DME Failure Modes

[Lorenfb]

John Walker's Garage asked that I post the
Porsche DME failure modes based on what
I've found in working with the 3.2 units.

My experience over the last fifteen years
has found that the Bosch-Porsche DME control
unit is extremely reliable. There are, though,
some typical problems which do occur mainly
the result of other non-design factors.

About 30% of the units I receive for repair
test OK and are returned. Many times problems
are mis-diagnosed and the DME is assumed
the problem source. Of the DME units that
are bad, the breakdown is as follows:

1. 25% are water damaged (Targa/Cabs)
2. 25% are damaged by testing or incorrect
wiring during an engine installation
3. 25% are the result of intermittent
solder connections
4. 15% are damaged by owners; trying to
fix a non-existent problem, or installing
a performance chip
5. 5% are damaged by a overcharging alt.,
shorted idle valves, or bad coils &
injectors
6. 5% fail because of component failures

More info can be found at the systemsc.com
website on the following pages; Failures
and Problems.

Good Luck
Loren
'88 3.2