It might be time to try this simple wiring bypass tool, along with your
spare ECUs.

http://www.thesamba.com/vw/forum/viewtopic.php?t=349429

Mark

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
>