For those EV owners with engine / transmission problems; often the solution
can be found by checking the control computer with the "VW 1551" scan tool -
if you have one. The Austin dealer charges $90 just to hook one up.

Today I got a great substitute. CarComp (www.carcomp.com) makes a software
program and serial cable adapter that connects to the later VW diagnostics
ports and gives a "plain English" readout of fault conditions and engine
parameters. It can also serve as a data acquisition unit and log data to
disk for a couple of hours while you drive. Cost is $400 - $500 depending
whether you want adapters for early 90s VW.

An hour after I got mine it found the cause of my VR6 EV jumping to high
idle after idling for a long time in hot weather with the AC on. When hot
the alternator output drops, and at idle with the AC on the voltage at the
control unit slowly drops to 12 V & lower - then the idle speed jumps from
680 to 970 until you shut the engine off. Curious that the alternator light
never comes on, and the control unit doesn't log this as a fault. Thanks to
the data acquisition logging I've got graphs proving the problem.

I have no connection with CarComp - just think it's a good deal and may
solve some problems. I think I'll see if I can rent mine to the local VW
shop.

Next to find a similar logger for the Digifant....let's see: data
acquisition card, connector adapters,...?

Tom
Austin, TX
'87, '91, '97