At 12:32 AM 2/28/2011, Old Volks Home wrote:
>Digijet ECUs are abit more robust than the Digifant successor in my
>experience.

Since they don't have to deal with the ignition system they are both
a good deal simpler and have one fewer high-current driver transistor
subject to failure.  But the Bosh version in my '84 had at least one
heavy resistor mounted well off the board (because it got hot) and I
had trouble with that, with a biggish diode nearby, and with IIRC the
legs on at least one of the big driver or voltage regulator packages.

The 2.1s have two boards and to my utter amazement one of the trouble
points was at the thin flexible paper-foil-paper sandwiches with ?30?
pins or so connecting those boards together.  These are extremely
lightweight and the stress is relieved by an S curve, so I refuse to
believe that thermal cycling had anything at all to do with these
particular failures - but I'm almost astounded that vibration could
have bothered them.  I'd love to see stroboscopic pictures of the
behavior of those things at various engine and road speeds.

One make had a more successful design in that regard than the other,
I forget which.  T-A better I think.  But overall I found lots of bad
joints in either make of 2.1l ECU, even though the T-A ones had
somewhat better looking solder off the wave machine.

Yrs,
David