Erratic Starting

[John Holt]

Similar problem to Tim Herilla.......


Recently, on an erratic basis, my 1990 90 coupe quattro will not start. By
this, I mean that the starter will crank but the engine will not catch.
There seems to be no logic to whether it will start. For instance, I could
try first thing in the morning and it would start. Three hours later it
would not OR I could try three days in a row and it would not start but on
the fourth day it would start and then five hours later it would not.

When it will not start, there is no spark from the coil to the distributor
but there is gas. Used a known good coil/distributor wire with no change in
the problem.  I have checked the coil module with Bentley manual and it
falls within spec. When it starts, I can drive it all day and it will start
each successive time but it is the first start of the day (whether it be
morning or night) that seems to be somewhat elusive. I've stretched my luck
far enough on long trips so the coupe is grounded, so to speak, until I
resolve this starting problem.

Living on a hill, I have twice been able to jump start the car by popping
the clutch. Difficult to start this way....  but it worked each time before
I ran out of hill. I have no idea why popping the clutch would cause the
Coupe to go from no coil spark to sparking. My only thought is that it
could be the engine timing reference sensor but I don't understand why it
would not sense the pin ( no spark) and then sense (spark) just by engaging
the clutch.

I am not able to get codes as the fuse blows immediately on insertion
before I can read codes. This is unrelated to this starting problem as the
car performed well in the past with this same fuse problem.

It may be temperature related. I bought the Coupe in August and it has
started perfectly until the last couple of weeks when the below zero
night-time temperatures are setting in ands coincidentally so has the
problem. Yesterday and today were 60F (15C) and it starts every time.


Any thoughts appreciated.

John.....