start the car
> yesturday, it took forever before it finally stayed running. (about 15
> min) Then I had to let it warm up and I was finally able to drive it home.
> It ran really bad until I was a block from home, then everything returned
> to normal. (figures, huh?)
> 

My first guess is differential pressure regulator.  If the engine is
warm, and the dpr isn't working, it'll start, but run really lean. 
Hence the "limp home mode" for the CIS-E.  IF the engine is cold, it'll
take an act of God to start the car and it'll run lean until it's
fixed.  The systm is basically running open loop, even though there's
feedback from the 02 sensor, the computer cant do anything with the
signals, since the mechanism for changing the mixture is dead.  get the
car running, warm it up, and then unplug the DPR, if the idle changes,
the DPR is (usually pretty) good, if it doesn't change, change the dpr
from the parts car

Chris Locke 86 4kcstq