Rough idle on 5kcstq

[Allan Tygert <atygert@ptc.com>]

Greetings all!

It's been a while since I subscribed (new job, new state, new internet
connection, etc).

Unfortunately, at least one thing in my life is not new; the Audi gods are
not smiling on me of late.  My 86 5kcstq is idling quite roughly.  When I
pull up to a stop sign and let off on the gas, the idle drops to about 800
to 900 rpm, the whole car shimmies, and slowly the idle comes up to ~1100rpm
before it settles in between 950 and 1000 rpm.  About 20% of the time it
dies.  Then it takes about a minute of letting the car sit before it will
reliably restart (want some fun, try this at a toll booth on the Garden
State Parkway on a Saturday morning.  Whoopi doopi!!).  The problem only
gets worse when the A/C is on.  I have had to resort to working all three
pedals at once.  While this is great practice for heel-toe breaking on the
track, it gets real old real fast in traffic.  The problem only seems to
surface when the car is warm.

I've tried putting carb cleaner (the kind that goes in the gas tank, not the
spray kind) into the two ports of the idle stabilizer valve and let it soak
for an hour and reapplied.  It came out black the first time and pretty much
the sam color it went in the second time.  I tried tapping the valve with a
screwdriver handle.  Niether gave much if any improvement.  When I unplug
the electrical connection to the valve, the car dies a slow death.

I haven't done a fuel system check yet, mainly because the injectors are
only about a year old and the fuel pump is only about a year and a half old.
I did run out of gas two or three times, which I know is not good.  Could
running the tank dry a few times be enogh to kill the pump (it does seem to
whine a little more than I remember of late)?

Can anyone suggest any other things to try to eliminate the idle stabilizer
valve before I charge head long into checking the system pressures?  Any and
all help is greatly appreciated!


Cheers!

Allan Tygert
Official Audiot
Customer Support Engineer
Parametric Technology Corporation
atygert@ptc.com