re Idle Fluctuation

["Smith, Kirby A" <kirby.a.smith@lmco.com>]

You wrote:
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I am new to the list and have a question.  I own a 1988 80 quattro.
The problem I just recently started having is that the idle surges up
and down after the car is at normal operating temperature.  It doesn't
do it when the car is cold.

I took it to the Audi dealer and was told the trouble codes say it needs
a new mass air flow sensor.  They would have to order the part which
goes for $700. + and shipping, plus about an hour and a half for labor.

Does this sound reasonable?

I was also quoted $120 to replace the one dash light bulb burned out
behind my clock.(grumble-all labor)
-----------------------------
The only mass flow sensor is the whole metering head assembly.  While it can
go bad, that is rare, and more likely you have another problem.  What were
the codes.  You need to pull them yourself.  Check the ground point on the
intake manifold where the brown wires attach.  It must be rigid and tight.
You can use a clip lead from the brown leads to another ground to check
whether this affects your idle.  Also, you may have a bad O2 sensor.
Directions for checking that are to extensive to list here.  Pull your Idle
Stabilization Valve (ISV).  The ISV is to the front of the intake manifold
and has two hoses and one cable connected to it.  It needs to be clean
inside and the hoses have to not leak.  (Look below the L-shaped one for a
split.)

You can change the light bulbs yourself, but most of them require the
instrument cluster to be removed.  With practice this can be done in well
under an hour.  For a tentative first time, assume 2 hrs.  Pull on the horn
pad (but not too far) to remove it.  Pull the horn connector.  Remove the
nut holding on the steering wheel.  Scratch an alignment mark between wheel
and shaft.  Pull wheel.  Use a phillips screwdriver under the control stalk
complex to remove two screws.  Lift up the top plastic cover and leave the
rest alone.  Remove two screws under the instrument panel (they may not do
anything as the cluster plastic housing usually breaks there.)  Now gently
pull the instrument cluster and remove the connectors in the back.  They are
color coded.  Just pop up the retainer and the connector will pull out.
Remove the panel, take it to a clean area, and remove the offending lamp by
turning it about 90 degrees in some direction.  Of course before you do this
you need replacement lamps.  You want the greeen, black, orange, brown,
whatever lamps that run in the range of 0.9 to 1.2 W.  (I've forgotten which
was the stock color in that spot.) You won't notice much difference between
them.  You should also get some 2W lamps (forgot their color) when you are
acquiring the others for future repairs.  As they say, disassembly is the
reverse.  Be sure to align the steering wheel and torque to 35? ft-lbs.
(See Bentley)  Grease the horn ring lightly with vasoline if it is dry.  If
you get some ProGold or Stabilant 22 for Audi connectors, it would be good
to use that when re-installing the instrument cluster connectors.  Good
luck.

                .... Kirby   (Kirby A. Smith)
                              2 x 1988 90q
                          New Hampshire USA