Just bought a 90Qs 20V with a "few" issues.

[Huw Powell]

My turn to chime in...

> I just bought a beautiful '91 Audi 90Q. It has every option but came for a
> low price due to a bunch of minor issues.
> 
> I have driven the car bout 50 miles now and I got a list of questions/issues
> that I hope the group can help me with...
> 
> #1 Driver side door lock does not work. I hope that this is the same problem
> as described in this article:
> http://members.aol.com/c1j1miller/body.html#Door%20Lock%20Repair

Almost surely - the symptom for that is that the key will not lock or 
unlock the door.  The lock works from inside, and probably still from 
the passenger side.

> #2 Engine coolant gauge does not seem to be working - it is always showing
> low. However, at the same time, the car heater is not very hot. The radiator
> and engine get *warm* but not as hot as I would expect. I bought a new
> thermostat - something tells me that the one in there is stuck open...

Warm up the car from cold while feeling the top hose and radiator.  If 
the tstat is good, the radiator stays cold until the engine is quite 
warm.  If it's bad or open, the radiator will start to slowly warm up 
right from the beginning.

> #3 The oil temp gauge is also showing 60c and does not move. I refuse to
> believe this number - must be broken - please instruct how to test/fix.

Measure oil temperature with another device.  Check wiring at sender 
under the oil pump.  Check 12v supply and ground at gauges.

> #4 Driver side rear window does not roll down. Please advice on common
> causes.

Bad switch at door or drivers door; broken wiring in driver's or suspect 
door boot.  Or, bad window regulator.

> #5 Driver side headlight cracked - please advise a good source for a
> replacement. Are there any improved "euro" or other headlights that I should
> look at getting?

Dealer, ebay, craigslist, or, yes, euro lights.  Add google to the list 
of sourcing resources.

> #6 One of the foglights is also cracked - where should I get it?

The dealer or a decent foreign auto parts place.  About $70 or so.

> #7 I might need to post a picture of this as it's hard to describe...
> Between the front bumper and the grill there is a molding stripe that is
> held down by two screws located behind the headlight washers. The covers
> that go over these screws are missing - where do I get them?

Junkyard, recycler (Force Five); or dealer.  You'll probably have to 
paint them.

> #8 I own a pair of Audi 4000's nether of which I have driven much lately. It
> may be that I am just spoiled by my VR4 daily driver (Dynoed at 380hp 420tq
> on the ground), but My Audi 90 is feeling a bit under-powered to me. The
> engine feels and sounds strong, but the power is just not there... I checked
> the air filter... Seemed ok... I have driven a 90 a few years and I remember
> it having quite a bit more power... Any ideas?

You're used to your daily driver, yes.  It has almost 2.5 times the 
power.  You'll notice that.

> #9 It seems that by design, the rear diff lock disengages at a certain speed
> around 20mph. This is very annoying! I would like to keep the diff locked
> when playing in the gravel at 60-80mph. How to I override this "feature"?

Covered in detail already.  BTW, if you routinely play in gravel at 
60-80 mph, don't bother fixing any of the little things you've 
mentioned, you'll either break them again or the car itself will start 
to die.

> #10 The E-brake completely does not work. When pulling the handle, I feel no
> resistance. Common possible issues?

Covered, I believe.  It's an ebrake - check the cables and rear calipers.

> #11 The Oil pressure gauge gets pegged at 5BAR at around 3000RPM. Is this
> normal or is the gauge not working properly? The gauge response also seems
> very slow. I have Greddy gauges in my VR4, which seem to react much more in
> tune with RPM.

5 bar is where the relief valve kicks in, you should get it by 3k rpm. 
Warm, you should see at least 3 bar at idle.

> #12 Again, maybe I am just not used to it, but this motor seems to have an
> issue with running momentum - as if the flywheel is REALLY heavy. When
> hitting the clutch, it takes it quite a long time to rev down. I am used to
> downshifting when getting off a freeway or coming to a red light. In this
> car it does not work so well as the engine tends to want to keep running and
> does not slow the car much for 2-4 seconds... Is this normal?

There is a dashpot on the throttle body that eases the butterfly's 
motion to the rest position.  Things could also be gooey in there.  Oh 
wait, that's the 10v.  Not sure how the 20v is set up.

> #13 The back of the passenger headlight seems to have a hose that leads to
> the header heatshield. Could someone please explain to me what the heck this
> is and what's it for?

Intake air?  How big is it?

> #14 Although they worked on the test drive, my high beams do not work at
> all. When turning them on, the low beams cut out and I have no light.
> Tapping the passing light switch does nothing. I will check fuses and relays
> tomorrow. Any description of where to locate them would be of much help...

Fuses are in fuse box, label on lid.  No relays.

> #15 The driver side front seat has seen better days. What's the solution? 

A used seat in better condition.  See Force Five or a local dismantler, 
or the audifans marketplace.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/