Check the pin outs on the ECU plug per the Bentley manual.  It could be
a bad ground or a bad wire.  Not sure why it will only start on the
crappy ECU.  That is the weird part but it could be a coincidence that a
bad wire was just in the right position with the crappy ECU installed
and when you put in the others it is on a different angle.  Just a thought.

Ken Wilford
John 3:16
www.vanagain.com

miguel pacheco wrote:
> I'm helping with a problem on an 86 Syncro GL. This thing has a new
> Distributor, Temp II Sensor, O2 Sensor, Plugs. After installing these,
> the engine would still die when it hit a bump. It was eventually
> discovered that tapping on the ECU would kill the engine. To re-start,
> it would require much tapping on the ECU, once again. Upon request, I
> showed up on the scene with 4 used ECUs. These were all tested on my
> 86 Syncro and all worked fine. Well, that engine would not start with
> any of my ECUs. It would only start, eventually and with enough
> tapping, on the original, shaky ECU. Any ideas?
> Thanks,
> Miguel
>
> 'In heaven all the interesting people are missing.'
>   - Friedrich Nietzsche
>
>