Hi All,

This is a posting for a solution to a cold start problem I have had.
This has been a persistent problem for awhile, and I have tried a ton
of other things (partially derived from the archives).  Yes, in the end
it was something VERY easy!

Symptom:  At 20 F or colder, engine tries to start immediately, stalls,
and floods upon further attempts to start.  No problem starting in
warmer temperatures.

Solution:  Checked voltage at coil (between pin 15 and ground) with
ignition on.  Should be battery voltage, but mine was unstable.
Removed the coil, cleaned the coil tower, wire brushed the posts on the
coil, sanded the washers and nuts, sand blasted the terminals (sanding
did not work, must have been quite a film of tarnish, dirt, and
oxidation), and cleaned push on connectors with sandpaper.

Final checks:  Checked voltage between pin 15 and ground with ignition
on; the voltage was stable after the cleaning.  Checked voltage between
pin 1 and 15 with ignition on while grounding the center connector to
the Hall sensor (per Bentley manual description) for 3 seconds or less;
voltage is around 4.5 volts I recall.

The car has been starting below 10 F now without any problems.  The
bottom line is that the spark was too weak.  When the mixture was
richened by the ECU for a low temperature start, the weak spark could
not handle the extra gasoline.  Yes, a VERY easy problem to understand
once you figure it out!

John Neumeier
'87 Syncro
'91 Westfalia

-----------------------------------------------
John J. Neumeier
Physics Department
PO Box 173840
Montana State University
Bozeman, MT  59717-3840
office telephone: 406-994-6171
lab telephone: 406-994-6148
FAX: 406-994-4452
email: neumeier@physics.montana.edu
webpage: www.physics.montana.edu/faculty/neumeier/jjn.htm