1990 model 80----idle problem--Help

[mskwara]

Adjusted fuel mixture with 3mm wrench, and the car runs good for a short 
diatance, then it runs rich to the point that it's necessary to readjust 
for a leaner mixture. Afterwards it will run for a while, but after it 
sets awhile, it won't start because the mix is to lean. If set too lean, 
the motor will oscillate, and not be steady. Runs good at higher speeds. 
Problem started after I put another fuel pump on. Have used Huw's audi 
garage's poor running checklist   Have changed numerous parts, but to no 
avail..Gas milage has gone  down and can no longer continue to operate 
dailyto work for 80 miles. Can the screen be permanently taken out  of 
the  control pressure actuator?  Is there any  other suggestions for 
repairs.--Thanks--

> Thanks for your response  to my  request.  These are the new parts 
> that have been installed; oxygen sensor, injector seals and seats, 
> fuel and air filter, spark plugs and wires, rotor and cap, fuel pump, 
> intake gasket, throttle body gasket,  o-ring under fuel distribution 
> unit along with the large gasket for the air flow meter, and 
> temperature sensor for  ECU(located by radiator hose attached to the 
> engine).  These parts were removed from an '89 model 80 parts 
> car.--Idle stabiliser valve (cleaned),  control pressure actuator 
> (cleaned),   complete fuel distribution unit along with  air flow 
> sensor plate was initially tried, idle stabilizer(located along right 
> side of windshield),  control unit for oxygen sensor (located under 
> the dash-directly above the glove compartment), and  thermoswitch 
> (located directly above the temperature sensor).  Idle and wide open 
> throttle switches were checked  with ohmmeter, compression read 180 to 
> 210.  Found the ECU on the 90 audi underneath the controls for the 
> heat and AC, but haven't found it for the 89.   It's located in some 
> other place.  Have been trying for the past half hour to go to 
> audifans.com, but the server must be down. Can you make any sense out 
> of this car?  And if so, what direction do I go? Mike
> 89 and 90 -not a quatro-
>
>> Adjusted fuel mixture with 3mm wrench, and the car runs good for a 
>> short diatance, then it runs rich to the point that it's necessary to 
>> readjust for a leaner mixture. 
>
>
> Something is wrong ;)
>
> And what it is is that somewhere along the way your ECU is not 
> adjusting for engine temperature (which allows rich running when cold, 
> leans out as it warms, then goes into closed loop and listens to the 
> OXS when fully warm).
>
>> Problem started after I put another fuel pump on.
>
>
> Probably not related.
>
>> Have changed numerous parts, but to no avail...
>
>
> I am curious what is now new.
>
> Main culprits here, besides connectors and grounds, are the ECU NTC 
> temp sender on the radiator hose flange (should be in the kilohm range 
> when cold, drops to a few hundred ohms whan warm, as I recall), or 
> possibly the ECU itself