164 surging theory

["Mark Jones" <jones164@xxxxxxxxxxxx>]

I too have been having the surging problem on my wife's 91 164S, more or
less pronounced for about a year now.  I've changed spark plugs several
times, O2 sensor, cleaned and recleaned the Motronic FI system wiring
contacts numerous times.  I even replaced the idle air valve with no better
results.  But the problem was never cured.  New spark plug wires recently
DID improve some of the rough running drivability problem.  At 110,000 miles
and higher oil consumption,I know it is time for new valve seals etc, so the
heads are off to be polished, ported and rebuilt.  There were "crusties" and
other evidence of oil burning inside the combustion chamber and heads, my
new hope is that an engine burning oil caused the Motronic FI system to
continually try to lean out the mixture to to keep the exhaust emissions
down to the preprogrammed levels.  Read the 'Bosch Fuel Injection & Engine
Management' book by Probst, and you'll understand this makes a lot of sense.

BTW, we are borrowing my father-in-law's non-oil consuming 35,000 mile164L
while our hi mileage 164S is apart, and was surprised his car has better
acceleration than our 164S!

I'll let you know the results when it's back on the road.

Mark Jones,
Chevy Chase, MD
91 164S (apart)
92 164L auto (my daily ride)
92 164L 5spd (her borrowed ride)
86 GTV6 track toy

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