Jon,

I have been following this thread for a bit and it is exciting to
consider the possibilites. If you are able to pull this off, every
Vanagon owner everywhere is going to owe you a big one. Aging electrics
and electronics often kill older vehicles, and this particular item is
especially egregious in that  department. I have two vans with stock
2.1L WBX engines, and the Idle Control doesn't work on either one of
them. They run so sweet when they work, and the mileage is a bit better
as well.

I offer my encouragement.

Keep up the good work.

Regards,

John Rodgers
88 GL Driver x2

jon wrote:
> I recently received an ISV control unit (1986 and later) for disassembly
> (among other things). Thank you Mike!!! This research confirms several
> hunches that I had.
>
> The control unit consists of 16 op-amps (4 LM2902 quad chips), a 4 Amp PNP
> power transistor for driving the idle stabilizer valve. I would bet
> that this transistor is what fails when a control unit goes bad. This
> part, a BD438, is readily available. So, I think repair would be possible
> in most cases.
>
> My other bet is that if an IS valve shorts, it will blow the transistor.
>
> How many folks out there have a *bad* IS control unit? I'd love one to
> verify if it's the transistor that went south.
>
> The unit is much easier to open the a 1.9L IS control unit (which
> requires cutting). There are 6 clips molded into the case. Pry these away
> from the connector bulkhead, and pull the whole thing out of the case.
>
> Pics of the unit are here:
>
> http://www.kenneke.com/vwfi
>
> I am going to be having some exciting news about all this FI stuff soon.
> Stay tuned!
>
> Jon
>
>
>