89 200 Turbo SAGA goes on ...

[David Conner]

Fay asks...
"Are you saying it is the Turbo which is not working."

Hi Fay,
No, that's not what I'm saying.  What I'm saying is you have a 16 year old
Audi with a turbo attached to the engine.  Turbos create a >lot< of extra
of heat and stress under the hood.  Your car likely has multiple problems.
Maybe a single one is causing it not to start, but there could very well be
a number of poor electrical connections, etc that are degrading performance.  

Compared to a non-turbo engine there are more electrical sensors, wiring
and hoses under the hood.  The turbo generates an extreme amount of heat
which takes a toll on hoses, wiring, plastic, and everything else under the
hood.  The turbo creates a lot of >pressure< in the air intake system which
will cause failure of age/heat weakened components (hoses).  The heat
stress can also lead to a cracked exhaust manifold.  Leaks or cracks both
result in vacuum leaks which cause poor running or no-start condition.  The
turbo pressure >will< blow off a hose if a clamp was accidentally left too
loose.  (A hose clamp could accidentally be left loose by even the most
competent and honest mechanic, BTW.)  Access to many of these hoses and
clamps is difficult and some are impossible to see.  Even if you can see
the clamp, maybe you can't reach it.  A loose clamp may not >look< loose.
You had a recent timing belt replacement... this would require removal of
the intercooler and attendant hoses.  One of these clamps that you can
barely see, let alone reach, may be loose and later the hose blew off.   A
non-turbo engine does not have an intercooler and does not blow the hoses
off or rupture old hoses the way pressure form a turbo will.  Another thing
on the turbo engine which may have been disturbed during timing belt
replacement is the wiring/connector for the intercooler temp sensor.  If
the fragile little wires here are damaged they will short out this sensor
and rob your engine of power. 

Did your car spend years in the rust/salt belt?  If so, this creates more
problems.  Sixteen years of high underhood temps causes deteriorated wire
insulation and connectors.  A poor connection on a single sensor is a
problem.  Cracked wire insulation and hardened rubber wiring connectors
allow salt to enter and corrode the electricals.  Access to some of these
sensors and wiring is difficult.  You cannot afford to replace all the
things on your car that could cause problems in hopes that one of these
things will fix it.  A methodical approach is needed where a problem is
narrowed down to it's source and dealt with.

Let me give an example from recent experience with my own 89 200Q that
improved performance...
The real problem which prevented the engine from running was a loose clamp
on one of the intercooler hoses... one of the clamps that is hard to see
and difficult to reach.  No doubt it was me who failed to tighten the
clamp.  When I tested for spark it appeared to be either no-spark or weak
spark.  I narrowed the problem down to the coil so I removed it to swap a
known good coil to see if that would help.  It didn't help because my
>real< problem was a loose hose clamp.  I examined the old coil and found a
surprise problem which I suspect is common on these cars.  There is a fat
wire connector pushed on to the bottom of the coil.  I pulled this
connector and found >way< too much green corrosion on it.  This wire
connector would be difficult to examine without removing the coil from the
car, and coil R&R is not easy, so I had never examined it before.  The
rubber connector boot here is supposed to seal out water but was hardened
from old age and no longer doing it's job.  I cleaned up the corrosion,
smeared di-electric grease around the rubber bootie and re-installed it in
the car.  Still no start.  Then I found the loose hose clamp and tightened
it.  Now the car not only starts and runs, but it starts and runs much
better than before.  So... I had two problems... one which prevented the
engine from running at all (loose hose), and a second one which caused weak
spark and reduced performance.  In the end I didn't install a single new
part, but having some known good spares to swap was a big help. I also had
plenty of time to troubleshoot at my leisure since I have a spare car to
drive at all times.  Replacement of the coil with a new one, a $200-250
part, would also have fixed the weak spark.  If I had paid a competent
honest mechanic to fix my weak spark I would expect it to have cost at
>least< $300, maybe a lot more.

HTH,
Dave C.